Jurassic Reef Ecosystems

Digital informal reprint of Leinfelder, R.R. (2001): Jurassic Reef Ecosystems.- In: Stanley, G.D.Jr. (ed.), The History and Sedimentology of Ancient Reef Systems, pp. 251-309, Kluwer Academic/Plenum Publishers, New York. please see remarks for use and other comments on last page. ___________________________________________________________________________________ Chapter 8

Jurassic Reef Ecosystems REINHOLD R. LEINFELDER

1. Introduction 2. Jurassic Reefs 2.1. Distribution of Jurassic Reefs 2.2. General Types of Jurassic Reefs 2.3. Abilities and Demands of Jurassic Reef Organisms: The Key to Paleoenvironmental Reconstruction 2.4. Controlling Factors of Jurassic Reef Ecosystems: The Comparative Approach 3. Intrajurassic Reef Development: Faunistic Evolution or Environmental Change? 3.1. Evolutionary Aspects of Reef Organisms 3.2. Sea-Level Development 3.3. Tectonic Control 4. Conclusions References

251 252 252 253 259 279 293 293 297 297 299 302

1. I ntrodu ction C o r a l s a n d sp o n g e s f r o m Ju r a s s i c r e e f s h a v e a t t r a c t e d b o t h a m a t e u r a n d p r o f e s s i o n a l pa l eo n t o l o g i s t s fo r a lo n g ti m e . In pa r t i c u l a r , th e of t en be a u t i f u l l y p r e s e r v e d c o r a l s , w h i c h m a y l o o k j u s t l i k e a c o r a l sk e l e t o n f r o m a n e xt a n t c o r a l , n o u r i s h e d t h e i d e a t h a t Ju r a s s i c r e e f s w e r e q u i t e si m i l a r t o m o d e r n r e p r e s e n t a t i v e s . A l s o , Ju r a s s i c r e e f s o f t e n a r e c o n s i d e r e d t o h a v e b e e n v e r y p r o l i f i c , h a v i n g o u t c o m p e t e d ev e n t h e m o d e r n G r e a t Ba r r i e r Re e f b y f o r m i n g a r e e f be l t at l e a s t 70 0 0 - k m l o n g . T h i s vi e w pe r s i s t e d no t on l y am o n g am a t e u r pa l e o n t o l o g i s t s bu t al s o a m o n g m a n y g e o s c i e n t i s t s . Ma n y Ju r a s s i c r e e f s c o n t a i n a w e a l t h o f s p o n g e s a n d th e r e f o r e we r e la b e l e d in m a j o r r e v i s i o n s of P h a n e r o z o i c r e e f s y s t e m s a s , , c o r a l ó s p o n g e ì r e e f s , a t l e a s t u n t i l t h e l a s t d e c a d e ( e . g . , Ja m e s , 1 9 8 3 ; F a g e r -

REINHOLD R. LEINFELDER • Institute for Palaeontology and Historical Geology, University of M¸nchen, D-80333 M¸nchen, Germany. The History and Sedimentology of Ancient Reef Systems, edited by George D. Stanley Jr., Kluwer Academic/Plenum Publishers, New York, 2001.

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Ch a p te r 8

s t r o m , 19 8 7 ; S c o t t , 19 8 8 ) . Ho w e v e r , t h i s wa s no t ge n e r a l l y co n s i d e r e d a m a j o r d i f f e r e n c e f r o m m o d e r n r e e f e c o s y s t e m s , b e c a u s e sp o n g e s a l s o m a y p l a y p r o m i n e n t r o l e s i n r e e f s t o d a y , su c h a s Ca r i b b e a n r e e f s . T h e c o m m o n i m p l i c a t i o n w a s t h a t Ju r a s s i c r e e f e c o s y s t e m s w e r e f a i r l y si m i l a r t o m o d e r n r e e f sy s t e m s i n t e r m s o f c o m p o s i t i o n , st r u c t u r e s , a n d e c o l o g i c a l r e q u i r e m e n t s . S o m e e a r l i e r st u d i e s ( e . g . , Cr e v e l l o a n d H a r r i s , 1 9 8 4 ) a n d p a r t i c u l a r l y r e c e n t c o m p a r a t i v e a n a l y s i s o f Ju r a s s i c , c h i e f l y U p p e r Ju r a s s i c r e e f sy s t e m s ( e . g . , Ge i s t e r an d L a t h u i l i Ë r e , 19 9 1 ; L e i n f e l d e r , 19 9 3 a , 19 9 4 b ; No s e , 19 9 5 ; S c h m i d , 19 9 6 ; L e i n f e l d e r e t al . , 1 9 9 6 ; I n s a l a c o e t a l . , 1 9 9 7 ; M a t y s z k i e w i c z , 1 9 9 7 ) h a v e sh o w n t h a t t h e r e e f s c o m p r i s e a w i d e v a r i e t y o f d i f f e r e n t t y p e s a n d t h a t co m p a n i s o n wi t h m o d e r n r e e f s m u s t oc c u r wi t h gr e a t ca u t i o n .

2.

J u r a s s i c Re e f s

T h i s c h a p t e r i l l u s t r a t e s Ju r a s s i c r e e f e c o s y s t e m s b y f o c u s i n g o n si m i l a r i t i e s a n d d i f f e r e n c e s o f r e e f f a u n a , r e e f st r u c t u r e , a n d e c o l o g i c a l d e m a n d s b e t w e e n m o d e r n r e e f s a n d Ju r a s s i c r e e f s . T h i s c o n t r i b u t i o n i s b a s e d o n a n a l y s e s o f r e e f s f r o m t h e l a t e e p o c h o f t h e Ju r a s s i c p e r i o d , b e c a u s e i t w a s a t t h a t t i m e t h a t r e e f s de v e l o p e d m o s t vi g o r o u s l y , an d c o m p a r a t i v e s t u d i e s ca n b e p e r f o r m e d be s t us i n g th i s ti m e in t e r v a l . Ho w e v e r , th e t e m p o r a l de v e l o p m e n t o f r e e f g r o w t h i n t h e c o u r s e o f t h e Ju r a s s i c p e r i o d a l s o w i l l b e b r i e f l y discuss ed. 2 . 1 . D i s t r i b u t i o n of Ju r a s s i c Re e f s I n t e r m s o f t h e g e n e r a l t e c t o n i c se t t i n g , U p p e r Ju r a s s i c c o r a l r e e f s o c c u r r e d pr e d o m i n a n t l y i n va r i a b l e po s i t i o n s on pu r e ca r b o n a t e t o m ix e d c a r b o n a t e ó si l i c i c l a s t i c , f l a t , o r st e e p e n e d r a m p s . Q u i t e a f e w o f t h e m g r e w v e r y c l o s e t o t h e s h o r e l i n e , w h e r e a s o t h e r s w e r e si t u a t e d i n f a i r l y d e e p s e t t i n g s , p o s s i b l y d o w n t o se v e r a l h u n d r e d s o f m e t e r s . E x a m p l e s of co r a l r e e f s on f l a t , pa r t l y ne a r l e v e l - b o t t o m r a m p s ar e w i d e s p r e a d i n E u r o p e ( e . g . , Ge r m a n y , F r a n c e , S p a i n , P o r t u g a l , E n g l a nd : e. g . , A h , 1 9 8 3 ; Au r e l l an d Ba d e n a s , 1 9 9 7 ; Be r t l i n g , 1 9 9 3 ; E r r e n s t , 1 9 9 0 a , b ; F e z e r , 1 9 8 8 ; F l ¸ g e l e t a l . , 1 9 9 3 ; G e i s t e r an d L a t h u i l i Ë r e , 19 9 1 ; I n s a l a c o e t a l . , 1 9 9 7 ; L e i n f e l d e r , 1 9 9 3 a ; L e i n f e l d e r e t a l . , 1 9 9 6 ; N o s e , 1 9 9 5 ) . Co r a l r e e f s at t h e m a r g i n s o f a n d b e h i n d st e e p e n e d r a m p s o c c u r , f o r e x a m p l e , i n S w i t z e n l a n d ( G y g i a n d Pe r s o z , 1 9 8 6 ; P¸ m p i n , 19 6 5 ; Pi t t e t e t a l . , 1 9 9 5 ; T a k a c s , in pn e p . ) a n d i n c e n t r a l a n d so u t h e r n P o r t u g a l ( E l l i s e t a l . , 1 9 9 0 ; L e i n f e l d e r , 1 9 9 4 b , N o s e , 1 9 9 5 ; S c h m i d a n d Jo n i s c h k e i t , 1 9 9 5 ) . C o r a l r e e f s a l s o m a y r i m p l a t f o r m s wi t h de p o s i t i o n a l or by p a s s m a r g i n s , wi t h ex a m p l e s co m i n g f r o m c e n t r a l P o r t u g a l ( L e i n f e l d e r , 1 9 9 2 , 19 9 4 b ) , Au s t r i a ( S t e i g e r , 19 8 1 ; S t e i g e r an d W u r m , 1 9 8 0 ) , I t a l y ( S a r t o n i o , 1 9 8 9 ) , t h e Ca u c a s u s ( S c o t t , 1 9 8 8 ) , Mo n o c c o ( S t e i g e n a n d Ja n s a , 1 9 8 4 ) , a n d t h e U S G u l f Co a s t ( B a r i a e t a l . , 1 9 8 2 ; M o n t g o m e r y , 19 9 3 , 1 9 9 6 ) , am o n g m a n y ot h e r l o c a l i t i e s . Sp o n g e re e f s a l s o we r e wi d e s p r e a d , wi t h pr o m i n e n t oc c u r r e n c e s in Ro m a n i a ( D r a g a n e s c u , 1 9 7 6 ; H e r r m a n n , 1 9 9 6 ) , P o l a n d ( T r a m m e r , 1 9 8 8 ; Ma t ys -

Ju ra ssi c Re e f Ec o sy ste m s

253

z k i e w i c z , 1 9 9 6 ) , s o u t h e r n G e r m a n y ( G w i n n e r , 1 9 7 6 ; W a g e n p l a s t , 1 9 7 2 ; Me y e r a n d S c h m i d t - K a l e r , 1 9 8 9 ; Br a c h e r t , 1 9 9 2 ; L e i n f e l d e r e t a l . , 1 9 9 4 , 1 9 9 6 ; M a t y s z k i e w i c z , 19 9 7 ; We r n e r e t al . , 1 9 9 4 ; K e u p p e t al . , 1 9 9 6 ; P i s e r a , 19 9 7 ) , S w i t z e r l a n d ( T a k a c s , i n pr e p . ) , F r a n c e ( G a i l l a r d , 19 8 3 ; P a l m e r an d F ¸ r s i c h , 1 9 8 1 ) , S p a i n ( D e u s c h e t al . , 1 9 9 1 ; K r a u t t e r , 19 9 5 , 19 9 6 ) , bu t al s o de v e l o p e d i n Po r t u g a l ( R a m a l h o , 19 8 8 ; L e i n f e l d e r e t al . , 1 9 9 3 a ) , I t a l y ( K r a u t t e r , 19 9 6 ) , a n d Mo r o c c o ( W i e d e n m a y e r , 1 9 8 0 ; W a r m e e t a L , 1 9 8 8 ) , a m o n g m a n y o t h e r p l a c e s . Mi c r o b o l i t e r e e f s a r e p a r t i c u l a r l y c o m m o n i n I b e r i a , P o r t u g a l ( L e i n f e l d e r e t al . , 1 9 9 3 b ; S c h m i d , 19 9 5 ) , an d of f s h o r e No v a S c o t i a ( J a n s a e t a l . , 1 9 8 9 ) . F o r a m o r e c o m p l e t e l i s t o f r e f e r e n c e s o n o c c u r r e n c e s o f Ju r a s s i c c o r a l , s p o n g e , a n d m i c r o b o l i t e r e e f s , s e e L e i n f e l d e r ( 1 9 9 4 a ) . I m p o r ta n t o c c u r r e n c e s ar e al s o i n d i c a t e d i n F i g . 1 . F o c u s i n g o n t h e p l a t e t e c t o n i c se t t i n g o f t h e Ju r a s s i c m o s t r e e f s g r e w o n t h e st a b l e a n d w i d e sh e l f o f t h e n o r t h e r n T e t h y s m a r g i n . P a r t i c u l a r l y d u r i n g t h e L a t e Ju r a s s i c , se a l e v e l w a s a b o u t 1 0 0 t o 1 5 0 m h i g l i e r t h a n t o d a y ( H a q e t a l . , 1 9 8 8 ) , wh i c h i n E u r o p e r e s u l t e d i n m a n y pe r i c o n t i n e n t a l an d ep i c o n t in e n t a l sh a l l o w t o m o d e r a t e l y d e e p sh e l f se a s c o n n e c t i n g t h e T e t h y s . I n a b e l t e x t e n d i n g f r o m Ru s s i a t o Ru m a n i a t h r o u g h P o l a n d , G e r m a n y , S w i t z e r l a nd , E a s t e r n F r a n c e , ea s t e r n S p a i n , S o u t h e r n P o r t u g a l t o T e x a s an d Ne w M e x i c o , r e e f s d e v e l o p e d ex t e n s i v e l y , es p e c i a l l y du r i n g t h e Ox f o r d i a n . Ho w e v e r , no c o n t i n u o u s ba r r i e r r e e f de v e l o p e d ; i n s t e a d , r e e f s oc c u r r e d as i s o l a t e d bo d i e s o f v a r i a b l e e x t e n t i n a b e l t l i k e y e t b r o a d sh e l f a r e a . A n o t h e r se a w a y w i t h r e e f d e v e l o p m e n t w a s t h e N o r t h A t l a n t i c r i f t sy s t e m s a n d a d j a c e n t e p i c o n t i n e n t a l s e a s , w h i c h d u r i n g t h e L a t e Ju r a s s i c c o n n e c t e d t h e T e x a s r e a l m w i t h t h e P o r t u g u e s e L u s i t a n i a n r i f t ba s i n , we s t e r n F r a n c e , E n g l a n d , an d No r t he r n G e r m a n y . Ma n y se a w a y s c o n n e c t e d t h e e p i c o n t i n e n t a l se a s a d j a c e n t t o t h e n o r t h e r n T e t h y s w i t h t h o s e a d j a c e n t t o t h e N o r t h A t l a n t i c r i f t sy s t e m . Re e f s w e r e l e s s w i d e s p r e a d , y e t e x i s t i n g o n t h e s o u t h e r n T e t h y s sh e l f ( s e e S e c t i o n 3 ) . D u r i n g t h e L a t e Ju r a s s i c , w a r m - w a t e r c o r a l r e e f s a n d c o r a l a s s o c i a t i o n s a l s o g r e w i n f a i r l y l o w ( c o r r e c t i o n : h i g h ) l a t i t u d e s , su c h a s i n n o r t h e r n E n g l a n d ( A l i , 1 9 8 3 ; I n s a l a c o e t a l . , 1 9 9 7 ) a n d so u t h e r n A r g e n t i n a ( L e g g a r e t a , 1 9 9 1 ) . T h i s i s e v i d e n c e o f v e r y e q u i l i b r a t e d se a w a t e r t e m p e r a t u r e s ( L e i n f e l d e r , 19 9 4 a ) .

2.2.

G e n e r a l Ty p e s o f J u r a s s i c R e e f s

J u r a s s i c r e e f s c o n t a i n v a r i o u s p r o p o r t i o n s o f , , p a r a z o a n s ì ( s p o n g e s) a n d / o r , , t r u e ì m e t a z o a n r e e f bu i l d i n g or g a n i s m s ( c o r a l s an d ot h e r s ) , m i c r o b i a l cr u s t s , m u d , an d pe l o i d a l t o ca l c i c l a s t i c pa r t i c l e s , as we l l as hi g h l y va r i a b l e pr o p o r t i o n s o f f r a m e w o r k d e v e l o p m e n t o r p r e s e r v a t i o n . T h e b a s i c t y p e s o f J ur a s s i c r e e f s c a n be gr o u p e d i n t o t h e f o l l o w i n g ca t e g o r i e s , al t h o u g h a gr e a t va r i e t y of t r a n s i t i o n a l a n d su c c e s s i o n a l t y p e s e x i s t ( F i g . 2 ) :

• • •

C o r a l r e e f ty p e s S i l i c e o u s sp o n g e r e e f t y p e s Pure microbolite reef types

coral reefs coral reef & sponge reef belt major occurrences of pure microbolites

FIGURE 1. The global distribution of coral, siliceous sponge and pure microbolite reefs during die Late Jurassic. (Modified after Leinfelder, 1994a.) Pangea paleogeography after Scotese et al. (1993). Reefs are more frequent along the northern Tethys shelf. Note occurrence of warm-water coral reefs in high paleolatitudes, indicating equilibrated water temperatures. Reefs were less frequent during die Early and Mid-Jurassic (see sketch maps in Leinfelder, 1994a).

(Note Figure is originally in landscape format, it was turned here 90° for better readability of this online-copy)

FIGURE 2. Compositional types of Jurassic reefs. The end-members coral reefs, siliceous sponge reefs, microbolite reefs, mudmounds, and bioclastic sand shoals form .many transitional types. Most common types are indicated by dots. (After Leinfelder, 1993a, and Leinfelder and Keupp, 1995, modified.)

2.2.1. Coral Reefs R e c e n t l i t e r a t u r e o n U p p e r Ju r a s s i c c o r a l r e e f t y p e s e x i s t s ( e . g . , L e i n f e l d e r , 1 99 3 a, 19 9 4a , b; Le i nf e ld e r e t al. , 1 99 6 ; Nos e , 199 5 ; Ins a la c o 199 6 a, b ; In s a l a c o e t a l . , 1 9 9 7 ) , t h e r e f o r e o n l y a sh o r t r e v i e w o f c o r a l r e e f t y p e s i s g i v e n h e r e i n t a b u l a r f o r m ( F i g . 3 ) . T h e d o m i n a n t f a u n a o f t h e s e r e e f s a r e sc l e r a c t i n i a n c o r a l s t h a t m a y o r m a y n o t b e p r e s e r v e d i n l i f e p o s i t i o n . I f p r e s e r v e d i n si t u , i n r a r e c a s e s t h e y m a y bu i l d t r u e f r a m e s t o n e s wi t h m a s s i v e co r a l s gr o w i n g o n t o p of e a c h o t h e r . C o r a l b u s h e s f o r m i n g b a f f i e s t o n e s , h o w e v e r , a r e m o r e f r eq u e n t a n d i n r a r e ex a m p l e s m a y gr o w up t o 4 m . I n ge n e r a l , di m e n s i o n s ar e f r o m a f e w

Chapter 8

Small patches of massive corals with indistinct, irregular outline, embedded within coarse bioclastic debris. Bioeroders frequent, binding organisms rare to lacking. Massive, nodular coral colonies prevailing. Low to medium diversity coral fauna. important genera are Actlnastrea, Psammogyra, Amphiastrea, Convexastrea and Pseudocoenia. Low-diversity types dominated by Actlnastrea. Framestone patches metre-sized and smaller, coral debris. facies may however amount to thickness of tens of metres

Similar to above, but microbolite crusts and other microencrusters frequent. High-diversity coral fauna. Stacked reeefs up to150 metres thick.

Steepiy bordered, distinct biohems ot several metres height. Medium to high-diversity coral fauna. Phaceloid corals (Calamophylliopsis) and ramose corals are very important, particularly during initial stages of growth. May contain clayey matrix. Microbial crusts abundant, offen forming framework. Reef caves frequent, partly occupied by downwards facing microboilte hemispheroids and cave fauna. Reefs may be stacked, partially interbedded with pure microboilte reefs.

Medium to high-diversity coral fauna, composed largely of foliose and patellate corais. Microsolena, Thamnasterla, Fungiastrea a n d Trocharea particulary frequent. Diametres of platy corals up to 1 metre. May contain abundant dish-shaped lithistid sponges, occasionally grading into mixed coral-siliceous sponge biostromes. Individual biostromes are metre-thick but may be amalgamated.

Low-diversity coral fauna, either with broad, dish- to tunnel like, irregular coral morphologies, or with a dominance ot phaceloid (Calamophylliopsis ), ramose ( Ovalastrea) corals as well as sediment-sticking variabilities of morphovariable corals (Microsolena, Thamnasteria, Convexastrea). No microbial crusts. Individual biostromes may attain heights of several metres.

FIGURE 3. The most prominent reef types of the Late Jurassic (Simplified after Nose and Leinfelder, submitted for publication).

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Jurassic Reef Ecosystems

SILICEOUS SPONGE MICROBOLITE MUDMOUNDS Mounds wlth dlstinct, partly steep outlines, metre to tens of metres high; often composite structures. Composed of highdlversity liithistid and/or hexactinellid sponge fauna, microbolite crusts and calcareous mud, partly peloidal or intraclastic. Additional organisms. such as encrusters , bivalves, brachiopods, belemnites and ammonites frequent.

Mostly dominated by small, tube and vase shaped hexactinosan sponges, forming decimeter-thick levels. Occasionally also dominance of dish-shaped sponges. No microbial crusts.

Typically of very low-diversity, dominated by dish-shaped hexactinosan sponges in rock-forming quantities. Microbial crusts regularly occurring but thin. Individual meadows cm-thick, stacked to several metre thick biostromes. Ammonites abundant. Additional fauna very impoverished. Occasionally higher diversity biostromes, with more microbial crusts and a muddy, peloidal matrix. Additional fauna diversified.

Steep-walled structures, sometimes with overhangs, from decimetre size up to 30 metres thick. Microbial crusts in rockforming quantities. Microencrusters, such as Terebella and Tubiphytes may be frequent, arranged in distinct zones. Siliceous sponges may occur but generally are limited to distinct levels. Framboidal pyrite end authigenic giauconite frequent. Dysaerobic bivalves (Aulacomyella) and Chondrites may be abundant between reefs. Occasionally interbedded with metazoan-microbolite reefs.

FIGURE 3. Continued.

d e c i m e t e r s h e i g h t u p t o st a c k e d r e e f s a t t a i n i n g t h e c u m u l a t i v e t h i c k n e s s o f 1 0 0 m a n d m o r e . Mo s t f r e q u e n t a r e c o r a l r e e f s w i t h t h i c k n e s s r a n g i n g f r o m se v e r a l m e t e r s u p t o 1 5 m . U p p e r Ju r a s s i c c o r a l r e e f s c a n b e t y p i f i e d b y t h e i r f a u n a l c o m p o s i t i o n , d o m i n a n c e , a n d f r e q u e n c y o f c o r a l sp e c i e s , t h e i r s e d i m e n t o l o g i c a l c h a r a c t e r i s t i c s , a n d t h e i r g e n e r a l sh a p e a n d d i m e n s i o n s . I n g e n e r a l , m e d i u m - t o h i g h - d i v e r s i t y c o r a l r e e f s w i t h 4 0 a n d m o r e c o r a l sp e c i e s i n o n e c o r a l a s s o c i a t i o n sh o u l d b e d i s t i n g u i s h e d f r o m l o w - d i v e r s i t y c o r a l r e e f s . [ T u r n s e k e t a l . ( 1 9 8 1 ) , r e c o r d e d 1 0 9 sp e c i e s o f c o r a l s , h y d r o z o a n s , a n d

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c h a e t e t i d s i n a ba r r i e r - t y p e r e e f co m p l e x o f S l o v e n i a , bu t t h i s ap p e a r s t o be a b u l k n u m b e r f r o m a l l r e e f b o d i e s . ] Me d i u m - t o h i g h - d i v e r s i t y c o r a l r e e f s c o m p r i s e co r a l ó d e b r i s pi l e r e e f s , co r a ló m i c r o b o l i t e ó d e b r i s pi l e r e e f s , m a r l y c o r a l ó m i c r o b o l i t e r e e f s , co r a l m u d m o u n d s , a n d co r a l ó m i c r o b o l i t e bi o h e r m s , a n d b i o s t r o m e s . L o w - d i v e r s i t y c o r a l r e e f s e n c o m p a s s l o w - d i v e r s i t y co r a l ó d e b r i s pi l e r e e f s , A m p h i a s t r e a p a t c h r e e f s , va r i o u s t y p e s of m a r l y co r a l m e a d o w s , an d co r a l ó s t r o m a t o p o r o i d m u d m o u n d s ( F i g . 3) . 2 . 2 . 2 . S i l i c e o u s S p o n g e Re e f s T h e s e r e e f s ar e ei t h e r of bi o s t r o m e t y p e or ex h i b i t a m u d m o u n d ch a r a c t e r d u e t o t h e l a r g e c o n t r i b u t i o n o f f i n e - g r a i n e d c a r b o n a t e , p a r t o f w h i ch c o r r e s p o n d s t o m i c r o b i a l c r u s t s . S i l i c e o u s sp o n g e s a r e c o m p o s e d o f v a r i o u s p r o p o r t i o n s o f h e x a c t i n e l l i d sp o n g e s a n d , , l i t h i s t i d ì d e m o s p o n g e s . S i l i c e o u s s p o n g e s ar e t h e m o s t ch a r a c t e r i s t i c el e m e n t of t h e s e r e e f s , bu t of t e n do no t d o m i n a t e vo l u m e t r i c a l l y ov e r m i c r o b i a l cr u s t s an d ca l c a r e o u s m u d . M u d m o u n d s m a y b e f r o m a f e w d e c i m e t e r s u p t o se v e r a l t e n s o f m e t e r s h i g h . T h e l a r g e r m o u n d s a r e o f t e n c o m p o s e d o f st a c k e d , sm a l l e r m o u n d s ( s e e S e c t i o n 2 . 4 . 4 ) . S i l i c e o u s sp o n g e ó m i c r o b o l i t e m u d m o u n d s a r e n o r m a l l y o f m e d i u m t o h i g h d i v e r s i t y i n t e r m s o f sp o n g e t a x a , a l t h o u g h a g r e a t d e a l o f w o r k i s st i l l t o b e d o n e t o d e t e r m i n e sp o n g e a s s o c i a t i o n s i n a q u a n t i t a t i v e w a y a t t h e sp e c i e s l e v e l . Be s i d e s t h e v a r i o u s t y p e s o f sp o n g e m u d m o u n d s , t h e r e a r e a l o t o f sp o n g e b i o s t r o m e s , w h i c h i n t h e c a s e o f t h e O x f o r d i a n sp o n g e b e d s f r o m e a s t e r n S p a i n st r e t c h a c r o s s m o r e t h a n 7 0 , 0 0 0 k m 2 , w i t h t h e i r o r i g i n a l e x t e n s i o n ce r t a i n l y ha v i n g be e n m u c h br o a d e r ( K r a u t t e r , 19 9 5 ) . S p o n ge b i o s t r o m e s o r sp o n g e m e a d o w s a r e v a r i a b l e a n d m o s t l y o f l o w f a u n a l d i v e r s i t y . Ma r l y m e a d o w s d o m i n a t e d b y v a s e - a n d t u b e - s h a p e d sp o n g e s a r e d i s t i n g u i s h e d f r o m c a l c a r e o u s b i o s t r o m e s d o m i n a t e d b y d i s h - s h a p e d sp o n g e s . A b u n d a n c e o f s p o n g e s m a y b e v e r y h i g h , w i t h s p o n g e s b e i n g a l m o s t t h e on l y r o c k e l e m e n t , su c h a s i n t h e c a s e o f t h e S p a n i s h sp o n g e b i o s t r o m e s ( s e e S e c t i o n 2. 4 . 4 ) . So m e w h a t mu d d i e r , th i c k - b e d d e d bi o s t r o m e s ha v e le s s f r e q u e n t sp o n g e s b u t c o n t a i n a l o t o f m i c r o b i a l c r u s t s ( F i g . 3 ) 2 . 2 . 3 . P u r e Mi c r o b o l i t e Re e f s A n i n t e r e s t i n g r e e f t y p e i s t h e o n e t h a t i s a l m o s t c o m p l e t e l y c o m p o s ed o f m i c r o b o l i t e . S u c h r e e f s w e r e w i d e s p r e a d i n so m e a r e a s d u r i n g t h e L a t e J u r a s s i c a n d a r e a l s o k n o w n f r o m t h e E a r l y J u r a s s i c . M i c r o b o l i t e c r u st s , d o m i n a t e d b y c l o t t e d , t h r o m b o l i t i c f a b r i c , f o r m a d e n s e f r a m e w o r k , bu i l d i n g u p bi o h e r m s f r o m a f e w de c i m e t e r s up to 30 m in he i g h t ( L e i n f e l d e r e t a l . , 1 9 9 3 a , b ) . Ma c r o f a u n a i s e i t h e r v i r t u a l l y a b s e n t , c o n f i n e d t o n a r r o w l e v e l s , o r i n r a r e c a s e s sc a r c e l y sc a t t e r e d i r r e g u l a r l y t h r o u g h o u t t h e r e e f s i n m i n i a t u r e f o r m s . W h e n e v e r f a u n a a p p e a r s , i t i s m o s t l y si l i c e o u s s p o n g e s , c h i e f l y o f t h e h e x a c t i n e l l i d t y p e . S e r p u l i d s , t e r e b e l l i d w o r m s , an d en i g m a t i c en c r u s t i n g m i c r o o r g a n i s m s m a y b e o c c a s i o n a l l y v e r y f r e q u e n t . A n i n t e r e s t i n g f e at u r e i s t h a t su c h p u r e m i c r o b o l i t e r e e f s a l s o m a y o c c u r i n a r e p e t i t i v e , st a c k e d m a n n e r w i t h i n so m e c o r a l r e e f s ( s e e S e c t i o n 2 . 4 . 4 ) .

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2 . 3 . A b i l i t i e s an d De m a n d s of Ju r a s s i c Re e f Or g a n i s m s : T h e Ke y to P a l e o e n v i r o n m e n t a l R e c o n s t r u c t i o n R e e f o r g a n i s m s a r e st r o n g l y d e p e n d e n t o n e a c h o t h e r , a n d t h u s p l a y m a n y d i f f e r e n t r o l e s i n r e e f sy s t e m s , w h i c h a r e o f t e n r e f e r r e d t o a s , , c i t i e s u n d e r w a t e r ì d u e t o t h e f o r m a t i o n o f p r e s e r v a b l e st r u c t u r e s a n d t h e i n t e n s e i n t e r d e p e n d e n c e o f t h e r e e f b i o t a . I n su c h c o m p a r i s o n s , t h e r e e f o r g a n i s m s a r e d e s c r i b e d a s b e l o n g i n g t o d i f f e r e n t g u i l d s , t h u s h a v i n g d i f f e r e n t , , j o b s , ì su c h a s ch i e f co n s t r u c t o r s , ce m e n t e r s , r e c y c l e r s of bu i l d i n g m a t e r i a l , g a r d e n e r s , s h o p k e e p e r s , wa t e r f i l t e r e r s , w a s t e r e c y c l e r s , an d m u c h m o r e ( e . g . , F a g e r s t r o m , 19 8 7 , G i n s b u r g , 19 9 7 ; L e i n f e l d e r an d Gi n s b u r g , 19 9 8 ) . A l l j o b s a r e n e c e s s a r y t o k e e p t h e r e e f c i t y sy s t e m r u n n i n g a n d n o si n g l e c h a i n o r w e b l i n k c a n b e m i s s i n g . I n o r d e r t o a c c o m p l i s h t h e i r t a s k s , r e e f o r g a n i sm s h a v e v e r y sp e c i a l d e m a n d s a n d a b i l i t i e s . I n t h e f o s s i l e x a m p l e , i t i s a b s o l u t e l y n e c e s s a r y t o u n c o v e r t h o s e a b i l i t i e s a n d d e m a n d s o f e x t i n c t r e e f o r g an i s m s i n o r d e r t o e v a l u a t e t h e i r r o l e a n d e f f i c i e n c y i n t h e f o s s i l r e e f s y s t e m. O n l y b y d o i n g s o i s i t po s s i b l e t o r e c o n s t r u c t t h e f a c t o r s co n t r o l l i n g t h e gr o w t h of f o s s i l r e e f s . T h i s i s t h e u l t i m a t e g o a l i n a n a l y s i s o f f o s s i l r e e f s a nd a l l o w s u s i n g f o s s i l r e e f s as pa l e o e n v i r o n m e n t a l an d pa l e o s t r u c t u r a l m o n i t o r s ( L e i n f e l d e r , 1 9 9 4 a ; se e a l s o S e c t i o n 2 . 4 ) . 2 . 3 . 1 . T h e M a s t e r Bu i l d e r s : R e e f C o r a l s T h e m a j o r c o n s t r u c t o r s o f m o d e r n r e e f s a r e t h e sc l e r a c t i n i a n c o r a l s , w h i c h d e p e n d i n g o n t a x a h a v e v a r i a b l e g r o w t h r a t e s , sh a p e s , a n d f r a g i l i t y . T h e p a r a m o u n t f e a t u r e o f t h e gr e a t m a j o r i t y of m o d e r n r e e f co r a l s i s t h e i r pe r f e c t s y m b i o t i c r e l a t i o n s h i p wi t h zo o x a n t h e l l a t e . c o r a l s , m a k i n g t h e m l a r g e l y i n d e p e n d e n t o f t h e h e t e r o t r o p h i c f e e d i n g m o d e . Be s i d e s t h e t r o p i c a l r e e f c o r a l s , t h e r e a r e n o n z o o x a n t h e l l a t e sp e c i e s , so m e o f w h i c h f o r m r e e f l i k e ( t h o u g h no r m a l l y no t pr e s e r v a b l e ) m e a d o w s i n de e p an d c o l d wa t e r s ( H e n r i c h e t al . , 1 9 9 6 ) . J u r a s s i c sc l e r a c t i n i a n s h a d a h i g h a n d a c r o s s t h e e p o c h s o f t h e Ju r a s s i c g e n e r a l l y in c r e a s i n g ta x o n o m i c di v e r s i t y ( s e e S e c t i o n 3 ) . Du r i n g th e L a t e J u r a s s i c , c o r a l a s s o c i a t i o n s g e n e r a l l y a p p e a r e d i n l a r g e - s c a l e , sh a l l o w i n g u p w a r d su c c e s s i o n s i n a b r o a d v a r i e t y o f e n v i r o n m e n t s w h o s e g e n e r a l e n v i r o n m e n t a l pa r a m e t e r s i n m a n y ca s e s ca n be de t e r m i n e d by cr i t e r i a i n d e p e n d e n t of co r a l s . T h i s en a b l e s pa l e o n t o l o g i s t s t o ev a l u a t e t h e ab i l i t i e s a n d d e m a n d s o f Ju r a s s i c c o r a l s . O n c e c a l i b r a t e d , c o r a l a s s o c i a t i o n s t h e n c a n b e u s e d a s e n v i r o n m e n t a l m o n i t o r s f o r se t t i n g s t h a t c a n n o t b e r e c o n s t r u c t e d b y o t h e r c r i t e r i a . I n t h i s c h a p t e r 1 w a n t t o p a r t i c u l a r l y e m p h a s i z e si m i l a r i t i e s a n d d i f f e r e n c e s o f Ju r a s s i c c o r a l s f r o m m o d e r n c o r a l s . 2 . 3 . l a . B a t h y m e t r y a n d t h e P h o t o s y m b i o s i s Q u e s t i o n . On e o f t h e k e y q u e s t i o n s i s w h e t h e r Ju r a s s i c r e e f c o r a l s a l r e a d y p o s s e s s e d a p h o t o sy m b i o t i c r e l a t i o n s h i p wi t h a l g a e , wh i c h i n m o d e r n r e e f co r a l s i s pa r a m o u n t i n de t e r m i n i n g t h e en v i r o n m e n t a l ne c e s s i t i e s an d ph y s i o l o g i c a l ab i l i t i e s of co r a l s an d

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i n p a r t i c u l a r a l l o w s t h e m t o g r o w f a s t . D e s p i t e d i a g e n e t i c a l t e r a t i o n Ju r a s s i c c o r a l s d o o f t e n sh o w a d i s t i n c t m a c r o s c o p i c b a n d i n g o f t h e i r sk e l e t o n s . M i c r o s t r u c t u r e s o f t h e i n d i v i d u a l b a n d s a r e a s t o n i s h i n g l y si m i l a r t o m o d e r n z o o x a n t h e l l a t e c o r a l s , sh o w i n g l o w - a n d h i g h - d e n s i t y b a n d s , w h i c h i n m o d e r n c o r a l s a r e a t t r i b u t e d t o se a s o n a l d i f f e r e n c e s i n i l l u m i n a t i o n . H i g h e r i l l u m i n a t i o n al l o w s f o r a m o r e r a p i d l i n e a r gr o w t h , as i t i s r e f l e c t e d as a ba n d o f l o w e r st r u c t u r a l d e n s i t y ( A l l i s o n e t a l . , 1 9 9 6 ) . T h e d i s t i n c t d e v e l o p m e n t o f h i g h a n d l o w - d e n s i t y b a n d i n g i n m a n y U p p e r Ju r a s s i c c o r a l s su p p o r t s a g o o d a r g u m e n t ov e r wh e t h e r m a n y of t h e m al r e a d y po s s e s s e d zo o x a n t h e l l a e o r ot h e r algal symbionts. T h e f o l l o w i n g a d d i t i o n a l a r g u m e n t s su p p o r t su c h i n t e r p r e t a t i o n : ( 1 ) M a n y J u r a s s i c t a x a ar e h i g h l y i n t e g r a t e d f o r m s , wh i c h m e a n s t h a t t h e y de v e l o p e d c o m p l e x c a l i c a l f e a t u r e s , su c h a s t h a m n a s t e r i o i d a n d m e a n d r o i d t y p e s w i t h p e r f o r a t e se p t a e , d i s s e p i m e n t s , a n d p e n n u l a e ( N o s e , 1 9 9 5 ) . S u c h f o r m s a r e e x c l u s i v e l y z o o x a n t h e l l a t e t o d a y ( C o a t e s a n d Ja c k s o n , 1 9 8 7 ) , w h e r e a s si m p l e r f o r m s m a y be bo t h z o o x a n t h e l l a t e an d no n z o o x a n t h e l l a t e . ( 2 ) W i t h i n s h a l l o w i n g - u p w a r d s u c c e s s i o n s , Ju r a s s i c c o r a l a s s o c i a t i o n s a r e r e s t r i c t e d t o t h e u p p e r p a r t . ( 3 ) Ju r a s s i c c o r a l a s s o c i a t i o n s a r e c o m m o n l y a s s o c i a t e d w i t h h i g h - e n e r g y se d i m e n t s su c h a s o o l i t e s o r sh a l l o w l a g o o n a l se d i m e n t s , l i k e d a s y c l a d a c e a n l i m e s t o n e s a n d i n t e r t i d a l l o f e r i t e se q u e n c e s . ( 4 ) J u r a s s i c c o r a l a s s o c i a t i o n s m a y sp a n a l a r g e r b a t h y m e t r i c f r a m e w o r k t h a n m o d e r n r e e f a l c o r a l a s s o c i a t i o n s a n d e v e n sh o w a p a r t i a l o v e r l a p w i t h si l i c e o u s s p o n g e a s s o c i a t i o n s of de e p e r wa t e r s . Ne v e r t h e l e s s , di s t i n c t a s s o c i a t i o n s ch a n g e c h a r a c t e r i s t i c a l l y al o n g t h e ba t h y m e t r i c gr a d i e n t , wi t h de e p e r wa t e r or t u r b i d s e t t i n g s c h a r a c t e r i z e d b y a d o m i n a n c e o f p l a t e - s h a p e d c o r a l s . P l a t e sh a p e i s a w i d e s p r e a d a d a p t a t i o n t o w a r d l o w e r i l l u m i n a t i o n . T h e r e a r e so m e Ju r a s s i c m o r p h o v a r i a b l e c o r a l t a x a t h a t sh o w n o d u l a r g r o w t h i n s h a l l o w w a t e r , f l a t t e n e d , ir r e g u l a r to pl a t e - s h a p e d gr o w t h in lo w - l i g h t se t t i n g s , an d br a n c h i n g g r o w t h f o r m u n d e r e l e v a t e d se d i m e n t i n f l u x ( N o s e , 1 9 9 5 ; N o s e a n d L e i n f e l d e r , 19 9 7 ) . De e p e r - w a t e r as s o c i a t i o n s m i g h t be c o m p l e t e l y co m p o s e d o f p l a t e - s h a p e d t a x a , s u c h a s t h e m a n y m i c r o s o l e n i d a s s o c i a t i o n s f r om I b e r i a o r Fr a n c e ( E r r e n s t , 19 9 0 a , b ; L e i n f e l d e r e t al . , 1 9 9 6 ; I n s a l a c o , 19 9 6 a ) . I n th e t r a n s i t i o n a l z o n e w i t h l i t h i s t i d d e m o s p o n g e s , so m e Ju r a s s i c m i c r o s o l e n i d c o r a l s m a y de v e l o p t h i n pl a t e s h a p e s m e a s u r i n g m o r e t h a n 1 m ac r o s s ( L e i n f e l d e r e t a l . , 1 9 9 3 a ) . H o w e v e r , p l a t y sh a p e s m i g h t a l s o b e a n a d a p t a t i o n t o w a r d po o r pl a n k t o n av a i l a b i l i t y or os m o t i c nu t r i t i o n , an d m o r e o v e r a t w o d i m e n s i o n a l pl a t e - s h a p e d cr o s s - s e c t i o n th r o u g h a co r a l co l o n y ne e d no t n e c e s s a r i l y c o r r e s p o n d t o a si m i l a r t h r e e d i m e n s i o n a l p l a t e sh a p e ( F i g . 4 ) . A d d i t i o n a l l y , b u t n o t u n e q u i v o c a l l y , p a r t i a l su p p o r t f o r t h e o c c u r r e n c e o f p h o t o s y m b i o n t s i n M e s o z o i c r e e f co r a l s co m e s f r o m ca r b o n an d ox y g e n i s o t o p e s . S t a n l e y a n d S w a r t ( 1 9 9 5 ) h a v e ar g u e d t h a t a po s i t i v e co r r e l a t i o n of t h e s e i s o t o p e r a t i o s as we l l as ox y g e n r a t i o s ab o v e ó 6 ∆ O1 8 a r e ch a r a c t e r i s t i c o f n o n z o o x a n t h e l l a t e f o r m s d u e t o n e a r - e q u i l i b r i u m co n d i t i o n s w i t h th e a m b i e n t se a w a t e r . S t r o n g c l u s t e r i n g o f v a l u e s a r o u n d ó 3 t o + 1 ∆ C1 3 a n d ó 5 t o ó 3 ∆ O 1 8 i s i n t e r p r e t e d as t h e r e f l e c t i o n of t h e vi t a l ef f e c t of zo o x a n t h e l l a e .

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FIGURE 4. Three-dimensional reconstruction of microsolenid corals from the Swiss Liesberg Beds (Oxfordian). The irregular funnel to spiral shape may appear dish-shaped in a fragmental, twodimensional cross-section. Growth form is interpreted as ,best-fitë adaptation toward both reduced illumination and background sedimentation. (From Tacaks, unpublished data.)

T h e a u t h o r s u s e d Me s o z o i c c o r a l s t h a t w e r e st i l l p r e s e r v e d a s a r a g o n i t e . H o w e v e r , no t al l t h e s e r e s u l t s ar e co m p a t i b l e wi t h t h e ab o v e cr i t e r i a . Us i n g P o l i s h m a t e r i a l , t h e sp e c i e s T h a m n a s t e r i a c o n c i n n a s h o u l d b e a n o n z o o x a n t h e l l a t e f o r m a c c o r d i n g t o S t a n l e y a n d S w a r t ( 1 9 9 5 ) , w h e r e a s t h i s s p ec i e s a n d i t s cl o s e r e l a t i v e T h a m n a s t e r i a l o b a t a s h o w cl e a r l y de v e l o p e d gr o w t h b a n d i n g , h i g h l y i n t e g r a t e d c a l i c e s , a n d f l a t t e n i n g i n t e r p r e t e d t o b e f r o m g r ea t e r w a t e r d e p t h . I s o t o p i c v a l u e s o f I b e r i a n ( n o n a r a g o n i t i c ) m a t e r i a l sh o w n o i s o t o p e c o r r e l a t i o n an d pl o t i n t h e zo o x a n t h e l l a t e f i e l d wi t h t h e i r ∆ C 1 3 v a l u e s bu t ar e d e p l e t e d i n ox y g e n , wh i c h m i g h t be a di a g e n e t i c ef f e c t ( N o s e an d S c h m i d , u n p u b l i s h e d r e s u l t s ) . T h i s co n t r a d i c t i o n m a y be du e t o t h e f a c t t h a t i n bo t h a r a g o n i t i c an d ne o m o r p h i c m a t e r i a l , di a g e n e t i c ov e r p r i n t i n g co u l d b e to o i n t e n s e t o u s e t h i s m e t h o d o r r a t h e r t h a t t h e i s o t o p e s i g n a l s o f J u r a ss i c c o r a l s w e r e n o t a s st r o n g a s i n m o d e r n c o r a l s b e c a u s e t h e e f f i c i e n c y o f t h e p h o t o s y m b i o t i c r e l a t i o n w a s st i l l m u c h l o w e r t h a n i n m o d e r n c o r a l s ( N o s e a n d L e i n f e l d e r , 19 9 7 ) . T h e r e a r e a c o u p l e o f i m p o r t a n t a r g u m e n t s t h a t su p p o r t t h e l a s t st a t e m e n t . D e s p i t e sh o w i n g t h e d i s t i n c t b i m o d a l g r o w t h b a n d s o f m o d e r n z o o x a n t h e l l a t e s , g r o w t h r a t e s o f Ju r a s s i c c o r a l s w e r e c o n s i d e r a b l y l e s s t h a n t h o s e o f m o d e r n c o r a l s , be i n g i n t h e r a n g e of 3 t o 5 m m / y e a r i n co m p a r i s o n wi t h t h e m o d e r n zooxant hellate cor als' a v e r a g e r a t e s of 10 to 1 5 m m / y e a r ( F i g . 5 ) .

262

Ch a p t e r 8 max. 250

4

16 Upper Jurassic reef corals

14 avg

12 10 8 6 avg 4 2 0

ANNUAL GROWTH RATES (mm / year )

3

2 Upper Jurassic reef corals

18

modern reef corals

20

modern reef corals

5

1

0 L / H - RATIO low density / high density band

FIGURE 5. (Left) Linear growth rates of Upper Jurassic and modern reef-building scleractinians; avg, average. (Recent data after Buddemeier and Kinzie, 1976; Schuhmacher, 1976.) (Right) Ratio of low to high density band thickness in Upper Jurassic and modern reef building scleractinians (recent data after Highsmith, 1979). (Modified after Nose and Leinfelder, 1997.)

M a x i m u m va l u e s of m o d e r n co r a l s ar e 28 0 m m / y e a r an d m o r e , wh e r e a s t h e h i g h e s t g r o w t h r a t e s o f Ju r a s s i c c o r a l s m e a s u r a b l e t o d a t e a r e a b o u t 1 3 m m/ y ea r (B er t li n g, pe r so n al co m mu n ic a ti o n, 19 9 8) . T h is lo w er gr o wt h ra te is a c c o m p a n i e d b y a l o w e r r a t i o o f l o w - v e r s u s h i g h - d e n s i t y b a n d t h i c k n es s , w hi c h in mod e rn zo o xa n th e ll at e re ef co r al s ra ng e s fro m 0. 8 to 5, whe r ea s i n U p p e r J u r a s s i c t a x a t h e r a t i o s av e r a g e ar o u n d 1 an d ne v e r ex c e e d 1. 6 . T h i s s h o w s t h a t de s p i t e a di f f e r e n t ca l c i f i c a t i o n pa t t e r n du e t o el e v a t e d l i g h t a v a i l a b i l i t y , th e r e wa s no ma j o r pu s h in gr o w t h r a t e , s u g g e s t i n g th a t th e p h o t o s y m b i o t i c r e l a t i o n s h i p w a s no t ye t as ef f e c t i v e as i n m o d e r n f o r m s . Co rals als o ma y ha ve been apoz ooxa nthe llat e, i.e.,s witc hing fro m zo o xa n t h e l l a t e t o n o n z o o x a n t h e l l a t e st a t e ( S t a n l e y , p e r s o n a l c o m m u n i c a t i o n , 1 9 9 8 ) . Another important argument is that highest species diversity of Upper Ju r a s s i c c o r a l a s s o c i a t i o n s ap p e a r s i n s e t t i n g s wi t h a hi g h l y r e d u c e d y e t cl e a r l y noticeable siliciclastic influx rather than in pure carbonate settings (S e c t i o n 2 . 4 . 4 ) . A g a i n , t h i s i n d i c a t e s t h a t t h e p h o t o s y m b i o t i c r e l a t i o n w a s no t y e t p e r f e c t e d so t h a t t h e s e c o r a l s w e r e n o t y e t a d a p t e d t o st r o n g l y o l i g o t r o p h i c

Jurassic Reef Ecosystems

263

s e t t i n g s a n d m o d e r a t e l y o l i g o t r o p h i c t o m e s o t r o p h i c si t e s w e r e p r e f e r r e d f o r a t l e a s t s o m e U p p e r Ju r a s s i c c o r a l a s s o c i a t i o n s . 2 . 3 . 1 b . S e d i m e n t a t i o n Ra t e . I n co n t r a s t t o t h e ab o v e - m e n t i o n e d po s i t i v e e f f e c t o f a v e r y l o w t e r r i g e n e o u s i n f l u x , r a i s e d se d i m e n t a t i o n r a t e s w e r e a s j us t a th r ea t to Ju ra s si c co ra l s as the y ar e to mod e rn on e s (Ro g er s , 199 0 ; Ri e g l , 1 9 9 5 ) a n d st r o n g l y e l e v a t e d se d i m e n t a t i o n r a t e s c o u l d n o t b e t o l e r a t e d . N ev e rt h el e ss , th er e wa s a co ns i de r ab l e ran g e of tol e ra b le ba c kg r ou n d se d i m e n t a t i o n a m o n g Ju r a s s i c c o r a l s . I n g e n e r a l , c o r a l g r o w t h f o r m s a n d c a l i c a l t y p e s m a y be ad a p t e d t o s e d i m e n t a t i o n t o a va r i a b l e de g r e e . G r o w t h f o r m s t r a t e g i e s a r e st r a i g h t f o r w a r d , w i t h c y l i n d r i c a l so l i t a r y f o r m s a n d b u s h y c o r a l s b e t t e r a d a p t e d th a n ma s s i v e co l o n i e s . Am o n g ma s s i v e co l o n i e s , do m a l fo r m s ar e le s s v u l n e r a b l e th a n fl a t , en c r u s t i n g , or pl a t e - s h a p e d co r a l s . Al s o , nu m be r of se p t a e ( a s an ex p r e s s i o n o f av a i l a b l e t e n t a c l e s t h a t ca n be us e d f o r cl e a n i n g ) an d c a l i c a l t y p e s of m a s s i v e co l o n i e s m a y be go o d i n d i c a t o r s of po t e n t i a l ad a p t a t i o n . C e r i o i d f o r m s wi t h de e p c a l i c e s an d s t r o n g ca l i c a l wa l l s ar e po o r l y a d a p t e d , w h e r e a s t h a m n a s t e r o i d a n d m e a n d r o i d sh a p e s p o s e f e w e r p r o b l e m s i n s o r t i n g o u t u n w a n t e d p a r t i c l e s b y t e n t a c l e a c t i v i t y ( H u b b a r d a n d P o co c k , 1 9 7 2 ; Le i nf e ld e r, 19 8 6, 19 9 4b ) . How e ve r , the r e are ma n y exc e pt i on s to su c h m o r p h o l o g i c a l co n c e p t s . P o o r l y ad a p t e d co r a l s m i g h t ha v e gr o w n un d e r t h e s h e l t e r o f l a r g e r a n d b e t t e r - a d a p t e d f o r m s . Co l o n i a l sk e l e t a l m o r p h o l o g i e s m u s t a l s o e x p r e s s f a c t o r s o t h e r t h a n se d i m e n t a t i o n , su c h a s i l l u m i n at i o n . C o r a l l u m sh a p e s a r e m u l t i f u n c t i o n a l a n d m a y r e p r e s e n t a b e s t - f i t c o m p r o m i s e t o w a r d di f f e r e n t ad a p t a t i o n s . A n ex a m p l e ar e t h e do m i n a n t l y pl a t y s h a p e s of m a n y m i c r o s o l e n i d a s s o c i a t i o n s i n t e r p r e t e d as a l o w - l i g h t ad a p t a t i o n in de e p e r o r tur b id se t ti n gs (B e rt l in g , 199 7 b; Er r en s t, 19 9 0a , b; Le i nf e ld e r e t al. , 19 93 a , 1 99 6 ; Ins a la c o, 19 9 6a ) . Mic r os o le n id s ha ve be e n com p ar e d wit h th e mod e rn z o o x a n t h e l l a t e t a b u l a r d e e p - w a t e r fo r m L e p t o s e r i s f r a g i l i s ( L e i n f e l d e r , 1 9 9 2 ; I ns a la c o, 19 9 6a ) . Lep t os e ri s fr ag i li s oc cu r s dow n to 150 m in th e cle a r wat e rs of t he Re d Se a by com b in i ng bo t h a ve ry so p hi s ti c at e d ind i re c t pho t os y mb i ot i c r el a ti o ns h ip an d en ha n ce d su sp e ns i on fe e di n g mor p ho l og i es (S c hl i ch t er , 19 92 ) . I n s a l a c o ( 1 9 9 6 a ) p r e s e n t e d a k e y st u d y o n su c h a s s o c i a t i o n s b a s e d o n c o m p a r a t i v e st u d y o f oc c u r r e n c e s fr o m ea s t e r n Fr a n c e , S w i t z e r l a n d , an d E n g l a n d . He al s o i n t e r p r e t e d pu r e ca r b o n a t e , l o w - d i v e r s i t y m i c r o s o l e n i d a s s o c i a t i o n s w i t h p l a t e sh a p e d o m i n a n c e a s d e e p e r w a t e r se t t i n g s , w h e r e a s t h e , , m i c r o s o l e n i d wi n d o w ì wa s r a i s e d i n ar e a s wi t h t e r r i g e n e o u s i n f l u e n c e du e t o t u r b i d w a t e r s . H o w e v e r , su c h i n t e r p r e t a t i o n m i g h t b e b i a s e d d u e t o t w o d i m e n s i o n a l i n t e r p r e t a t i o n of g r o w t h f o r m s . Ac t u a l l y , d e t a i l e d an a l y s i s of g r o w t h f o r m s f r o m t h e S w i s s a n d F r e n c h o c c u r r e n c e s sh o w e d t h a t m i c r o s o l e n i d s ar e no t ge n e r a l l y pl a t y , bu t co m m o n l y ex h i b i t i n t e r m i t t e n t pu s t u l a r g r o w t h , en a b l i n g ca l i c a l gr o w t h t o ke e p up wi t h ep i s o d e s of s ed i me n ta t io n ( T a k a c s a n d S t u t t g a r t , u n p u b l i s h e d r e su l t s ) . T h r e e - d i m e n s i o n a l r e c o n s t r u c t i o n b a s e d o n pa r a l l e l s l a b s sh o w s t h a t ma n y pl a t y gr o w t h fo r m s me a s u r e d fr o m t w o - d i m e n s i o n a l sl a b s a c t u a l l y r e f e r t o b r o a d f u n n e l - s h a p e d t o i r r e gu l a r c o l o n i e s ( F i g . 4 ) , w h i c h r e p r e s e n t t h e b e s t a d a p t a t i o n a l f i t t o w a r d ( 1 ) su r f a c e e nl a rg e me n t nec e ss a ry be c au s e of tur b id i ty , (2 ) rem o va l po ss i bi l it i es of al l oc h -

264

Ch a p te r 8

t h o n o u s m a t e r i a l s e t t l i n g d o w n f r o m t h e w a t e r c o l u m n , a n d ( 3 ) r a p i d up w a r d g r o w t h t o c o p e w i t h se d i m e n t a t i o n . B e r t l i n g ( 1 9 9 7 b ) , i n an Ox f o r d i a n ex a m p l e f r o m no r t h e r n Ge r m a n y , p o i n t e d ou t t h a t bi o s t r o m e s co m p o s e d of pl a t y co r a l s al s o m a y de v e l o p un d e r s t r o n g s e d i m e n t s t r e s s , w h e n s e d i m e n t a t i o n i s i n t e r m i t t e n t . G r o w t h ba n d i n g s h o w s t h a t co r a l gr o w t h i s l i m i t e d t o ab o u t 20 ye a r s of no n s e d i m e n t a ti o n , w h e r e a s s t r o n g se d i m e n t p u l s e s a r e r e f l e c t e d b y t h e si l i c i c l a s t i c m a t r i x . I n m a n y ot h e r ca s e s , h o w e v e r , m i c r o s o l e n i d s un d e r w e n t m o r e f r e q u e n t , p ro b a b l y s e a s o n a l t e r r i g e n e o u s i n f l u x , t r i g g e r i n g t h e i r r e g u l a r , b r o a d f u n n e l sh a p e s d e s c r i b e d a b o v e . Mo r e o v e r , c o r a l c a l i c e s a l s o m a y b e o r i e n t e d d o w n w a r d , r e j e c t i n g t h e si m p l i f i e d l o w - l i g h t t h e o r y f o r b r o a d e n e d m i c r o s o l e n i d c o r a l s . I n S w i t z e r l a n d an d F r a n c e , c l a y e y m i c r o s o l e n i d as s o c i a t i o n s ar e ov e r l a i n by pu r e c a r b o n a t e m i c r o s o l e n i d as s o c i a t i o n s , bo t h d o m i n a t e d by br o a d e n e d , t w o d i m e n s i o n a l p l a t y g r o w t h f o r m s . T h e y o c c u r w i t h i n a g e n e r a l l y sh a l l o w i n g u p w a r d su c c e s s i o n a n d i t a p p e a r s t h a t t h e l o w e r , c l a y e y a s s o c i a t i o n g r e w i n d e e p e r w a t e r s t h a n t h e c o m p o s i t i o n a l l y d i s t i n c t , su p e r i m p o s e d , c a l c a r e o u s a s s o c i a t i o n ( L a t e r n s e r , 20 0 0 ) , wh i c h is a c o n t r a s t i n g v i e w to th e i n te r p r e t a t i o n o f I n s a l a c o ( 1 9 9 6 a ) . T h i s n e w i n t e r p r e t a t i o n i s c o r r o b o r a t e d b y t h e oc c u r r e n c e o f d i a g n o s t i c sh a l l o w - w a t e r o r g a n i s m s , su c h a s L i t h o c o d i u m a n d B a c i n e l l a ( s e e S e c t i o n 2. 3 . 4 ) , by a do m i n a n t l y bi o c l a s t i c gr o u n d m a s s an d by ec h i n o i d t y p e s i n d i c a t i v e of el e v a t e d wa t e r en e r g y ( s e e S e c t i o n 2. 3 . 3 ) . B e s i d e s ge n e r a l gr o w t h an d ca l i c a l f o r m s of co r a l s , ad d i t i o n a l cr i t e r i a ar e n e c e s s a r y t o i d e n t i f y t h e d e g r e e o f se d i m e n t a t i o n r a t e i n a Ju r a s s i c c o r a l a s s o c i a t i o n , p a r t i c u l a r l y si n c e m a n y m o d e r n c o r a l s h a v e a g o o d c a p a bi l i t y o f c l e a n i n g t h e m s e l v e s t h r o u g h m u c u s se c r e t i o n . T h i s h a s n o d i r e c t e x p r e s s i o n i n t h e m o r p h o l o g y of t h e co r a l l i t e or t h e ge n e r a l gr o w t h f o r m . Ot h e r u s e f u l c r i t e r i a ar e : • C o r a l s m a y sh o w s t e p l i k e r u g g e d u n d e r s i d e s o r n o n e n v e l o p i n g g r o w t h b a n d s t h a t de m o n s t r a t e t h a t co r a l s be c a m e p a r t i a l l y bu r i e d wh i l e g r o w i n g . Ru g g e d m a r g i n s a r e i n d i c a t i v e o f o c c a s i o n a l se d i m e n t a r y e v e n t s , w h e r e a s sm o o t h m a r g i n s w i t h n o n e n v e l o p i n g g r o w t h b a n d a r e c h a r a c t e r i s t i c o f c o n t i n u o u s l y e l e v a t e d se d i m e n t a t i o n ( N o s e a n d L e i n f e l d e r , 19 9 7 ) . • T h i c k m i c r o b i a l c r u s t s w i t h f r e q u e n t m i c r o e n c r u s t e r s o n c o r a l su r f a c e s a r e g o o d i n d i c a t o r s o f v e r y r e d u c e d b a c k g r o u n d se d i m e n t a t i o n . • M i c r o e n c r u s t e r s al o n e or as s o c i a t e d wi t h t h i n m i c r o b i a l cr u s t s m i g h t be i n d i c a t i v e o f st r o n g l y r e d u c e d b u t i n t e r m i t t e n t se d i m e n t a t i o n . • V e r y l o w d i v e r s i t i e s o f c o r a l a s s o c i a t i o n s p o i n t st r o n g l y t o se d i m e n t a t i o n st r e s s , if ot h e r st r e ss fa c t o r s , su c h as gr e a t de p t h , st r o n g a b r as i o n , or a b n o r m a l sa l i n i t i e s c a n b e r u l e d o u t . 2 . 3 . l c . W a t e r E n e r g y . T h e r e a r e so m e a d d i t i o n a l d i f f e r e n c e s b e t w e e n J u r a s s i c an d mo d e r n co r a l s an d co r a l as s o c i a t i o n s . Th e do m i n a n c e of di s t i n c t m o r p h o l o g y i n c o m p a r a b l e h y d r a u l i c se t t i n g s i s n o t c o m p a t i b l e b e t w e e n

Ju rassi c Reef Eco sy st ems

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J u r a s s i c a n d m o d e r n c o r a l s . Ju r a s s i c h i g h - e n e r g y se t t i n g s a r e d o m i n a t e d b y m a s s i v e he m i s p h e r i c a l r a t h e r t h a n br a n c h i n g f o r m s as i n m o d e r n co r a l r e e f s . I n t h e Ju r a s s i c , b r a n c h i n g f o r m s w e r e l a r g e l y r e s t r i c t e d t o l o w e r e n e r g y s e t t i n g s . H o w e v e r , so m e sp e c i e s o f C a l a m o p h y l l i o p s i s , S t y l o s m i l i a , a n d D e r m o s m i l i a d o oc c u r i n hi g h e r - e n e r g y r e e f s of P o r t u g a l an d L o r r a i n e ( F r a n c e ) , w h i c h c o u l d i n d i c a t e st r a t e g i e s s i m i l a r t o m o d e r n a c r o p o r oi d s , su c h a s r a p i d r e g e n e r a t i o n p o t e n t i a l a f t e r st o r m s . F l a t e n c r u s t i n g f o r m s , w h i c h m a y o c c u r i n m o d e r n , h i g h l y a b r a s i v e se t t i n g s , a r e n o t si m i l a r l y d e v e l o p e d i n J u r a s s i c r e e f s o w i n g t o t h e f a c t t h a t su c h e n v i r o n m e n t s w e r e n o r m a l l y u n s u i t a b l e f o r co l o n i z a t i o n ( s e e S e c t i o n 2. 3 . 5 ) . Ho w e v e r , l o a f - s h a p e d , br o a d , n o n e n c r u s t i n g m o r p h o l o g i e s a r e a t y p i c a l e l e m e n t o f u n s t a b l e , sa n d - gr o u n d , h i g h - e n e r g y r e e f s a n d p r o b a b l y r e p r e s e n t st a b i l i z a t i o n st r a t e g i e s b y a b r o a d , l o w e r r e s t i n g su r f a c e . 2 . 3 . 1 d . S a l i n i t y . A f e w Ju r a s s i c c o r a l t a x a w e r e v e r y e u r y h a l i n e . A m p h i a s t r e a p i r i f o r m i s , f o r i n s t a n c e , f o r m e d sm a l l , m o n o s p e c i f i c r e e f b o d i e s u p t o 1 m l a r g e i n an oy s t e r — I s o g n o m o n a s s o c i a t i o n wi t h i n de l t a em b a y m e n t s i n Ki m m e r i d g i a n an d T i t h o n i a n r o c k s of P o r t u g a l ( F ¸ r s i c h , 19 8 1 ; F ¸ r s i c h an d W e r n e r , 19 8 6 ; L e i n f e l d e r , 19 8 6 ) . 2 . 3 . 1 e . T e m p e r a t u r e . N o Ju r a s s i c c o l d - w a t e r c o r a l s a r e k n o w n . A s t o n i s h i n g co r a l p r o d u c t i v i t y oc c u r r e d i n f a i r l y hi g h pa l e o l a t i t u d e s ( e . g . , G e r m a n y : Be r t l i n g , 1 9 9 3 , 1 9 9 7 b ; S o u t h e r n E n g l a n d : I n s a l a c o e t a l . , 1 9 9 7 ) . L o w c o r a l d i v e r s i t i e s o f so u t h e r n A r g e n t i n e a n O x f o r d i a n c o r a l a s s o c i a t i o n s a r e i n t e r p r e t e d a s t h e r e s u l t o f si l t a t i o n st r e s s ( M o r s c h , 1 9 8 9 ) , r a t h e r t h a n c l i m a t i c s t r e s s , si n c e c o r a l c o l o n i e s a r e l a r g e a n d c o - o c c u r w i t h d a s y c l a d a c e a n a l g a e a n d c a l c a r e o u s o o l i t e s ( M o r s c h , 1 9 8 9 ; Ma t h e o s a n d Mo r s c h , 1 9 9 0 ; L e g g a r e t a , 1991). 2 . 3 . 2 . M u l t i p u r p o s e W o r k e r s : Th e S p o n g e s M o s t o f t h e sp o n g e s i n m o d e r n r e e f s a r e so f t sp o n g e s b e l o n g i n g t o t h e d e m o s p o n g e g r o u p . M u c h r a r e r a r e c o r a l l i n e sp o n g e s t h a t e x h i b i t a b a sa l c o r a l s k e l e t o n , a r e n o r m a l l y sm a l l , a n d o f t e n a r e r e s t r i c t e d t o r e e f c a v e s . T h e s po n ge s ar e oft e n des c ri b ed as th e wa te r fi lt e r sys t em of th e re ef , by th ei r a bi l it i es to fi l te r hu ge am o un t s of wat e r in ord e r to fee d on ba ct e ri a , a pr i n c i p a l f o o d so u r c e . T h e y a l s o se r v e p a r t l y t o st a b i l i z e l o o s e su b s t r a t e s t h a t su b s e q u e n t l y b e c o m e c e m e n t e d b y o t h e r o r g a n i s m s , r e d u c i n g a b r a s i v e i n f l u en c e o f s a n d - s i z e d p a r t i c l e s w i t h i n t h e r e e f ( G r e b e t a l . , 1 9 9 6 ) . Ma n y m o d e r n sp o n g e s l i v e ou t s i d e m o d e r n co r a l r e e f s i n ne a r l y a l l wa t e r de p t h s . T h e h o m e of m o s t m o d e r n si l i c e o u s sp o n g e s ( l i t h i s t i d d e m o s p o n g e s a n d h e x a c t i n o s a n sp o n g e s ) a r e de e p e r wa t e r s , do w n t o ba t h y a l de p t h s ( R e i d , 19 6 8 ; co m p i l a t i o n of a d d i t i o n a l r e f e r e n c e s i n K r a u t t e r , 1 9 9 7 ) . O n l y r a r e l y d o t h e y f o r m sil i c e o u s s p o n g e m e a d o w s ( H e n r i c h e t al . , 1 9 9 2 ) , an d on l y a f e w l o c a l i t i e s ar e kn o w n t o d a t e w h e r e r i g i d h e x a c t i n o s a n s p o n g e s o c c u r i n d e e p sh e l f m u d m o u n d s

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( C o n w a y e t a l . , 1 9 9 1 ; C o n w a y an d Ba r r i e , 1 9 9 7 ) . Ho w e v e r , t h e l a t t e r l o c a l i t y i s n o t a d i r e c t a n a l o g u e t o Ju r a s s i c si l i c e o u s sp o n g e m u d m o u n d s b e c a u s e t h e m o d e r n ex a m p l e i s c o m p o s e d of t e r r i g e n e o u s m u d , wh e r e a s t h e m u d i n t h e J u r a s s i c ex a m p l e s i s l a r g e l y c a r b o n a t e . Re c e n t l y , P i s e r a ( 1 9 9 7 ) p o i n t e d t o s o m e p o s s i b l e m o d e r n a n a l o g u e s f o r si l i c e o u s sp o n g e se t t i n g s o n d e e p e r c a r b o n a t e - d o m i n a t e d sh e l v e s , su c h a s t h e b a t h y a l l i t h i s t i d a s s o c i a t i o n s o n t h e s l o p e s o f Ne w Ca l e d o n i a ( L È v i a n d L È v i , 1 9 8 8 ; Ro u x e t a l . , 1 9 9 1 ) . D e t a i l e d a n a l y s i s i s st i l l l a c k i n g a n d f u r t h e r st u d i e s w i l l sh o w w h e t h e r t h e s e o c c u r r e n c e s c o u l d s e r v e a s m o d e l s f o r Ju r a s s i c sp o n g e r e e f s . T o d a t e , i t a p p e a r s t h a t n o n e o f t h e k n o w n m o d e r n sp o n g e se t t i n g s a r e d i r e c t l y c o m p a r a b l e w i t h t h o s e o f t h e Ju r a s s i c , p a r t i c u l a r l y t h e sp e c t a c u l a r sp o n g e m o u n d s. W h e r e a s n o t m u c h i s k n o w n a b o u t Ju r a s s i c so f t sp o n g e s , t h o s e w i t h a r i g i d s k e l e t o n o c c u r f r e q u e n t l y i n Ju r a s s i c r e e f s . I n c o r a l r e e f s , s t r o m a t o p o r o i d s ( n o w g e n e r a l l y a s s i g n e d t o t h e c o r a l l i n e sp o n g e s t h a t h a v e a n i d e n t i c a l b a s a l c a l c a r e o u s sk e l e t o n ) a n d o t h e r sp o n g e s w i t h c a l c a r e o u s s k e l e t o n s ( C a l c a r e a ) ar e co m m o n el e m e n t s an d oc c a s i o n a l l y ev e n do m i n a t e t o f o r m m e a d o w s ( F ¸ r s i c h an d We r n e r , 19 9 1 ; We r n e r e t a l . , 1 9 9 4 ) . Ne a r l y al l o f t h e m a r e r e s t r i c t e d t o sh a l l o w w a t e r . S i l i c e o u s sp o n g e s a r e r a r e i n Ju r a s s i c c o r a l r e e f s b u t a r e t h e d o m i n a n t e l e m e n t i n t h e sp o n g e r e e f s . I n g e n e r a l , t h e r e m a y be ei t h e r a do m i n a n c e of l i t h i s t i d s wi t h ad d i t i o n a l he x a c t i n o s a n el e m e n t s o r a d o m i n a n c e o f h e x a c t i n o s a n s w i t h o u t l i t h i s t i d s . T a x a d i v e r s i t y ra n g e s f r o m h i g h t o ve r y r e d u c e d , wi t h di s t i n c t gr o w t h f o r m s cl e a r l y pr e d o m i n a t i n g in th e l o w - d i v e r s i t y a s s o c i a t i o n s ( d i s h sh a p e d o m i n a n c e o r t u b e - v a s e sh a p e d o m i n a n c e ; se e S e c t i o n 2 . 4 . 4 ) . T h e b i o l o g y o f m o d e r n si l i c e o u s sp o n g e s i s n o t f u l l y u n d e r s t o o d . R e c e n t l y , K r a u t t e r ( 1 9 9 7 ) c o m p i l e d a v a i l a b l e d a t a o n m o d e r n sp o n g e s a n d , b a s e d o n b o t h m o d e r n a n d Ju r a s s i c e x a m p l e s , d e v e l o p e d m o r p h o l o g i c a l c r i t e r i a t o h i g h l i g h t d e m a n d s a n d a b i l i t i e s o f J u r a s s i c s p o n g e s . O f pa r t i c u l a r i n t e r e s t i s t h a t t h e t w o m a j o r g r o u p s o f si l i c e o u s sp o n g e s d i f f e r c o ns i d e r a b l y i n t h e i r bi o l o g y an d ph y s i o l o g y . 2 . 3 . 2 a . E n e r g y U p t a k e . T h e n o r m a l f e e d i n g st r a t e g y o f sp o n g e s i s a c t i v e f i l t e r i n g of mi n u t e pl a n k t i c or g a n i c ma t t e r . Si n c e os t i a ar e ra r e l y la r g e r th a n 2 0 0 µ m , t h e u s a b l e p a r t i c l e si z e i s b e l o w t h i s l i m i t , d o w n t o 1 µ m ; h e n c e , s p o n g e s l a r g e l y f i l t e r on t h e m i c r o - , na n n o - , an d pi c o p l a n k t o n , mo s t of wh i c h a r e w f r e e l i v i n g ba c t e r i a . T h e am o u n t of f r e e b a c t e r i a r a p i d l y di m i n i s h e s i n g r e a t e r wa t e r de p t h ( H o b b i e e t al . , 1 9 7 2 ; R h e i n h e i m e r , 19 8 0 ) , a f a c t f o r wh i c h s p o n g e s co m p e n s a t e by en o r m o u s wa t e r pu m p i n g ac t i v i t y o r by ad d i t i o n a l f or m s of ene r gy up t ak e . Man y sp on g es of th e de mo s po n ge gr o up (i n cl u di n g t h e i m p o r t a n t Ju r a s s i c l i t h i s t i d sp o n g e s ) c u l t i v a t e e n o r m o u s a m o u n t s o f b a c t e r i a o r c y a n o b a c t e r i a , w h i c h c a n a m o u n t t o m o r e t h a n 8 0 % o f t h e so f t t i s s u e o f s p o n g e s . T h i s a p p e a r s a u s e f u l st r a t e g y t o d e a l w i t h m a j o r st r o n g f l u c t u a t i o n s i n n u t r i e n t a v a i l a b i l i t y . W h e r e a s t h e sy m b i o t i c r e l a t i o n s h i p w i t h c y a n o b a c t e r i a i s e v i d e n t ( W i l k i n s o n a n d T r o t t , 1 9 8 5 ; W i l k i n s o n a n d E v a n s , 1 9 8 9 ) , t h e sa m e i s a l s o p l a u s i b l e f o r t h e se t t l e m e n t o f p u r e b a c t e r i a . Ba c t e r i a p r o b a b l y b e n e f i t f r o m t h e ch e m i c a l m i c r o e n v i r o n m e n t an d t h e wa s t e pr o d u c t s of t h e ho s t

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s p o n g e , w h e r e a s t h e sp o n g e c a n f e e d o n m e t a b o l i c p r o d u c t s o f t h e b a c t e r i a o r t h e ba c t e r i a t h e m s e l v e s , es p e c i a l l y i n t i m e s of r e d u c e d av a i l a b i l i t y of ex t e r n a l f o o d . T h i s st r a t e g y e n a b l e s t h e m t o i n h a b i t e n v i r o n m e n t s t h a t a r e d e p l e t e d i n e x t e r n a l pl a n k t i c f o o d . I n f o s s i l ex a m p l e s , l i t h i s t i d s p o n g e s wi t h ve r y l a r g e t h i c k b o d y w a l l s ap p e a r t o h a v e u s e d t h i s s t r a t e g y . T h i s i s p a r t i c u l ar l y o b v i o u s i f i n m o r p h o v a r i a b l e f o r m s t h e sa m e sp e c i e s a p p e a r s t h i n i n so m e e n v i r o n m e n t s b u t t h i c k e n e d a n d g l o b o i d i n o t h e r se t t i n g s . I n l i t h i s t i d d o m i n a t e d as s o c i a t i o n s , l o w nu t r i e n t av a i l a b i l i t y m a y b e i n d i c a t e d i f : -

T h i c k - w a l l e d f o r m s do m i n a t e , wh e r e a s th i n - w a l l e d , mo r p h o c o n s t a n t f o r m s a r e mi s s i n g . M o r p h o v a r i a b l e f o r m s a r e o f t h e n o d u l a r t o g l o b o i d , i . e . , t h e h i g h v o lu m e p e r - s u r f a c e ty p e . T h e di v e r s i t y of t h e en t i r e as s o c i a t i o n i s l o w .

H e x a c t i n e l l i d sp o n g e s h a v e a c o m p l e t e l y d i f f e r e n t b a u p l a n , a n d t h u s a r e c o n s i d e r e d a n i n d e p e n d e n t p h y l u m b y so m e a u t h o r s ( d i s c u s s i o n i n Re i s w i g a n d Ma c k i e , 1 9 8 3 ) . T h e v o l u m e o f t h e i r o r g a n i c t i s s u e i s e x t r e m e l y t h i n , j u s t c o a t i n g t h e si l i c a sp i c u l e sk e l e t o n . T h e i r f i l t e r - f e e d i n g c a p a c i t y i s m u c h p o o r e r t h a n i n l i t h i s t i d s p o n g e s , bu t t h e i r t i s s u e ch a r a c t e r i s t i c s en a b l e t h e m t o f e e d l a r g e l y on di s s o l v e d an d co l l o i d a l or g a n i c m a t t e r by os m o t r o p h y . Di s s o l v e d a n d c o l l o i d a l o r g a n i c m a t t e r b e c o m e st r o n g l y e n r i c h e d i n d e e p e r w a t e r s t h r o u g h t h e d e c a y o f si n k i n g d e a d p l a n k t o n a n d o t h e r o r g a n i c p a r t i c u la r m a t e r i a l . D i s s o l v e d o r g a n i c m a t e r i a l i n sh a l l o w w a t e r i s r e c y c l e d d i r e c t l y b y t h e we a l t h of un i c e l l u l a r li v i n g pl a n k t o n t h a t is la c k i n g la r g e l y i n de e p e r w a t e r , m a k i n g d e e p e r se t t i n g s t h e p r e f e r e n t i a l si t e o f h e x a c t i n e l l i d g r o w t h . E v e n if di s s o l v e d o r g a n i c ma t e r i a l is r a r e du e to ge n e r a l lo w pr o d u c t i v i t y of t h e su r f a c e wa t e r s or fr o m th e r m o h a l i n e st r a t i f i c a t i o n pr e v en t i n g d e a d ma t e r i a l f r o m si n k i n g t o t h e b o t t o m , so m e h e x a c t i n e l l i d s c a n st i l l a d a p t t o su c h i m p o v e r i s h e d c o n d i t i o n s b y e n l a r g i n g t h e i r su r f a c e - t o - v o l u m e r a t i o . S u p e r o l i g o t r o p h i c c o n d i t i o n s ar e t o be as s u m e d by t h e f o l l o w i n g cr i t e r i a : -

S t r o n g d o m i n a n c e o f t h i n - b o d i e d , d i s h - s h a p e d h e x a c t i n e l l i d sp o n g e s . I f n o n m o r p h o v a r i a b l e , o n l y su c h t a x a w i t h a n o r i g i n a l t h i n d i s h - s h a p e a r e r epr ese nted. I f l i t h i s t i d sp o n g e s a r e p r e s e n t , t h e y a r e o f t h e m a s s i v e t o n o d u l a r t y p e ( F i g . 6). L o w - t o ve r y - l o w - d i v e r s i t y as s o c i a t i o n s , wi t h ha r d l y an y ad d i t i o n a l f a u n a l element s.

S u c h a pe c u l i a r as s o c i a t i o n i s kn o w n f r o m t h e Ox f o r d i a n of ea s t e r n S pa i n ( s e e S e c t i o n 2. 4 . 4 ) . 2 . 3 . 2 . b . S e d i m e n t a t i o n R a t e . S p o n g e s , l i k e a n y o t h e r fi x o s e s s i l e o r g a n i s m , a r e v u l n e r a b l e t o e l e v a t e d se d i m e n t a t i o n r a t e s b u t h a v e a v a r i e t y o f a d a p t a t i o n s t h a t ar e al s o r e c o g n i z e d i n f o s s i l ex a m p l e s an d he l p de f i n e t h e a n c i e n t e n v i r o n m e n t w h e r e sp o n g e a s s o c i a t i o n s l i v e d . D e v e l o p m e n t o f a t u b e s h a p e i s o n e o f t h e p r i m a r y a d a p t a t i o n s t o w a r d se d i m e n t a t i o n . T u b e sh a p e

FIGURE 6. Selected environmental factors controlling morphologies of Jurassic siliceous sponges (strongly simplified). Dominance of morphologies varies from thin dishes to thick-walled knobs, to cup and tube shape along environmental gradients. Distinct trends may occur along increasing water energy and increasing sedimentation, which is normally coupled with increasing nutrient availability. Note that dominance of tube shapes may both be indicative of slightly elevated water energy and elevated sedimentation. See text for details.

h e l p s i n f i l t e r i n g t h r o u g h t h e , , c h i m n e y ì ( B e r n o u l l i ) e f f e c t , p r o v i d e d sl o w h o r i z o n t a l c u r r e n t s a r e a v a i l a b l e . I n c o m p l e t e l y q u i e t se t t i n g s , t h e e x h a l a n t c u r r e n t b e c o m e s b u n d l e d i n t u b e - s h a p e d sp o n g e s , a n d t h u s p r e v e n t s f i n e m a t e r i a l f r o m se t t l i n g d o w n . A s s o c i a t i o n s o f sm a l l , t u b e - a n d n a r r o w v a s e s h a p e d sp o n g e s o c c u r f r e q u e n t l y ( L e i n f e l d e r e t a l . , 1 9 9 3 a ; F ¸ r s i c h a n d W e r n e r , 1 9 9 1 ; W e r n e r e t u l . , 1 9 9 4 ) . D i s h - s h a p e d sp o n g e s a r e c o m p l e t e l y u n p r o t e c t e d . H o w e v e r , t h e sp o n g e s d o h a v e s o m e a b i l i t i e s t o c l e a n s e t h e m s e l v e s o f m a t e r i a l t h a t a c t u a l l y p e n e t r a t e s t h e sp o n g e . D e m o s p o n g e s h a v e m u l t i p u r p o s e c e l l s , t h e so - c a l l e d a r c h a e o c y t e s , w h i c h c a n c a p t u r e u n w a n t e d p a r t i c l e s , t r a n s p o r t t h e m t o t h e o u t e r su r f a c e o f t h e sp o n g e , a n d r e l e a s e t h e m t h e r e , al t h o u g h t h i s do e s no t wo r k we l l i n l i t h i s t i d d e m o s p o n g e s b e c a u s e t h e d e n s e n e s s o f t h e i r sp i c u l a r sk e l e t o n st r o n g l y r e s t r i c t s m o t i l i t y o f ar c h a e o c y t e s . Co n s e q u e n t l y , t h i s g r o u p o f d e m o s p o n g e s i s l a r g e l y r e s t r i c t e d t o c l e a r w a t e r s . H e x a c t i n o s a n sp o n g e s h a v e t h e a b i l i t y t o l e t pa r t i c l e s m i g r a t e t h r o u g h t h e i r t i s s u e s , al t h o u g h t h e pr o c e s s an d e s p e c i a l l y t h e l i m i t a t i o n s of i t ar e no t ye t f u l l y un d e r s t o o d ( K r a u t t e r , 19 9 7 ) . Y e t , t h e f o s s i l e x a m p l e s sh o w t h a t h e x a c t i n o s a n s a r e o f t e n t h e o n l y s p o n g e s a p p e a r i n g i n c l a y e y d e p o s i t s t h a t sh o w o t h e r f e a t u r e s o f e l e v a t e d

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s e d i m e n t a t i o n r a t e , su c h a s l a c k o f m i c r o b o l i t e c r u s t s ( s e e S e c t i o n 2 . 4 . 4 ) . A c o u p l e o f c a l c a r e o u s sp o n g e s w e r e a b l e t o c o v e r t h e i r l o w e r , o l d e r i nh a l a n t p o r e s b y a se c o n d a r y sk e l e t o n , h e n c e a l l o w i n g t h e m t o c o p e w i t h se d i m e n t a c c u m u l a t i o n . T h i s w a s d e t e c t e d i n t h e Ju r a s s i c sp o n g e E u d e a c l a v a t a b y K r a u t t e r (1 9 9 4 ) . 2 . 3 . 2 c . T e m p e r a t u r e . An o t h e r im p o r t a n t f e a t u r e of p a l e o e n v i r o n m e n t a l i m p l i c a t i o n is th e r e s t r i c t i o n of mo d e r n he x a c t i n o s a n s p o n g e s to wa te r t e m p e r a t u r e s co l d e r t h a n 1 5 o Ce l s i u s ( M a c k i e e t a l . , 1 9 8 3 ; D a y t o n e t a l . , 1 9 9 4 ) , al t h o u g h t h i s m i g h t be a n ev o l u t i o n a r y ad a p t a t i o n an d no t ne c e s s a r i l y t r a n s f e r a b l e t o t h e an c i e n t ex a m p l e s . 2 . 3 . 2 d . G r o w t h R a t e . T h e g r o w t h r a t e s o f sp o n g e s , t h o u g h p o o r l y k n o w n a n d a p p a r e n t l y v e r y v a r i a b l e , a p p e a r t o r a n g e a r o u n d t h e a v e r a ge o f 2 c m / y e a r f o r m o d e r n si l i c e o u s sp o n g e s ( M . K r a u t t e r , p e r s o n a l c o m m u n i ca t i o n , 1 9 9 8 ) . U p p e r Ju r a s s i c si l i c e o u s sp o n g e s o c c a s i o n a l l y m a y b e m o r e t h a n 2 m i n d i a m e t e r . S u c h i n d i v i d u a l s t h u s sh o u l d h a v e a t t a i n e d a n a g e o f se v e r a l h u n d r e d y e a r s , m a k i n g g r o w t h r a t e s a n d i n d i v i d u a l l i f e sp a n s c o m p a r a b l e t o s c l e r a c t i n i a n co r a l s . 2 . 3 . 3 . Bi o e r o d e r s : Th e R e c y c l e r s o f Bu i l d i n g Ma t e r i a l I n a m o d e r n r e e f a we a l t h of or g a n i s m s ar e co n t i n u o u s l y er o d i n g t h e co r a l s k e l e t o n s b y r a s p i n g , g n a w i n g , a n d b i t i n g o f f p i e c e s o f t h e s u r f a c e or e v e n b y d r i l l i n g i n t o t h e m . Mo s t b i o e r o d e r s , su c h a s h e r b i v o r o u s sn a i l s , p a r r o t f i s h , o r m a n y se a u r c h i n s a r e d o i n g so i n se a r c h o f f o o d , w h i c h i s o f t e n so f t a l g a e . P r o k a r y o t i c , m i c r o s c o p i c cy a n o b a c t e r i a an d f u n g i dr i l l i n t o co r a l s ke l e t o n s f o r p r o t e c t i o n , a s d o t h e f r e q u e n t l i t h o p h a g i d b i v a l v e s a n d b o r i n g sp o n g e s . B i o e r o d e r s ar e i m p o r t a n t an d i n a he a l t h y r e e f , t h e y ar e i n pe r f e c t eq u i l i b r i u m w i t h r e e f g r o w t h . T h e y r e m o v e o l d , si c k , a n d d e a d st o n e c o r a l s a n d o t h e r c a l c a r e o u s sk e l e t o n s b e f o r e t h e su r f a c e s a r e l o s t b y se t t l e m e n t o f a so f t a l g a l c o v e r . I f bi o e r o d e r s at t a c k l i v i n g co r a l s , i t i s pa r t i c u l a r l y t h e o l d on e s t h a t a l r e a d y su f f e r f r o m p a r t i a l n e c r o l y s i s , h e n c e g i v i n g t h e l a r v a e o f b o t h n o n d o m i n a t i n g an d d o m i n a t i n g ta x a im p r o v e d ch a n c e s fo r se t t l e m e n t . By d o i n g s o , th e y ma i n t a i n hi g h co r a l di v e r s i t y . Pa l e o z o i c re e f s of t e n sh o w ti m e d e p e n d e n t , i n t r i n s i c c h a n g e f r o m a p i o n e e r , t h r o u g h i n t e r m e d i a t e ( h ig h d i v e r s i t y ) t o a d o m i n a n c e st a g e , w i t h o u t a n y a p p a r e n t e x t r i n s i c e n v i r o n m e n t a l c h a n g e s ( e . g . , Wa l k e r an d Al b e r s t a d t , 19 7 5 ) . Ag i n g of a r e e f , as ex p r e s s e d by t h e i n t r i n s i c c h a n g e o f r e e f a s s o c i a t i o n s , i s l a r g e l y u n k n o w n f r o m Mes o z o i c a n d Ce n o z o i c r e e f s an d m i g h t b e an ex p r e s s i o n o f t h e m u c h l o w e r av a i l a b i l i t y o f bi o e r o d e r s dur i n g t h e P a l e o z oi c , an d he n c e t he l a c k of t h e , , r e j u v e n e s c a n c e ì m e c h a n i s m pr o v i d e d by th e s e or g a n i s m s . B i o e r o d e r s b r e a k t h e r e e f m a t e r i a l i n t o p a r t i c l e s o f v a r i a b l e si z e . C o b b l e a n d sa n d - s i z e d p i e c e s , i f c e m e n t e d b y o t h e r o r g a n i s m s , b e c o m e r e c y c l e d b y f or m in g a ha r d fou n da t io n fo r the ne w se tt l em e nt of la r va e . Mos t of th e s m a l l e r g e n e r a t e d m a t e r i a l , i n c l u d i n g s i l t - an d m u d - s i z e d bi o e r o d e d pa r t i c l e s , al s o i s

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r e m o v e d f r o m op e n s u r f a c e s in t h e r e e f . Pa r t of th i s ma t e r i a l f i l l s th e op e n c a v i t i e s o f t h e u n d e r l y i n g d e a d r e e f , a n d b y d o i n g so s t a b i l i z e s t h e e n t i r e l i v i n g re e f . A n o t h e r la r g e fr a c t i o n is wi n n o w e d in t o th e op e n oc e a n or th e l a g o o n b y w a v e s a n d st o r m s , t h u s p r e v e n t i n g t h e r e e f f r o m g e t t i n g c h ok e d b y i t s ow n de b r i s . T h i s is pa r t i c u l a r l y im p o r t a n t f o r pr o d u c t i v e r e e f s g r o w i n g in a n o n s u b s i d i n g t e c t o n i c se t t i n g . T h e a v a i l a b l e e c o s p a c e c a n b e u s e d m u c h l o n g e r b y t h i s st r a t e g y . I n Ju r a s s i c re e f s , qu i t e si m i l a r bi o e r o d i n g or g a n i s m s w e r e ac t i v e . Bo r i n g m i c r o b e s w e r e u b i q u i t o u s i n c o r a l r e e f s a n d b a c k r e e f s a n d s , a s e v i d en c e d b y t y p i c a l m i c r o c r y s t a l l i n e r i m s w i t h an i r r e g u l a r i n n e r m a r g i n ( c o a t e d gr a i n s p r o p a r t e ) . E v e n th e ol d e s t bo r i n g f o r a m i n i f e r , T r o g l o t e l l a in c r u s t a n s , k n o w n f r o m th e Ju r a s s i c , de v e l o p e d a pe c u l i a r co m m e n s a l li f e s t y l e wi t h i n th e te s t of a n o t h e r f o r a m i n i f e r an d di d no t co n t r i b u t e m u c h t o ge n e r a l bi o e r o s i on ( S c h m i d an d L e i n f e l d e r , 19 9 6 ) . L i t h o p h a g i d bi v a l v e s of t e n m i n e d m a s s i v e s k e l e t o n s t o t h e i r co m p l e t e d e s t r u c t i o n . Be r t l i n g ( 1 9 9 7 a ) d e m o n s t r a t e d t h a t t a x o n o m i c co m p o s i t i o n o f t h e b o r i n g f a u n a a l s o w a s r e l a t e d t o t h e d e gr e e o f sedimen tation. W h i l e c l i o n i d b o r i n g sp o n g e s w e r e n o t y e t a s i m p o r t a n t i n Me s o z o i c r e e f s a s i n N e o g e n e r e e f s ( B e r t l i n g , 1 9 9 7 a ) , t h e b o r i n g h a p l o s k l e r i d sp o n g e A k a w a s w i d e s p r e a d i n d e e p e r sp o n g e r e e f se t t i n g s ( R e i t n e r a n d K e u p p , 1 9 9 1 ) . S e a u r c h i n s a r e a v e r y f r e q u e n t e l e m e n t i n b o t h J u r a s s i c s p o n g e a n d c or a l r e e f s . I n r a r e c a s e s , sc r a t c h m a r k s f r o m se a u r c h i n s o n b i v a l v e sh e l l s a r e k n o w n f r o m t h e U p p e r Ju r a s s i c ( L e i n f e l d e r , 1 9 8 6 ) , p r o v i d i n g e v i d e n c e f o r t h e e x i s t e n c e o f a l g a l t u r f s o r m i c r o b i a l c o a t i n g s o n t h e s e sh e l l s . R e g u l a r e c h i n o i d s a r e f r e q u e n t i n m a n y Ju r a s s i c r e e f s c o n t a i n i n g m i c r o b i a l cr u s t s . A s i n m o d e r n r e e f s , t h e y ap p e a r t o ha v e ha d t h e t a s k of k e e p i n g g r o w t h o f m i c r o b i a l f i l m s u n d e r c o n t r o l . I n t e r e s t i n g l y , so m e c o r a l r e e f s d o sh o w a n u p w a r d a n d o u t w a r d i n c r e a s e o f m i c r o b i a l c r u s t s , w h i c h i s a s t o n i s h i n g l y pa r a l l e l e d by a r e l a t i v e de c r e a s e r a t h e r t h a n an i n c r e a s e of r e g u l a r se a u r c h i n s . D e s p i t e t h e p o t e n t i a l h i g h e r f o o d a v a i l a b i l i t y p r o v i d e d b y p r o l i f i c m i c r o b i a l gr o w t h , t h i s f a c t i n d i c a t e s en v i r o n m e n t a l de t e r i o r a t i o n at l e a s t f o r s e a u r c h i n s , s u c h a s i n t e r v a l s o f p o o r o x y g e n a t i o n , w h i c h ma n y h a v e s p e e d e d u p t h e t u r n o v e r f r o m c o r a l d o m i n a n c e t o e x c l u s i v e m i c r o b o l i te d o m i n a t i o n (s e e Se c t i o n 2. 4 . 1 ) . Al s o , se a u r c h i n s ar e l e s s fr e q u e n t in m o n o s p e c i f i c c o r a l r e e f m e a d o w s st r u g g l i n g w i t h se d i m e n t a t i o n . I t s e e m s t h a t i n t h e l a t t e r ex a m p l e t h e r e wa s t o o l i t t l e f o o d f o r t h e ur c h i n s be c a u s e t h e s t r a t e g y of t h e ph a c e l o i d t o r a m o s e co r a l s wa s t o ha v e t h e i r br a n c h e s p a r t i a l l y b u r i e d b y se d i m e n t ( s e e S e c t i o n 2 . 3 . 1 ) . T o da t e , i t i s i m p o s s i b l e t o ca l c u l a t e m a s s ba l a n c e bu d g e t s of r e e f c o n s t r u c t i o n v e r s u s r e e f d e s t r u c t i o n i n Ju r a s s i c r e e f s , a l t h o u g h b u lk a c c r e t i o n r a t e s c a n b e d e t e r m i n e d i n so m e c a s e s . N e v e r t h e l e s s , t h e p a t t e r n s s h o w t h a t b i o e r o s i o n w a s a n i m p o r t a n t f a c t o r i n Ju r a s s i c r e e f s a s w e l l . H o w e v e r , so m e J u r a s s i c b i o e r o d e r s m a y b e v a l u a b l e i n d i c a t o r s o f sp e c i f i c e n v i r o n m e n t a l f a c t o r s . F o r ex a m p l e , an a l y s i s of co n s t r u c t i o n a l m o r p h o l o g y of r e g u l a r Up p e r J u r a s s i c ec h i n o i d s pa r t i c u l a r l y al l o w s f o r t h e i n t e r p r e t a t i o n of wa t e r en e r g y , o x y g e n a v a i l a b i l i t y , a n d w a t e r d e p t h ( F i g . 7 ) ( B a u m e i s t e r , 1 9 9 7 ; Ba u m e i s t e r a n d L e i n f e l d e r , 19 9 8 ) .

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FIGURE 7. Analysis of constructional morphology of Jurassic regular echinoids for environmental interpretation. The three chosen examples represent a well-adapted and specialized deep-water form (R. rhodani), a largely ubiquitous. poorly specialized form of moderate water depth (D. gigantea), and a specialized shallow-water high-energy taxon (A. nobilis). (Data from Baumeister, 1997, and Baumeister and Leinfelder, 1998.)

(Note Figure is originally in landscape format, it was turned here 90° for better readability of this online-copy)

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T h i c k n e s s of t h e t e s t of a r e g u l a r ec h i n o i d i s a f i r s t i n d i c a t o r of wa t e r e n e r g y . Ju r a s s i c A c r o p o r a n o b i l i s , f o r e x a m p l e , h a s a v e r y t h i c k t e s t si m i l a r t o m o d e r n C o l o b o c e n t r o t u s a t r a t u s . S i m i l a r l y , A . n o b i l i s a l s o e x h i b i t s sa d d l e t y p e b r o a d e n e d sh o r t sp i n e s se r v i n g a s a p a r t i a l se c o n d a r y t e s t . A n o t h e r g o o d e n v i r o n m e n t a l i n d i c a t o r i s t h e m o r p h o l o g y o f o r a l sp i n e m a m m i l l a e . A t t a c h m e n t su r f a c e s a l l o w i n t e r p r e t a t i o n o f m o t i l i t y a n d st r e n g t h o f sp i n e s , a n d h e n c e a r e i n d i c a t i v e o f su b s t r a t e c h a r a c t e r i s t i c s . P r o b a b l y t h e b e s t e n v i r o n m e n t a l c r i t e r i a , h o w e v e r , a r e t h e a m b u l a c r a l p o r e sy s t e m s o f Ju r a s s i c r e e f ec h i n o i d s . An en o r m o u s nu m b e r of or a l P 3 / 4 - t y p e po r e s , wh i c h r e l a t e t o s t r o n g m u s c u l a r a m b u l a c r a l su c k e r f e e t , i n d i c a t e t h e a b i l i t y o f t h e t a x o n t o w i t h s t a n d h i g h w a t e r e n e r g y , a n d h e n c e a r e h i g h l y i n d i c a t i v e o f v e r y sh a l l o w , h i g h - e n e r g y r e e f s . S u c h f o r m s m a y be ac c o m p a n i e d by ec h i n o i d s wi t h a s l i g h t l y l o w e r r e s i s t i v i t y t o w a r d w a t e r e n e r g y ( P 2 / 3 i s o p o r e su c k e r d i s k ) t h a t l i v e d i n m o r e p r o t e c t e d a r e a s w i t h i n t h e r e e f s a n d so f o r t h . H o w e v e r , i t i s t h e f o r m wi t h th e hi g h e s t po t e n t i a l re s i s t a n c e th a t ch a r a c t e r i z e s th e e ne r g y se t t i n g . A n o t h e r i n t e r e s t i n g f e a t u r e i s r e g u l a r e c h i n o i d s w h i c h sh o w a n i n c r e a s e o f a m b u l a c r a l po r e r o w s wi t h P 1 i s o p o r e s r e l a t e d t o no n s u c k i n g am b u l a c r a l f e e t o r f o r m s su c h a s R h a b d o c i d a r i s rh o d a n i , a t a x o n t h a t e x h i b i t s sl i t l i k e C1 i s o p o r e s ac r o s s i t s en t i r e t e s t . C1 i s o p o r e s co r r e s p o n d t o f l a t t e n e d , b l a d e l i k e r e s p i r a t o r y a m b u l a c r a l f e e t . S u c h f o o t m o d i f i c a t i o n i s n o r m a l l y t y p ic a l o f t h e a b o r a l su r f a c e s o f i r r e g u l a r e c h i n o i d s , w h i c h b y t h e i r b u r r o w i n g l i f e h a b i t h a d t o i m p r o v e t h e i r r e s p i r a t o r y sy s t e m . T h e e p i b e n t h i c r e g u l a r R h a b d o c i d a r i s r h o d a n i e v o l v e d t h i s i n d e p e n d e n t l y an d t h e i n c r e a s e of no n m e c h a n i c a l a m b u l a c r a l P 1 f e e t i n t h e ot h e r ex a m p l e s al s o i s di a g n o s t i c of ei t h e r i n c r e a s e d a c t i v i t y or r e d u c e d ox y g e n av a i l a b i l i t y of t h e s e f o r m s . Ac t u a l l y , t h e la t t e r t y p e o c c u r i n si l i c e o u s sp o n g e r e e f s , a n d i n d e p e n d e n t e v i d e n c e sh o w s t h a t t h e s e r e e f s w e r e p o s i t i o n e d i n o u t e r r a m p se t t i n g s . R h a b d o c i d a r i s rh o d a n i a c t u a l l y l i v e d i n f a i r l y r e s t r i c t e d se t t i n g s a s r e f l e c t e d b y t h e l o w - d i v e r s i t y h o s t a s s o c i a t i o n ( s e e Se c t i o n 2. 4 . 4 ) . 2 . 3 . 4 . B i n d i n g a n d C e m e n t i n g O r g a n i s m s : K e e p i n g It A l l To g e t h e r B i n d i n g an d ce m e n t i n g or g a n i s m s ar e ex t r e m e l y i m p o r t a n t i n t h e r e e f e c o s y s t e m , si n c e t h e y f i x l o o s e su r p l u s m a t e r i a l t h a t c o u l d n o t b e st o r e d i n l o w e r r e e f ca v i ti e s or ex p o r t e d fr o m th e re e f . Mu c h of th e ma t e ri a l is pr o d u c e d b y b i o e r o s i o n , b u t t h e m o r e e x p o s e d t h e r e e f , t h e h i g h e r t h e p o r t i o n of a d d i t i o n a l d e b r i s g e n e r a t e d b y w a v e s a n d st o r m s . A s a c o n s e q u e n c e , h i g h e n e r g y r e e f s ne e d v e r y ef f e c t i v e bi n d i n g an d ce m e n t i n g or g a n i s m s , s u c h as t h e m o d e r n en c r u s t i n g c o r a l l i n e re d al g a e . Ma n y ot h e r or g a n i s m s su c h as so f t c o r a l s , e n c r u s t i n g sp o n g e s , b r y o z o a n s , a n d m i c r o b i a l f i l m s h e l p st a b i l i z e t h e l o o s e m a t e r i a l , bu t i t wa s on l y af t e r t h e a d a p t a t i o n of co r a l l i n e r e d al g a e t o h i g h l y a b r a s i v e se t t i n g s t h a t r e e f s c o u l d i n h a b i t t h e h i g h - e n e r g y e n v i r o n m e n t ( s e e Se c t i o n 4) . C a l c a r e o u s r e d a l g a e d i d e x i s t i n Ju r a s s i c r e e f s , b u t t h e y d i d n o t p l ay i m p o r t a n t ro l e s in re e f st a b i l i z a t i o n , sa v e fo r ve r y fe w ex c e p t i o n s wh e r e s o l e n o p o r i d bi n d s t o n e s co v e r co r a l r e e f s ( N o s e , 19 9 5 ; H e l m , 19 9 7 ) . A di r e c t

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273

a n c e s t o r t o t h e co r a l l i n e al g a e , M a r i n e l l a l u g e o n i , a r o s e d u r i n g t h e L a t e J u r a s s i c a n d a l s o i n h a b i t e d c o r a l r e e f s s p o r a d i c a l l y , b u t a g a i n w a s of n o i m p o r t a n c e f o r r e e f st a b i l i z a t i o n ( L e i n f e l d e r a n d W e r n e r , 1 9 9 3 ) . T h e m o s t i m p o r t a n t st a b i l i z a t i o n i n Ju r a s s i c r e e f s w e r e m i c r o b i a l f i l m s a n d m a t s , w h i c h c a l c i f i e d a s t y p i c a l m i c r o b o l i t e c r u s t f a b r i c s ( L e i n f e l d e r e t a l . , 1 9 9 3 b ) . Mi c r o b i a l ca l c i f i c a t i o n , r e s u l t i n g i n co m p a r a b l e t y p e s , al s o i s i m p o r t a n t in mo d e r n r e e f s , bu t i s l a r g e l y r e s t r i c t e d t o t h e ca v i t y an d ca v e en v i r o n m e n t s , pr o b a b l y b e c a u s e o f co m p e t i t i o n w i t h co r a l l i n e al g a e ( R e i t n e r , 1 9 9 3 ; Re i t n e r e t a l . , 1 9 9 6 ; M o n t a g g i o n i a n d Ca m o i n , 1 9 9 3 ) . 2 . 3 . 4 a . J u r a s s i c R e e f a l M i c r o b o l i t e s . J u r a s s i c , a n d si m i l a r l y o t h e r , m i c r o b o l i t e s sh o u l d b e c a t e g o r i z e d u n d e r a m a c r o s c o p i c , m e s o s c o p i c , a n d m i c r o s c o p i c s c a l e ( S c h m i d , 1 9 9 6 ) . A c o m b i n a t i o n o f t h e s e a l l o w s n o t on l y f o r a st r a i g h t f o r w a r d d e s c r i p t i v e c l a s s i f i c a t i o n b u t a l s o f o r g e n e t i c c l u e s ( S c h m i d , 1 9 9 6 ; L e i n f e l d e r e t al . , 1 9 9 6 ) ( F i g . 8) . T h e o c c u r r e n c e o f Ju r a s s i c m i c r o b o l i t e s w i t h si m i l a r t h r o m b o l i t i c fa b r i c s a t d i f f e r e n t w a t e r d e p t h s , i n c l u d i n g d e e p s h e l f se t t i n g s p r o b a b l y a b o u t 4 0 0 m

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d e e p ( J a n s a e t al . , 1 9 8 9 ; D r o m a r t e t al . , 1 9 9 4 ) a s we l l as t h e i r f r e q u e n t an d p r o l i f i c d e v e l o p m e n t i n Ju r a s s i c r e e f c a v e s ( S c h m i d , 1 9 9 5 ) , sh o w s t h a t m i c r o b o l i t e s w e r e p o t e n t i a l l y a p h o t i c , a n d h e n c e a r e n o t r e l a t e d so l e l y t o c y a n o b a c t e r i a l or i g i n . T h i s do e s no t ne c e s s a r i l y m e a n t h a t cy a n o b a c t e r i a l we r e n o t i n v o l v e d ; t h e y m a y e v e n h a v e d o m i n a t e d i n sh a l l o w s e t t i n g s . T h e c o n c l u s i o n i s t h a t m i c r o b i a l f i l m s an d m a t s co m p o s e d of cy a n o b a c t e r i a an d / o r e u b a c t e r i a , p o s s i b l y e v e n d i a t o m s , c a n r e s u l t i n t h e sa m e t y p i c a l c l o t t e d p e l o i d a l mi c r o f a b r i c th a t tr i g g e r s a th r o m b o l i t i c me s o f a b r i c . Su c h m i c r o b e s o f t e n p r o d u c e si m i l a r p o l y s a c c a r o i d m a c r o m o l e c u l e s t h a t f i x c a l c i u m i o n s a n d a c t as an or g a n i c c a t a l y s t f o r ca l c i f i c a t i o n ( R e i t n e r , 19 9 3 ) . T h r o m b o l i t i c t y p e s a r e f r e q u e n t f r o m sh a l l o w t o d e e p w a t e r , w h e r e a s s t r o m a t o l i t i c t y p e s a r e l a r g e l y t h o u g h n o t e x c l u s i v e l y r e l a t e d t o s h a l l o w w a t e r , p r o b a b l y b ec a u s e d i u r n a l ch a n g e s of l i g h t i n t e n s i t i e s ar e r e f l e c t e d by a do m i n a n c e o f m o t i l e o s c i l l a t o r i a n cy a n o b a c t e r i a. I f oc c u r r i n g i n de e p e r wat e r , ot h e r r e g u l a r ch a n g e s s u c h a s b a c k g r o u n d se d i m e n t a t i o n o r n u t r i e n t a v a i l a b i l i t y m i g h t h a v e c a u s e d a s i m i l a r t h o u g h l e s s p r o n o u n c e d l a m i n a t e d f a b r i c ( L e i n f e l d e r an d S c h mi d , 2000). R e d u c e d se d i m e n t a t i o n i s t h e m o s t i m p o r t a n t p r e r e q u i s i t e f o r t h e d e v e l o p m e n t o f m i c r o b i a l c r u s t s . Mi c r o b i a l f i l m s a l s o m a y g r o w u n d e r e l e v a t e d b a c k g r o u n d se d i m e n t a t i o n bu t th e n tr a p an d ba f f l e se d i m e n t ra t h e r t h an ca l c i f y i n t h e t y p i c a l cl o t t e d pe l o i d a l f a s h i o n ( F i g . 9) . T h i s pr o c e s s i s o b v i o u s by t h e d e v e l o p m e n t of l a m i n o i d a l f e n e s t r a l i n t e r t i d a l f a b r i c s ( l o f e r i t e s ) , wh i c h al s o w e r e f r e q u e n t d u r i n g t h e Ju r a s s i c . A n e x a m p l e i s t h e c o r a l r e e f - r i m m e d K i m m e r i d g i a n O t a P l a t f o r m o f c e n t r a l P o r t u g a l , w h e r e su c h l o f e r i t e s d e v e l o p e d va s t l y in ba c k r e e f po s i t i o n ( L e i n f e l d e r , 19 9 2 , 19 9 4 b ) . L o f e r i t e s ma y be p u r e ca r b o n a t e mu d s t o n e s or ev e n in t r a c l a s t i c gr a i n s t o n e s , an d t h e fr e q u e n t o c c u r r e n c e o f mi c r o b i a l ma t s is on l y in d i c a t e d b y la m i n o i d a l f e n e s t r a l f a b r i c s . I n o t h e r se t t i n g s w i t h si m i l a r b a c k g r o u n d s e d i m e n t a t i o n b u t g r e a t e r w a t e r d e p t h t h e oc c u r r e n c e of m i c r o b i a l m a t s wo u l d no t be do c u m e n t e d at a l l b e c a u s e di a g e n e s i s wo u l d be to o sl o w t o , , s h o c k fr o s t ì l a m i n o i d a l l y ar r a n g e d g a s bu b b l e s of de c a y i n g m i c r o b i a l m a t e r i a l ( L e i n f e l d e r an d Ke u p p , 1 9 9 5 ) . As a c o n c l u s i o n , t h e o c c u r r e n c e o f d i s t i n c t m i c r o b o l i t e f a b r i c s su c h a s t h r o m b o l i t e s o r st r o m a t o l i t e s w i t h a c l o t t e d p e l o i d a l m i c r o f a b r i c i s d i a g n o s t i c o f l o w se d i m e n t a t i o n r a t e s , a f a c t t h a t i s c o r r o b o r a t e d b y t h e f r e q u e n t o c c u r r e n c e o f m i c r o b o l i t e s a t h i a t u s e s a n d c o n d e n s a t i o n l e v e l s . H o w ev e r , s e d i m e n t a t i o n r a t e s ca n va r y , a n d gi v e n t h a t t h e y ar e b e l o w a cr i t i c a l t h r e s h o l d , m i c r o b i a l f a b r i c s r e f l e c t t h e s e ch a n g e s . Ar b o r e s c e n t , di g i t a t e m i c r o b i a l m e s o f a b r i c s i n d i c a t e e l e v a t e d ( b u t st i l l f a i r l y l o w ) b a c k g r o u n d s e d i m e n t a t i o n r a t e s . Co n s e q u e n t l y , o c c u r r e n c e an d f a b r i c p a t t e r n s o f m i c r o b o l i t e c r u s t s a r e a u s e f u l t o o l f o r se q u e n c e st r a t i g r a p h i c i n t e r p r e t a t i o n ( L e i n f e l d e r , 1 9 9 3 b ; N o s e , 1 9 9 5 ; se e S e c t i o n 2 . 4 . 2 ) . K e m p e ( 1 9 9 0 ) , Ke m p e an d Ka z m i e r c z a k ( 1 9 9 4 ) , an d Ke m p e e t al . ( 1 9 9 6 ) a r g u e d th a t va s t de v e l o p m e n t of mi c r o b o l i t e s du r i n g E a r t h hi s t o r y s ho u l d be i n d i c a t i v e o f st r o n g l y i n c r e a s e d se a w a t e r a l k a l i n i t y , w h i c h i n t u r n m a y b e a s s o c i a t e d wi t h ec o s y s t e m co l l a p s e s an d m a s s ap p e a r a n c e s of ca l c a r e o u s m i c r o b o l i t e s . Du r i n g th e Pr e c a m b r i a n , th i s wa s th o u g h t to be du e to th e so d i c n a t u r e of t h e oc e a n s , wh e r e a s d u r i n g t h e P h a n e r o z o i c al k a l i n i t y co u l d be

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fine, muddy particles settling from water column epifauna, e.g. sponges active microbial mat microbial mat (mostly with trichomal microbes) baffling particles

position of former unpreservable mat partial stabilisation of sediment by non-calcifying microbial mats

former mat not preserved by distinct texture dense micritic or micropeloidal sediment

allochthonous background sedimentation microbial mat baffles sediment particles -> no clear textural difference between former mat and mud

no particles settling from water column epifauna, e.g. sponges active microbial mat

coccoidal microbial mat, producing EPS start of carbonate precipitation within EPS fully calcified former EPS, resulting in microbolite crusts with distinct features (mostly thrombolitic)

microbolite crusts

stabilisation of sediment by calcifying microbial mats

dense micritic or micropeloidal sediment layers from sedimentation intervals

no allochthonous background sedimentation microbial mat precipitates carbonate within exopolymeric substances (EPS) --> clear textural difference between former mat and mud

FIGURE 9. Preservation of Jurassic microbial mats. Mats may grow with or without background sedimentation. Under slow sedimentation, mat microbes were probably dominated by trichomal cyanobacteria-trapping sediment particles. Distinct microbolite structures did not develop. Under strongly reduced to zero sedimentation microbes produced large amounts of exopolymeric substances (EPS), which largely are polysaccharoids and some proteins. EPS may act as catalyst for calcification in distinct, mostly thrombolitic, microbolite patterns.

(Note Figure is originally in landscape format, it was turned here 90° for better readability of this online-copy)

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regionally increased by stagnant basins via the H2S alkalinity pump or by increased influx of sialic weathering products. Probably Jurassic seas had a slightly higher alkalinity than today, which might have facilitated the formation of microbolite precipitation. However, the alkalinity model alone cannot explain the co-occurrence of pure thrombolite reefs and macrofauna-rich reefs at certain time intervals (see Section 2.4.4). Microbolites also occur as a typical element of Jurassic coral reefs, ranging presumably from oligotrophic to mesotrophic, so in general, microbolite development was largely eurytrophic. However, it appears plausible and there are several supporting arguments that microbolite development was enhanced whenever nutrient levels increased. In eastern Spain, a unique but widespread Oxfordian low-diversity association of hexactinosan sponges thrived under zero background sedimentation in a very oligotrophic setting, which was possible by the adaptations discussed earlier (see Section 2.3.2). Normally, the very reduced sedimentation rate should be favorable for extensive development of microbolites. However, in this special case, nutrient values were apparently so low that they only allowed for impoverished development of microbolites, making this example an exception to the reliability of microbolites that characteristically occur whenever sedimentation rates are very low. Another argument for the positive influence of nutrients on microbolite development is that reefal microbolite crusts are often better developed in areas with very reduced though noticeable terrigeneous influx relative to pure carbonate settings. Finally, the exclusion of reefal macrofauna for distinct time intervals in certain areas probably is often due to strong eutrophication that excluded the reef organisms. However, this can only be proven in cases where oxygen impoverishment occurred, which is highlighted by an association of pure microbolite reefs, bacterial framboidal pyrite, richness in authigenic glauconite, and the occurrence of dysaerobic or poikiloaerobic pectinid bivalves (Leinfelder, 1993a; Leinfelder et al., 1996). In principle, oxygen depletion might not necessarily be related to eutrophication but could be solely caused by lack of water exchange. Actually, slightly impoverished oxygenation under oligotrophic conditions is indicated by the before-mentioned sponge associations of eastern Spain, but as discussed earlier, vast microbolite development was not possible because of the lack of nutrients. In conclusion, pure microbolite development is interpreted here as directly indicative of eutrophication, which in some cases might even have resulted in discernable, occasional oxygen depletion. Black shales and bituminous sediments did not develop due to the lack of rapid burial from low sedimentation rates. This makes pure microbolite development perfect indicators of eutrophicationó oxygen depletion in low sedimentation regimes, at least for water depths where other limiting factors such as very high water energy or salinity fluctuations can be ruled out. Microbolites therefore are important tools for paleoceanographic reconstructions (see Section 2.4.4). 2.3.4b. Living on Microbolite Crusts. A wealth of other encrusting organ isms lived on the surfaces of Jurassic microbolite crusts. Many of these were

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bright / inner ramp Ø 700-1200 µm

moderately lit / middle ramp Ø 450-700 µm dim / outer ramp Ø < 450 µm

0m

dark / basin no outer test

50 m

100 m

150 m

FIGURE 10. Tubipliytes inorronensis, interpreted by Schmid (1995) as a miliolid foraminifer with a twofold test, occurs across a broad bathymetric range in Jurassic coral. sponge, and microbial reefs. The thickness of its outer test is correlated with illumination and can be used as a relative bathymetric dipstick, provided reef cave dwelling is recognized. (After Schmid, 1995, and Leinfelder et al., 1996, simplified.)

c o n s i d e r e d ea r l i e r as en i g m a t i c , al g a - t y p e or g a n i s m s , b u t ar e no w i n pa r t i n t e r p r e t e d as f o r a m i n i f e r s ( L e i n f e l d e r , 1 9 8 6 ; S c h m i d , 1 9 9 5 , 1 9 9 6 ; S c h m i d an d L e i n f e l d e r , 1 9 9 6 ) . S o m e o f t h e s e , s u c h a s t h e l o f t u s i i d fo r a m i n i f e r L i t h o c o d i u m a gg r eg a tu m , t he mi l io l id fo r am i ni f er T ub i ph y te s mo rr o ne n si s , o r the en i gm a ti c o r g a n i s m B a c i n e l l a ir r e g u l a r i s , i n s o m e c a s e s m a y a c t u a l l y c o n t r i b u t e t o b i n d i n g a n d c o n s t r u c t i o n o f r e e f s , w h e r e a s l i k e t h e o t h e r m i c r o e n c r u s t e r s (e . g . , t he en i gm a ti c K os c in o bu l li n a soc i al i s, b ry o zo a ns , se r p u l i d s ) th e y ar e no r m a l l y j u s t ac c e s s o r y or g a n i s m s . H o w e v e r , t h e y of t e n ar e pe r f e c t i n d i c a t o r s of en v i r o n m e n t a l f a c t o r s , pa r t i c u l a r l y wa t e r de p t h : L it h oc o di u m a nd B ac i ne l la b ot h a r e re s t r i c t e d t o s h a l l o w s e t t i n g s ; G i r v a n e l l a m i n u t a i s f r e q u e n t i n c o a s t a l s et t in g s; an d T ub i ph y te s , t ho u gh eu r yb a th i c, is ne v e r t h e l e s s a go o d in d i c a t o r ( F i g . 1 0 ) , s i n c e t h e t h i c k n e s s of i t s ou t e r wa l l ch a n g e s wi t h l i g h t av a i l a b i l i t y , a l t h o u g h l o w - l i g h t b u t sh a l l o w c a v e se t t i n g s m u s t b e t a k e n i n t o c o n s i d e r a t i o n ( S c h m i d , 19 9 6 ; L e i n f e l d e r an d S c h m i d , 20 0 0 ) . Us i n g m i c r o e n c r u s t e r a s s o c i a t i o n s r a t h e r t h a n i n d i c a t o r s p e c i e s , al l o w s f o r a ve r y r e f i n e d pa l e o b a t h y m e t r i c i n t e r p r e t a t i o n ( F i g . 11 ) . 2 . 3 . 5 . O t h e r O r g a n i s m s a n d In f r a s t r u c t u r e J o b s Sponges are assisted in water filtering by an enormous crowd of other o r g a n i s m s . H o w e v e r , it w o u l d b e b e y o n d t h e s c o p e o f th i s c h a p t e r t o di s c u s s t h e m a l l . Am o n g t h e m o s t c o m m o n ar e pe c t i n i d , os t r a c e a n , a n d p t e r i a c e a n b i v a l v e s , s e r p u l i d s , cr i n o i d s , br y o z o a n s , a n d b r a c h i o p o ds . De e p e r s p o n g e mo u n d s a l s o m i g h t c o n t a i n b u r r o w i n g b i v a l v e s , i n c l u d i n g r a r e n u c u l i d s an d pholadomyids, Pparts of which were sediment feeders.

Trancoso

M. do Casal Novo, Tavira

S. Isabel

Frias, Cotovio

- 30 m - 60 m - 90 m

CORALS Microsolena Trocharea Tricycloseris Psammogyra Amphiastrea Trochocyathus Caryophyllia

Actinastrea 'Lithophaga'-Ass. Microsolena Trocharea-Ass. low sedimentation typical morphotype changes

Microsolena

moderate sedimentation Microsolena, Thamnasteria

SPONGES coralline sponges and Calcarea

Diversity and abundance of major groups

siliceous sponges

‚Lithistid‘ demosponges Hexactinosa Lychniscosa

BIVALVES cementing bivalves

Praeexogyra pustulosa

abundance of 'lithophagid‘ bivalves

Atreta

REGULAR SEA-URCHINS with oral P4/3 sucker disks with increase of P1/2 isopores across entire test with conjugate slit-pores across entire test

MICROENCRUSTERS Bacinella Lithocodium-Ass. high-diversity association Girvanella-Ass. Terebella 'Tubipyhtes'- Ass. thickness of outer test of ‚Tubiphytes

FIGURE 11. Bathymetric distribution and comparative paleoecology of Upper Jurassic reef organisms and associatons from lberia. (Modified and expanded after Leinfelder et ei., 1993a,b, and Werner et al., 1994).

Ju ra ssi c Re e f Ec o sy ste m s

279

G a s t r o p o d s , i n c l u d i n g ne r i n e i d s , al s o ar e w i d e s p r e a d , b u t t h e i r l i f e ha b i t i s l a r g e l y u n k n o w n . Be l e m n i t e an d am m o n o i d t a x a , b e l o n g i n g t o t h e p r e d at o r s a n d p o s s i b l y sc a v e n g e r s , w e r e f r e q u e n t i n s p o n g e r e e f s a n d se v e r a l t a x a d e f i n i t e l y l i v e d w i t h i n t h e r e e f s . Cr u s t a c e a n s , m a n y o f w h i c h b e l o n g t o t h e , , l i t t e r r e c y c l i n g br i g a d e ì , ce r t a i n l y we r e al s o f r e q u e n t i n Up p e r J u r a s s i c r e e f s y s t e m s bu t ar e r a r e l y pr e s e r v e d . A hi g h nu m b e r of t a x a , ho w e v e r , a r e kn o w n f r o m t h e S o l n h o f e n , N u s p l i n g e n , a n d o t h e r l i t h o g r a p h i c l i m e s t o n e s o f so u t h e r n G e r m a n y , w h i c h d e v e l o p e d i n c l o s e a s s o c i a t i o n w i t h U p p e r Ju r a s s i c c o r a l a n d s p o n g e r e e f s . A m o n g t h e v e r t e b r a t e s a r e sp e c t a c u l a r l y p r e s e r v e d o r g a n i s m s o f U p p e r J u r a s s i c r e e f e c o s y s t e m s , su c h a s , , p a r r o t - f i s h - l i k e ì c h o n d r o s t e a n G y r o d u s , w h i c h p r o b a b l y f e d o n v a l v e d b e n t h o s a n d c o r a l s , a s w e l l a s sh a r k s a n d ra y s , re p t i l e s , an d ev e n A r c h a e o p t e r y x , t h e fi r s t bi r d th a t li v e d on is l a n d in t h e U p p e r Ju r a s s i c c o r a l - se a s o f so u t h e r n G e r m a n y ( f o r r e c e n t f i n d i n g s , se e , e . g . , R ˆ p e r e t a l . , 1 9 9 6 ; R e n e s t o a n d V i o h l , 1 9 9 7 ; D i e t l e t a l . , 1 9 9 7 ) . Ma n y o f t h e s e o r g a n i s m s p r o v i d e a d d i t i o n a l c l u e s t o t h e sp e c i a l se t t i n g s o f J u r a s s i c e c o s y s t e m s . Ce m e n t i n g b i v a l v e t a x a ch a n g e a l o n g a wa t e r d e p t h g r a d i e n t ( W e r n e r e t a l . , 1 9 9 4 ) , b u r r o w i n g b i v a l v e s a l l o w f o r t h e r e c o g n i t i o n o f so f t m u d s w i t h i n r e e f sy s t e m s , c r i n o i d t y p e s m a y i n d i c a t e e n e r g y l e v e l s , a n d t h e g e n e r a l a b u n d a n c e o f f i l t e r f e e d e r s a n d se d i m e n t f e e d e r s g i v e s i n s i g h t i n t o t h e t r o p h i c si t u a t i o n . Co m p a r a t i v e p a l e o e c o l o g i c a l a n a l y s i s a l l o w s e v a l u a t i o n o f d i f f e r e n c e s i n t h e s e pa t t e r n s . I t i s ve r y o b v i o u s , f o r ex a m p l e , t h a t t h e ge n e r a l o c c u r r e n c e o f , , t r u e ì ( i . e . , n o n c y a n o b a c t e r i a l ) ca l c a r e o u s al g a e , su c h as d a s y c l a d a c e a n s , o c c u r i n sh a l l o w - w a t e r c o r a l r e e f se t t i n g s r a t h e r t h a n i n s p o n g e r e e f s . Ad d i t i o n a l l y , ce r t a i n t a x a of da s y c l a d a c e a n s , f o r a m i n i f e r s , n e r i n e i d s , an d am m o n o i d s al l o w f o r pa l e o t e m p e r a t u r e an a l y s i s , bi o g e o g r a p h i c c o m p a r i s o n , or bi o s t r a t i g r a p h i c co r r e l a t i o n . 2 . 4 . Co n t r o l l i n g F a c t o r s of Ju r a s s i c Re e f E c o s y s t e m s : T h e Co m p a r a t i v e Ap p r o a c h A b o v e I h a v e d i s c u s s e d t h e r o l e o f Ju r a s s i c o r g a n i s m s i n t h e r e e f e c o s y s t e m a n d h i g h l i g h t e d so m e e x a m p l e s w h e r e f u n c t i o n a l a u t e c o l o g i c a l i n t e r p r e t a t i o n a n d ge n e r a l co n s i d e r a t i o n s ab o u t th e bi o l o g y of re e f or g a n i s m s gi v e cl u e s to m a n y en v i r o n m e n t a l pa r a m e t e r s . T h i s kn o w l e d g e i s i m p o r t a n t wh e n i n t e r p r e t i n g qu a l i t a t i v e an d qu a n t i t a t i v e p a t t e r n s of c o - o c c u r r e n c e of or g a n i s m s . M o d e r n r e e f se t t i n g s a r e b e s t c h a r a c t e r i z e d b y d i a g n o s t i c r e e f a s s o c i a t i o n s t h a t pa r t i c u l a r l y r e f l e c t wa t e r de p t h an d en e r g y l e v e l s bu t al s o ot h e r f a c t o r s su c h a s n u t r i e n t a v a i l a b i l i t y o r se d i m e n t a t i o n r a t e . T h i s a p p r o a c h i s p a r t i c u l a r l y us e f u l in th e At l a n t i c ó C a r i b b e a n r e a l m wh e r e ge n e r a l r e e f di v e r s i t y is lo w e r th a n in th e In d o p a c i f i c and d o m i n a n c e of ce r t a i n ta x a und e r gi v e n e n v i r o n m e n t a l pa r a m e t e r s i s ob v i o u s . E x a m p l e s of us e f u l r e e f as s o c i a t i o n s ar e t h e A c r o p o r a p a l m a t a a s s o c i a t i o n , th e M o n t a s t r e a a n n u l a r i s a s s o c i a t i o n , th e P or i te s po ri t es a ss o ci a ti o n, or th e A . cer v ic o rn i s a ss o ci a ti o n, am o ng ma n y o th e r s (e.g., Geister, 1983, 1992; Greb et al., 1996), all of which reflect d if f er e nt e ne r gy le v el s an d wat e r dep t hs . Sl ig h tl y el ev a te d ba ck g ro u nd se d im e nt a ti o n

280

Ch a p te r 8

r a t e s c a n be r e f l e c t e d i n di f f e r e n t r a t i o s of ke y t a x a ab u n d a n c e , s u c h as M o n t a s t r e a ca v e r n o s a v e r s u s M o n t a s t r e a an n u l a r i s ( G r e b e t a l . , 1 9 9 6 ) , or i n t h e o c c u r r e n c e o f r o b u s t a s s o c i a t i o n s a s , f o r i n s t a n c e , i n t h e st r o n g l y t e r r i g e n e o u s l y i n f l u e n c e d r e e f s o f f Br a z i l ( L e „ o an d Gi n s b u r g , 1 9 9 7 ) . A l t h o u g h r e e f as s o c i a t i o n s m a y ap p e a r al r e a d y di s t i n c t i n a qu a l i t a ti v e m a n n e r , i t i s pa r t i c u l a r l y i m p o r t a n t t o us e qu a n t i t a t i v e or at l e a s t s e m i q u a n t i t a t i v e cr i t e r i a on ab u n d a n c e of t a x a ( w h e n e v e r po s s i b l e a t t h e s p e c i e s l e v e l ) i n o r d e r t o de c i p h e r en v i r o n m e n t a l pa r a m e t e r s i n a r e l i a b l e f a s h i o n . A l o t o f q u a n t i t a t i v e a n d se m i q u a n t i t a t i v e f a u n a l a n d f l o r a l a n a l y s e s o f m a n y U p p e r Ju r a s s i c r e e f s a r e n o w a v a i l a b l e , b e s i d e s n e w q u a l i t a t i v e d a t a o n re e f fa u n a s , wi t h po s s i b l y t h e be s t ex a m p l e s fr o m Po r t u g u e s e an d Sp a n i s h c o r a l r e e f s ( E r r e n s t , 1 9 9 0 a , b ; Ro s e n d a h l , 1 9 8 5 ; L e i n f e l d e r , 1 9 8 6 , 1 99 4 b ; N o s e , 1 9 9 5 ; S c h m i d , 1 9 9 6 ; Au r e l l an d B· d e n a s , 1 9 9 7 ; No s e an d L e i n f e l d e r , 1 9 9 7 ) . A v e r y u s e f u l m e t h o d f o r c o m p a r a t i v e st u d i e s i s t h e e s t a b l i s h m e n t o f c o r a l f a u n a di v e r s i t i e s ba s e d o n t h e , , t r o p h i c nu c l e u s ì co n c e p t an d t h e S h a n n o n I n d e x ( K a u f f m a n an d S c o t t , 19 7 6 ; Od u m , 19 8 3 ; We r n e r , 19 8 6 ) . T h e t r o p h i c n u c l e u s i s c o m p o s e d o f t h e m i n i m u m n u m b e r o f sp e c i e s w h o s e i n d i v i d u a l s am o u n t t o at l e a s t 8 0 % o f t h e e n t i r e i n d i v i d u a l n u m b e r . It i s p l a u s i b l e t o u s e v o l u m e p e r c e n t ( w h i c h ca n b e d o n e b y i m a g e an a l y s i s or by a p p l y i n g v o l u m e f a c t o r s t o p e r c e n t a g e s b a s e d o n n u m b e r s o f i n d i v i d u al s ) . G o o d t a x o n o m i c d a t a o n t h e sp e c i e s l e v e l a l s o a r e a v a i l a b l e f r o m n o r t h e r n G e r m a n y (B e r t l i n g , 19 9 3 ) . Ma n y ne w da t a al s o ar e av a i l a b l e fr o m th e Lor r a i n e a n d S w i s s co r a l r e e f s ( I n s a l a c o , 19 9 6 a ; I n s a l a c o e t al . , 1 9 9 7 ) , bu t t a x o n o m i c r e s o l u t i o n m o s t l y i s o n l y o n t h e g e n e r i c l e v e l , e x c e p t f o r a f e w st u d i e s ( G e i s t e r an d L a t h u i l i È r e , 1 9 9 1 ; B. L a t h u i l i È r e , p e r s o n a l co m m u n i c a t i o n ; L a t e r n s e r , 2 0 0 0 ) . A s f o r t h e si l i c e o u s sp o n g e f a c i e s , t h e I b e r i a n U p p e r J u r a s s i c e x a m p l e s ar e we l l s t u d i e d ( L e i n f e l d e r e t al . , 1 9 9 3 a ; We r n e r e t al . , 1 9 9 4 ; K r a u t t e r , 1 9 9 5 , 1 9 9 7 ; M . K r a u t t e r , p e r s o n a l c o m m u n i c a t i o n ) d o w n t o th e s p e c i e s l e v e l , a n d m a n y n e w r e s u l t s o n sp o n g e r e e f s a r e a v a i l a b l e f r o m t h e F r e n c h , S w i s s , G e r m a n , P o l i s h , a n d Ru m a n i a n Ju r a s s i c ( G a i l l a r d , 1 9 8 3 ; H e r r m a n n , 1 9 9 6 ; Ma t y s z k i e w i c z , 1 9 9 6 , 1 9 9 7 ; K e u p p e t a l . , 1 9 9 6 ; K o c h , 1 9 9 6 ; K o c h e t a l . , 1 9 9 4 ; P i s e r a , 1 9 9 7 ) , a l t h o u g h d i s t i n c t sp o n g e a s s o c i a t i o n s b a s e d o n r e p r e s e n t a t i v e p o p u l a t i o n s c o u l d on l y be es t a b l i s h e d oc c a s i o n a l l y ( W e r n e r e t al . , 1 9 9 4 ; K r a u t t e r , 19 9 5 , 19 9 7 ) . 2 . 4 . 1 . P a l e o e c o l o g i c a l G r a d i e n t s a n d T h e i r In t e r p l a y Leinfelder (1993a) and Leinfelder et al. (1993a,b) recognized the strong control of physical environmental parameters on the establishment and composition of Upper Jurassic reefs based on paleoecological, sedimentological, and sequential analysis. They stated that water depth, sedimentation rate, and nutrient-oxygen fluctuations were the dominant controlling mechanisms besides water energy, temperature, substrate, and salinity. They demonstrated (Fig. 12) that reef growth is only possible if background sedimentation drops below a critical threshold, allowing for improvement in diversity and formation of microbial crusts when substantially lowered. This is true for shallow water and deeper shelf reef types, which change along the bathymetrical

281

increasing frequency of oxygen fluctuations

increasing frequency of nutrient fluctuations

Ju ra ssi c Re e f Ec o sy ste m s

a) Late Jurassic pure microbolite

- O2 + O2

coral-siliceous sponge microbolites coral microbolites

coral framestones, coral-microbial crust-debris reefs

siliceous sponge-bearing microbolite

siliceous sponge meadows siliceous spongemicrobolite mudmounds

in se cr di ea m si en ng ta tio n

ra te

high-diversity coral meadows

coral meadows rich in siliceous sponges low-diversity coral meadows, coral-debris-reefs*

increasing water depth

coral-siliceous sponge reefs

siliceous sponge meadows

- O2

deep-water coral mounds

+ O2

high-diversity coral-algal reefs

soft-coral and softsponge dominated reefs ? ?

n

ra

te

increasing frequency of nutrient fluctuations

b) Modern

di m

en ta

tio

Halimeda mounds

?

increasing water depth

se

low-diversity coral reefs oyster reefs

in c

re

as

in g

?

FIGURE 12. (a) The triple factor model of Upper Jurassic reefs in Comparison with (b) a similar tentative model for modern reefs. Differences in background sedimentation rate, bathymetry, nutrients, and oxygen concentrations largely determines the occurrence and composition of Jurassic reefs. Environmental tolerances are much smaller in modern reefs. Note that modern deepwater coral mounds show an offset distribution, appearing in a separate ,reef windowì (cf. 20). See text for further explanation. (Modified after Leinfelder, 1993a, Leinfelder et al., 1996, and Leinfelder and Nose, 1999.).

282

Ch a p te r 8

g r a d i e n t f r o m c o r a l a s s o c i a t i o n s t o m i x e d c o r a l - s i l i c e o u s sp o n g e t o p u r e s i l i c e o u s sp o n g e a s s o c i a t i o n s . Ba t h y m e t r y b y i t s e l f i s n o si n g l e f a c t o r , b u t r e l a t e s t o a v a r i e t y o f f a c t o r s su c h a s i l l u m i n a t i o n , a b u n d a n c e o f p l a n k t o n , t e m p e r a t u r e , an d at m o s p h e r i c pr e s s u r e . S e d i m e n t a t i o n r a t e no t on l y m o d e r a t e s d i v e r s i t y , bu t al s o t h e de v e l o p m e n t of m u d m o u n d s , wh i c h ne e d a r e d u c e d bu t n o t i c e a b l e b a c k g r o u n d se d i m e n t a t i o n r a t e f o r t h e i r d e v e l o p m e n t . R e s e d i m e n t a t i o n a l s o i s t h e c r i t i c a l f a c t o r i n h i g h - e n e r g y se t t i n g s , p r e v e n t i n g m i c r o b o l i t e de v e l o p m e n t un l e s s t h e ph y s i c a l l y ge n e r a t e d de b r i s m a t e r i a l ca n b e e x p o r t e d a n d i n t e r n a l se d i m e n t a t i o n a n d r e s e d i m e n t a t i o n i s r e d u c ed . O n e U p p e r J u r a s s i c c o r a l a s s o c i a t i o n w a s e v e n a d a p t e d t o r e d u c e d sa l i n i t i e s , w h e r e a s th e r e s t wa s f u l l y ma r i n e ( L e i n f e l d e r e t al . , 1 9 9 6 ) . A n o t h e r cr i t i c a l f a c t o r i s t h e co n c e n t r a t i o n of nu t r i e n t s , wh i c h of t e n is c o u p l e d w i t h t e r r i g e n e o u s b a c k g r o u n d se d i m e n t a t i o n . i t a p p e a r s t h a t e l e v a t e d o l i g o t r o p h i c c o n d i t i o n s c o u l d b e t o l e r a t e d o n l y b y sp e c i a l i z e d h e x a c t i n e l l i d s p o n g e s , w h e r e a s m o d e r a t e l y o l i g o t r o p h i c t o sl i g h t l y m e s o t r o p h i c c o n d i t i o n s w e r e t h e m o r e f a v o r a b l e se t t i n g s f o r m o s t J u r a s s i c r e e f s . I f n u t r i e n t c o n c e n t r a t i o n s w e r e st r o n g l y r a i s e d a n d e v e n t u a l l y e v e n a c c o m p a n i e d b y b o t t o m - w a t e r o x y g e n d e p l e t i o n , g r o w t h o f m a c r o f a u n a w a s p o s s i b l e o n l y d u r i n g t h e no r m a l e p i s o d e s , wh e r e a s m i c r o b o l i t e s co u l d de v e l o p i n ei t h e r s it u at i on . Depe n di n g on t he fr e qu e nc y of eu tr o ph i ca t io n -d y so x yg e na t io n pu ls e s, ma c ro f au n a was r es t ri c te d to di st i nc t le ve l s or eve n wa s exc l ud e d fro m re ef de v el o pm e nt , so it e v e n t u a l l y g a v e ri s e t o p u r e m i c r o b o l i t e r e e f s ( F i g . 1 2 ) . T h i s c o n c e p t w a s f ur t he r de ve l op e d and ap p li e d by Lei n fe l de r e t al. ( 19 9 4, 19 9 6) , No se (1 9 95 ) , S c h m i d (1 9 9 6 ) , a n d In s a l a c o e t a l . ( 1 9 9 7 ) . L e i n f e l d e r a n d N o s e ( 1 9 9 9 ) . c o m p ar e d ree f wi nd o ws an d ge ne r al en v ir o nm e nt a l gra d ie n ts fr o m Jur a ss i c and m o d e r n r e e f s , s t a t i n g th a t m o d e r n c o r a l r e e f g r o w t h h a s n a r r o w e r e n v i r o n m e n t a l t o l e r a n c e s t h a n Ju r a s s i c c o r a l r e e f s , o w i n g t o i n c r e a s i n g sp ec i a l i z a t i o n o f r e e f o r g a n i s m s a n d c o m p l e x i t y o f r e e f st r u c t u r e ( F i g . 1 2 ) . W a t e r d e p t h , se d i m e n t a t i o n r a t e , n u t r i e n t c o n c e n t r a t i o n s , a n d o x y g e n v a l u e s t h e m s e l v e s a r e st r o n g l y g o v e r n e d b y se a - l e v e l st a t e a n d g e o t e c t o n i c s t r u c t u r e . T h e r e f o r e , t h e a c t u a l p o s i t i o n o f a g i v e n r e e f w i t h i n t h e se g r a d i e n t s e v e n t u a l l y r e f l e c t s th e ge o t e c t o n i c , pa l e o g e o g r a p h i c , a n d pa l e o c e a n o g r a p h i c s e t t i n g , w h i c h m a k e s r e e f a n a l y s i s a p o w e r f u l t o o l t o d e c i p h e r t h e Ju r a s s i c r e g i o n a l a n d g l o b a l e c o l o g y a s w e l l a s a n d g e o t e c t o n i c a n d se q u e n t i a l d e v e l o p m e n t ( L e i n f e l d e r , 19 9 4 a ) . 2 . 4 . 2 . C o n t r o l o f Ec o l o g i c a l G r a d i e n t s b y S e a - L e v e l F l u c t u a t i o n s A g e n e r a l se q u e n c e st r a t i g r a p h i c m o d e l h a s b e e n d e v e l o p e d f o r Ju r a s s i c r e e f s i n f l u e n c e d b y t e r r i g e n e o u s i n p u t ( F i g . 1 3 ) . Re e f g r o w t h g e n e r a l l y o c c u r r e d i n t h e co m p a n y of t h i r d - o r d e r s e a - l e v e l r i s e s t h a t wi d e l y r e d u c e d t h e t e r r i g e n e o u s i n f l u x a c r o s s t h e sh e l f . I n d e p e n d e n t a n a l y s i s o f g r o w t h r a t e s f o r r e e f s , ba s e d on co r a l an d m i c r o b o l i t e gr o w t h r a t e s ( S c h m i d , 19 9 6 ) , ho w e v e r , r e v e a l e d t h a t m o s t I b e r i a n r e e f s di d no t gr o w ac r o s s an en t i r e t r a n s g r e s s i v e t h i r d - o r d e r cy c l e b u t oc c u r r e d on l y du r i n g ad d i t i o n a l e n v i r o n m e n t a l im p r o v e m e n t a l o n g w i t h f o u r t h - o r f i f t h - o r d e r se a - l e v e l r i s e t h a t e v e n t u a l l y o p e n e d t h e

283

Ju ra ssi c Re e f Ec o sy ste m highstand / early lowstand

elevated terrigenous influx

reef windows

CORAL REEF ZONE

NO REEFS sea level

oligospecific coral thickets (only sporadically) low-diversity coral debris reefs (constant winnowing)

4th/5th order - ? 50 m -

-O2 or eutrophication

low-diversity coral meadows (if terrigenous sediment is mostly bypassed)

elevated terrigenous sedimentation, no reefs

transgressive / early highstand

PURE MICROBOLITE ZONE

reef windows

SPONGE REEF ZONE MIXED

CORAL REEF ZONE

medium-diversity marly coral thickets

sea level medium div. coral debris reefs marly coral-microbolite reefs high-diversity coral-microbolite reefs

4th/5th order - ? 50 m -

medium to high-diversity deepwater coral reefs

-O2 or eutrophication

crust-rich mixed coral - siliceous sponge reefs siliceous sponge microbolite mudmounds amd biostromes pure microbolite reefs

major transgressive peak: partial collapse of circulation

normal reef window sea level

PURE MICROBOLITE REEF ZONE

4th/5th order - ? 30 - 50 m -

CORAL REEF ZONE

medium-diversity marly coral thickets

medium-div. coral debris reefs high-diversity coral-microbolite reefs repetitive successions of pure microbolites to coral-microbolite reefs

-O2 or eutrophication pure microbolites

FIGURE 13. Simplified sequence stratigraphic model for Upper Jurassic reefs in terrigeneously influenced settings. During highstand and early lowstand reefs, sedimentation is elevated across the shelf so that reefs may only occur in the constantly wave-washed zone, giving rise to the typical coral-debris reefs. Low-diversity marly coral meadows also may occur sporadically. During sea-level rise, reefs of various types expand widely across the shelf. Due to very reduced sedimentation, reefs often contain a high-diversity fauna and are rich in microbolite crusts, resulting in distinct reef bodies, commonly with pronounced relief. Sea-level rise, however, might also lead to a partial collapse of shelf circulation due to additional climatic equilibration, giving rise to atrophic or oxygen-depleted settings with pure microbolite reefs occurring up to fairly shallow waters. Most reefs grew only during fourth- and fifth-order floodings within a third-order framework.

284

Ch a p te r 8

, , r e e f wi n d o w ì ( F i g . 13 ) . L e i n f e l d e r ( 1 9 9 3 a ) an d L e i n f e l d e r e t a l . ( 1 9 9 4 ) p o i n t e d o u t t h a t i n a r e a s d i s t a n t t o si l i c i c l a s t i c h i n t e r l a n d , su c h a s t h e sp o n g e m u d m o u n d s o f s o u t h e r n G e r m a n y , g e n e r a l r e e f g r o w t h m a y p e r s i s t a c r o ss s e v e r a l t h i r d - o r d e r c y c l e s b u t d o e s sh o w l a t e r a l w a x i n g a n d w a n i n g c o r r e l a t a b l e w i t h se a - l e v e l f l u c t u a t i o n s . T h i s i l l u s t r a t e s t h a t v a r i a t i o n s o f b a c k g r o u n d s e d i m e n t a t i o n d u e t o se a - l e v e l o s c i l l a t i o n s d o h a v e p r o n o u n c e d a n d d e t e r m i n i ng ef f ec t s of ree f gr ow t h eve n in th es e ca se s , an exa m pl e of wh ic h is di s c u s s e d i n S e c t i o n 2 . 4 . 4 b . H i g h s t a n d a n d l o w s t a n d r e e f s a r e r a r e r a n d a r e e i th e r o f t h e c o n s t a n t l y w i n n o w e d h i g h - e n e r g y t y p e o r sh o w v e r y i m p o v e r i s h e d d i v e r s i t i e s (Fig. 13). 2 . 4 . 3 . Co n t r o l of E c o l o g i c a l Gr a d i e n t s b y S h e l f Co n f i g u r a t i o n S h e l f s t r u c t u r e n o t o n l y d e t e r m i n e s b a t h y m e t r y , b u t i n f l u e n c e s se d i m e n t a t i o n an d r e s e d i m e n t a t i o n i n a d d i t i o n t o s e a - l e v e l f l u c t u a t i o n s ( F i g . 14 ) . On l o w - a n g l e r a m p s , r e e f s o f t h e h i g h - e n e r g y z o n e h a v e p r o b l e m s ex p o r t in g t h e b i o l o g i c a l l y a n d w a v e - g e n e r a t e d d e b r i s t h a t c o n t i n u o u s l y r e s e d i m e n t s . Re e f s

FIGURE 14. Jurassic reef types differ according to different shelf configurations and positions. Some characteristic examples are given. Homoclinal ramps (foreground) show characteristic coralódebris reefs in agitated water and siliceous sponge mounds or biostromes in the lower mid to outer ramp. Steepened ramps and rimmed shelves may suppress sponge mound development in deeper waters because of proximity to mud and sand-exporting. shallow-water carbonate factories. Steepened depositional slopes are the preferred site for crust-rich reefs of moderately deep water, whereas coralómicrobolite--debris reefs are indicative of a position in dose proximity to a bypass margin. enabling enhanced gravitational export of surplus calciclastics generated within the reefs.

Ju ra ssi c Re e f Ec o sy ste m s

285

a r e t h e r e f o r e c r u s t - f r e e a n d s h o r t - l i v e d , s i n c e t h e y n o r m a l l y a r e s uf f o c a t e d i n t h e i r o w n de b r i s . S u c h r e e f s m u s t ha v e be e n am o n g t h e m o s t wi d e s p r e a d bu t a r e o f t e n o v e r l o o k e d si n c e t h e i r r e l i c s a r e t a k e n a s a l l o c h t h o n o u s r e e f d e b r i s o f ot h e r no n p r e s e r v e d r e e f s . L a r g e r e l i c s o f i s o l a t e d m a s s i v e co r a l s or ev e n r e l i c s of t h e or i g i n a l f r a m e w o r k ar e i n d i c a t i v e of t h e ex i s t e n c e of t h e r e e f s ( c o r a l ó d e b r i s r e e f t y p e ) . A go o d ex a m p l e of a pa r t i a l l y pr e s e r v e d r e e f ar e s o m e O x f o r d i a n r e e f s a t S t . U r s a n n e , S w i t z e r l a n d ( T a k a c s , u n p u b l i s h ed r e s u l t s ) o r m a n y r e e f s i n l b e r i a , su c h a s r e e f b o d i e s o f t h e A m a r a l f o r m a t i o n ( N o s e , 19 9 5 ) . I f a sl o p e b r e a k e x i s t e d , a l a r g e p r o p o r t i o n o f t h e d e b r i s c o u l d b e e x p o r t e d , g i v i n g r i s e t o t h e d e v e l o p m e n t o f c o r a l ó m i c r o b i a l ó d e b r i s re e f s . T h e s e w e r e r e e f s t h a t gr e w at s l o p e ed g e i n t h e co n s t a n t l y wa v e - w a s h e d zo n e , a n d he n c e ar e r i c h i n f r a g m e n t s of co r a l s a n d ot h e r r e e f or g a n i s m s . C o n t r a s t i n g t h e co r a l ó de b r i s o f hi g h - e n e r g y r a m p s , t h e s e r e e f s co n t a i n a l o t o f m i c r o b i a l c r u s t s , st a b i l i z i n g a n d c e m e n t i n g t h e l o o s e , w a v e - g e n e ra t e d m a t e r i a l . T h i s wa s on l y po s s i b l e du e t o f a c i l i t a t e d wi n n o w i n g an d g r a v i t a t i o n a l e x p o r t o v e r a st e e p d e p o s i t i o n a l o r b y p a s s m a r g i n so t h a t m i c r o b o l i t e c r u s t s c o u l d st a b i l i z e t h e r e m a i n i n g m a t e r i a l . A c a s e s t u d y f o r t h i s t y p e a r e t h e sh e l f - e d g e r e e f s o f t h e n a r r o w O t a p l a t f o r m o f c e n t r a l P o r t u g a l ( L e i n f e l d e r , 19 9 2 , 19 9 4 b ) , bu t co m p a r a bl e r e e f s oc c u r el s e w h e r e ( e . g . , S c h m i d a n d Jo n i s c h k e i t , 1 9 9 5 ) . E x p o r t o f se d i m e n t a c r o s s a st e e p e n e d sl o p e p r e v e n t e d t h e g r o w t h o f d e e p e r s h e l f s p o n g e r e e f s , a n d i t i s o n l y a t t h e s t e e p s l o p e s t h a t m i cr o b i a l c r u s t - r i c h r e e f s ma y ha v e de v e l o p e d du e to th e gi v e n by p a s s po s s i b i l i t i e s . C o n s e q u e n t l y , c o r a l - m i c r o b i a l r e e f s a n d c o r a l - s p o n g e - m i c r o b i a l r e ef s a r e c h a r a c t e r i s t i c o f v e r y r e d u c e d se d i m e n t i n f l u x , a n d a s su c h a r e o f t e n i n d i c a t i v e o f st e e p e n e d sl o p e s . T h e y m a y , h o w e v e r , a l s o o c c u r d u r i n g se a - l e v e l r i s e o n h o m o c l i n a l r a m p s be l o w t h e f a i r we a t h e r wa v e ba s e as a co n s e q u e n c e of r e d u c e d se d i m e n t a t i o n . I f o n a sl o p e se t t i n g , su c h r e e f s a r e a c c o m p a n i e d b y a l l o c h t h o n o u s se d i m e n t s , su c h a s t u r b i d i t e s a n d d e b r i t e s , o r c a n y o n d e v e l o p m e n t . W e l l - s t u d i e d e x a m p l e s o r i g i n a t e f r o m c e n t r a l a n d so u t h e r n P o r t u g a l a n d S p a i n ( L e i n f e l d e r e t a l . , 1 9 9 3 a ; No s e , 1 9 9 5 ; S c h m i d , 1 9 9 6 ; Ba u m g ‰ r t n e r an d R e y l e , 19 9 5 ) . T h e c o r a l - m i c r o b o l i t e - d e b r i s r e e f t y p e m e n t i o n e d ab o v e , h o w e v e r , i s a l w a y s d i a g n o s t i c f o r st e e p sl o p e s , e v e n w i t h o u t a d d i t i o n a l s e d i m e n t o l o g i c a l c r i t e r i a , su c h a s a l l o c h t h o n o u s se d i m e n t s . S i l i c e o u s sp o n g e m u d m o u n d s a r e l a r g e l y c o n f i n e d t o l o w e r m i d t o o u t e r , o f t e n h o m o c l i n a l , r a m p se t t i n g s t h a t a r e d i s t a n t f r o m s h a l l o w - w a t e r c a r b o n a t e f a c t o r i e s , b e c a u s e i n t h i s p o s i t i o n t h e y r e c e i v e su i t a b l e a m o u n t s o f a l l o c h t h o n o u s m u d d y m a t e r i a l f o r t h e i r g r o w t h . I n c a s e s w h e r e s h a l l o w - w a t er c a r b o n a t e f a c t o r i e s a r e l a c k i n g a n d t e r r i g e n e o u s s e d i m e n t a l s o i s n ot i m p o r t e d , n o m o u n d s ca n gr o w du e t o bo t h l a c k of al l o c h t h o n o u s m a t e r i a l an d s u p e r o l i g o t r o p h ic c o n d i t i o n s , t he la t t e r of wh i ch pr e v e n t s th e pe r v as i v e gr o w t h o f m i c r o b o l i t e s ( L e i n f e l d e r , 19 9 4 a ; L e i n f e l d e r e t al . , 1 9 9 6 ) . Un d e r th e s e c o n d i t i o n s , l o w - d i v e r s i t y sp o n g e b i o s t r o m e s w i t h e n o r m o u s i n d i v i d u a l n u m b e r s m a y d e v e l o p ( K r a u t t e r , 1 9 9 7 ; Se c t i o n 2 . 4 . 4 c ) . I f i n f l u x o f c a r b o n a t e m u d i s t o o h i g h f o r t h e g r o w t h o f sp o n g e m o u n d s , s p o n g e b i o s t r o m e s m a y st i l l d e v e l o p , wh i c h i n t h i s ca s e ar e m u d - r i c h an d of t e n co n t a i n l o w e r nu m b e r s an d d i f f e r e n t si l i c e o u s sp o n g e m o r p h t y p e s t h a n l o w - s e d i m e n t a t i o n b i o s t r o m e s . I f

286

Ch a p te r 8

c a r b o n a t e f a c t o r i e s w e r e t o o n e a r b e c a u s e o f st e e p sh e l f sl o p e s , n e i t h e r b i o s t r o m e s no r bi o h e r m s co u l d d e v e l o p . G i v e n s u i t a b l e c o n d i t i o n s , g r o w t h o f sp o n g e m o u n d s m a y b e p e r v a s i v e , s u c h a s o n t h e b r o a d s h e l f s e a o f so u t h e r n G e r m a n y . Mo u n d s h a v e t h e t e n d e n c y t o a m a l g a m a t e v e r t i c a l l y , a n d t h u s m a y c r e a t e st r o n g su b m a r i n e r e l i e f i f sp o n g e r e e f g r o w t h i s n o t i n t e r r u p t e d b y l o n g e r p e r i o d s o f s e d i m e n t a t i o n . D u r i n g t h e l a t e K i m m e r i d g i a n , m o u n d s w i t h su b m a r i n e r e l i e f o f mo r e th a n 50 m a r e kn o w n ( G w i n n e r , 19 7 6 ) . T h e s e ga v e r i s e to th e p u n c t u a t e d oc c u r r e n c e of co r a l re e f s on th e hi g h e s t mo u n d s . Mo s t of th e s e r e e f s a r e of t h e co r a l - d e b r i s t y p e an d t h e co r a l - m i c r o b o l i t e - d e b r i s t y p e ( u n p u b l i s h e d r e s u l t s , cf . P a u l s e n , 19 6 4 ) . I n t h i s ex a m p l e , t h e ho m o c l i n a l , n e a r l y l e v e l - b o t t o m i n i t i a l o u t e r r a m p c o n f i g u r a t i o n w a s su i t a b l e f o r e x t e n s i v e g r o w t h o f sp o n g e - m i c r o b i a l m u d m o u n d s f r o m t h e L a t e O x f o r d i a n o n w a r d , w h i c h i n t u r n c h a n g e d t h e c o n f i g u r a t i o n o f t h e sh e l f , a n d h e n c e t h e c o n t r o l l i n g f a c t o r s o f r e e f g r o w t h , su c h a s b a t h y m e t r y , w a t e r e n e r g y , a n d se d i m e n t a t i o n r e s e d i m e n t a t i o n pa t t e r n s . S i m i l a r , pa r t i a l l y i n t r i n s i c ch a n g e of r e e f c o m p o s i t i o n an d ac c o m p a n y i n g co n t r o l l i n g f a c t o r s oc c u r r e d on t h e wi de an d s h a l l o w , c o r a l - d o m i n a t e d O x f o r d i a n sh e l f o f e a s t e r n F r a n c e . H e r e , s ha l l o w i n g w a s a c c o m p a n i e d b y r e d u c t i o n i n t e r r i g e n e o u s i n f l u x w h i c h a l l o w e d f or t h e e s t a b l i s h m e n t o f u n i f o r m m i c r o s o l e n i d a s s o c i a t i o n s su b s t i t u t i n g f o r e a c h o t h e r b e f o r e a u t o d i f f e r e n t i a t i o n o f c o m m u n i t i e s c h a n g e d t h e e n t i r e se t t i n g ( u n p u b l i s h e d r e s u l t s , cf . Ge i s t e r an d L a t h u i l i Ë r e , 19 9 1 ; I n s a l a c o e t a l . , 1 9 9 7 ) . 2 . 4 . 4 . T h e In t e r p l a y o f C o n t r o l M e c h a n i s m s : S e l e c t e d Ex a m p l e s A f e w e x a m p l e s sh o u l d i l l u s t r a t e t h e i n t e r p l a y o f p r o c e s s e s a n d m o d e l s o u t l i n e d ab o v e . 2 . 4 . 4 a . E x a m p l e 1 . B a t h y m e t r y a n d se d i m e n t a t i o n ra t e s a s m a j o r c o n t r o l l e r s o f co r a l as s o c i a t i o n s f r o m t h e ce n t r a l L u s i t a n i a n B a s i n , P o r t u g a l . F i g u r e 15 s h o w s t h e pr i n c i p a l co r a l as s o c i a t i o n s fr o m th e Ki m m e r i d g i a n of th e ce n t r a l L u s i t a n i a n Ba s i n , w h i c h w e r e a n a l y z e d i n a se m i q u a n t i t a t i v e t o q u a n t i t a t i v e m a n n e r us i n g i m a g e an a l y s i s an d co u n t s - p e r - a r e a da t a . T h e r e e f s oc c u r at d i f f e r e n t p o s i t i o n s w i t h i n a g e n e r a l l y p r o g r a d i n g su c c e s s i o n sh a l l o w i n g u p w a r d f r o m ba s i n a l an d pr o d e l t a m a r l s an d cl a y s wi t h i n t e r c a l a t e d t u r b i d i t i c s a n d s t o n e s t o i n n e r r a m p oo l i t i c an d co r a l i f e r o u s ca r b o n a t e s ( N o s e , 19 9 5 ) . S e i s m i c d a t a su p p o r t t h e i n t e r p r e t a t i o n o f a p r o g r a d i n g sl o p e sy s t e m a n d g i v e a d d i t i o n a l ba t h y m e t r i c co n t r o l ( L e i n f e l d e r an d Wi l s o n , 19 8 9 ) . S i m i l a r t o m o d e r n Ca r i b b e a n as s o c i a t i o n s t h e s e r e e f as s o c i a t i o n s c a n b e ar r a n g e d al o n g a b a t h y m e t r i c gr a d i e n t us i n g do m i n a n t co r a l m o r p h o l o g i e s , m i c r o e n c r u s t e r as s o c i a t i o n s , an d de p t h - d i a g n o s t i c ce m e n t i n g bi v a l v e t a x a , as we l l as t h e po s i t i o n o f a s s o c i a t i o n s w i t h i n a s h a l l o w i n g u p w a r d su c c e s s i o n a n d t h e i r l a t e r a l i n t e r f i n g e r i n g w i t h h i g h - o r l o w - e n e r g y se d i m e n t s ( o o l i t i c a n d b i o c l a s t i c g r a i n s t o n e s v s . l i m e wa c k e s t o n e s an d cl a y e y m u d s ) . T h e d e e p e s t co r a l as s o c i a t i o n s a r e d o m i n a t e d b y p l a t y m i c r o s o l e n i d c o r a l s a n d a l r e a d y sh o w a h i g h p r o p o r t i o n o f l i t h i s t i d sp o n g e s . F i g u r e 1 5 , h o w e v e r , a l s o sh o w s t h a t a l t h o u g h

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FIGURE 15. Coral associations of Portugal change along a bathymetric gradient. Relative bathymetric calibration and interpretation of water energy is possible by occurrence of reef associations within shallowing-upward succession, by sedimentological features, by morphotype interpretation of diagnostic corals, and by associated fauna (compare with 11). Note that species diversity does not change uniformly along with bathymetry, but mostly is negatively correlated with terrigeneous clay content in the ground mass and positively correlated with the amount of microbial crusts, pointing to sedimentation rate as the major modifier of diversity. Highest diversities occur, however, in associations with a low but noticeable clay content, indicating the importance of nutrient availability for Jurassic reef corals (see text for further explanation). (After Nose, 1995, and Nose and Leinfelder, 1997, modified.)

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c o r a l a s s o c i a t i o n s a r e e a s i l y l i n e d u p a l o n g a b a t h y m e t r i c t r e n d , d i ve r s i t i e s a r e h i g h l y v a r i a b l e , w i t h h i g h d i v e r s i t i e s b e i n g f o u n d n o t o n l y i n sh a l l o w b u t a l s o i n d e e p e r se t t i n g s . T h e p r e s e n t e d e x a m p l e s h o w s t h a t h i g h d i v e r s i t i e s c o r r e l a t e w e l l w i t h a h i g h a m o u n t o f m i c r o b o l i t e i n t h e r e e f s a n d a r e d u c e d a m o un t o f s e d i m e n t a r y m a t e r i a l w h i c h i n d i c a t e s st r o n g l y r e d u c e d s e d i m e n t a t i o n . I t a l s o s h o w s t h a t a ve r y r e d u c e d an d p r o b a b l y i n t e r m i t t e n t i n f l u x of t e r r i g e n e o u s c l a y co r r e l a t e s wi t h es p e c i a l l y hi g h di v e r s i t i e s , wh i c h i s an ex p r e s s i o n of t h e p r e f e r e n c e f o r l o w e r m e s o t r o p h i c se t t i n g s i n U p p e r Ju r a s s i c c o r a l a ss o c i a t i o n s . O n a sm a l l e r sc a l e , h o w e v e r , sh a l l o w i n g i s n o t f u l l y u n i d i r e c t i o n a l b u t p u n c t u a t e d b y f l o o d i n g su r f a c e s a n d sh o r t - t e r m r e g r e s s i o n s , a l l o w i n g i n t e r p r e t a t i o n o f r e e f g r o w t h i n a se q u e n c e st r a t i g r a p h i c c o n t e x t ( L e i n f e l d e r , 1 9 9 3 b ; No s e , 19 9 5 ; L e i n f e l d e r an d Wi l s o n , 19 9 8 ) . R e e f s m o s t l y gr e w d u r i n g t h i r d - an d f o u r t h - o r d e r t r a n s g r e s s i o n s bu t co u l d oc c a s i o n a l l y pe r s i s t du r i n g h i g h s t a n d or ea r l y l o w s t a n d , t h o u g h i n di f f e r e n t co m p o s i t i o n ( s e e F i g . 13 ) . C h a r a c t e r i s t i c s of t r a n s g r e s s i v e co r a l r e e f s ar e : • • • • •

W i d e l y d e v e l o p e d a c r o s s t h e sh e l f , d o m i n a t i n g t h e se d i m e n t a t i o n . P u r e ca r b o n a t e . R i c h i n m i c r o b i a l c r u s t s , d e m o n s t r a t i n g l o w b a c k g r o u n d se d i m e n t a t i o n . H i g h sp e c i e s d i v e r s i t y , l o w d o m i n a n c e . M o s t l y of th e lo w - e n e r g y ty p e .

F e a t u r e s of hi g h s t a n d an d ea r l y l o w s t a n d co r a l r e e f s ar e : • G e n e r a l l y r a r e , wi t h on l y pu n c t u a t e d oc c u r r e n c e . • Mo s t l y o f l o w d i v e r s i t y , m i c r o b o l i t e f r e e t y p e s , o f t e n w i t h a c l a y e y o r silty gr oundmass. • C r u s t - f r e e de b r i s t y p e r e e f s i n t h e co n s t a n t l y wa v e - w a s h e d zo n e . 2 . 4 . 4 b . E x a m p l e 2 . S h e l f - c o n f i g u r a t i o n a n d se a - l e v e l - d r i v e n v a r i a b i l i t y o f s e d i m e n t a t i o n ra t e s a s m o t o r f o r t h e d e v e l o p m e n t o f m a j o r sp o n g e m o u n d c o m p l e x e s : T h e O x f o r d i a n G o s h e i m re e f o f S o u t h w e s t e r n G e r m a n y . I n a s i m p l i f i e d m a n n e r , U p p e r Ju r a s s i c si l i c e o u s sp o n g e m o u n d s a r e c o m p o se d c h i e f l y o f m i c r o b i a l c r u s t s , c a r b o n a t e m u d s , a n d si l i c e o u s sp o n g e s in v a r i o u s p r o p o r t i o n s . Ot h e r f a u n a o c c u r s i n v a r i a b l e p r o p o r t i o n s an d al l o w s fo r b a t h y m e t r i c ev a l u a t i o n ( F i g . 16 ) . F r o m t h e l a t e Ox f o r d i a n t o t h e ea r l y T i t h o n i a n t i m e , so u t h e r n G e r m a n y w a s c h a r a c t e r i z e d b y p a r t i c u l a r l y in t e n s e s p o n g e m u d m o u n d f o r m a t i o n . T h i s i s du e t o t h e f a c t t h a t al l o c h t h o n o u s s e d i m e n t a t i o n d e r i v e d f r o m sh a l l o w - w a t e r c a r b o n a t e f a c t o r i e s t o t h e n o r t h , e a s t , a n d no r t h w e s t wa s l o w en o u g h t o al l o w m o u n d f o r m a t i o n . I n t h e S w i s s J u r a s s i c a n d p a r t i c u l a r l y t h e s o u t h P o r t u g u e s e A l g a r v e Ba s i n , c a r b o na t e f a c t o r i e s w e r e m u c h c l o s e r t o t h e su i t a b l e d e p t h p r o v i n c e s o f t h e o u t e r r a m p d u e t o t h e st e e p e n e d c h a r a c t e r o f t h e r a m p s , w h i c h d i d n o t o r o n l y o c c a s i o n a l l y a l l o w f o r m o u n d f o r m a t i o n . On t h e ot h e r ha n d , a ce r t a i n am o u n t of a l l oc h t h o n o u s ca l c a r e o u s m u d s we r e ne c e s s a r y t o h e l p i n g a m o u n d a c c u m u l a t e ( L e i n f e l d e r an d Ke u p p , 19 9 5 ) .

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FIGURE 16. Architecture and sequential interpretation of a major compositeósiliceous spongeómicrobolite mudmound complex of the western Swabian Alb, southern Germany. Growth of the entire complex is related to reduction of sediment influx during a third-order sea-level rise. Episodes of lateral expansion of the composite complex are correlative with fourth- and fifth-order floodings. The (late?) highstand of T3 stopped the growth of the entire complex due to raised import of allochthonous calcarous mud from shallow-water carbonate factories. See text for details.

(Note Figure is originally in landscape format, it was turned here 90° for better readability of this online-copy)

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I n so u t h e r n G e r m a n y m a n y m o u n d s t h i c k e r t h a n a b o u t 1 0 m a r e i n t e n s e l y r e c r y s t a l l i z e d , d o l o m i t i z e d , o r d e d o l o m i t i z e d , a n d h e n c e d o n o t sh o w a n y c l u e s a s t o t h e i r e x a c t or i g i n . Ox f o r d i a n m o u n d s ar e ge n e r a l l y be t t e r p r e s e r v e d , wh i c h i s pr o b a b l y du e t o t h e f a c t t h a t i n t e r m i t t e n t cl a y e y t e r r i g e n e o u s se d i m e n t a t i o n p r e v e n t e d l a t e r d i a g e n e t i c n e o m o r p h o s i s . T h e O x f o r d i a n m o u n d st r u c t u r e a t G o s h e i m , w e s t e r n S w a b i a n A l b , i s r e m a r k a b l e i n v a r i o u s wa y s . It is on e of th e fe w mo u n d s w h e r e ba s e , t o p an d la t e r a l ma r g i n s a r e a l l o b s e r v e d i n o u t c r o p . I t sh o w s a l l i n t e r n a l a r c h i t e c t u r a l a n d s e d i m e n t o l o g i c a l f e a t u r e s an d i s co n s t r a i n e d by a hi g h - r e s o l u t i o n a m m o n i t e s t r a t i g r a p h i c f r a m e w o r k . F i g u r e 1 6 s h o w s t h e p r o m i n e n t f e a t u r e s o f th e m o u n d . T h e m o u n d i s a c o m p o s i t e st r u c t u r e c o m p o s e d o f c l u s t e r e d a n d a m a l g a m a t e d sm a l l b i o h e r m s o f m e t e r - s i z e . T h e b i o h e r m s a r e v e r y r i c h i n t h r o m b o l i t i c m i c r o b i a l c r u s t ( i n so m e c a s e s u p t o 8 0 % ) a n d c o n t a i n d e n s e m i c r i t e a n d si l i c e o u s sp o n g e s i n v a r i a b l e a m o u n t s . S i l i c e o u s sp o n g e s a r e c o m p o s e d o f a f a i r l y h i g h - d i v e r s i t y f a u n a , w i t h 8 8 % o f t h e sp o n g e s b e l o n g i n g t o t h e He x a c t i n e l l i d a an d on l y 1 2 % t o t h e l i t h i s t i d de m o s p o n g e s , w h i c h m a y r e f l e c t b o t h a f a i r l y d e e p se t t i n g a n d f r e q u e n t t h o u g h r e d u c e d b a c k g r o u n d s e d i m e n t a t i o n . A l l sh a p e s a n d s i z e s o f sp o n g e m o r p h o l o g i e s o c c u r , w i t h t u b e - , v a s e - , a n d d i s h - s h a p e d sp o n g e s m e a s u r i n g u p t o 2 m i n d i a m e t e r o r h e i g h t . A c c o m p a n y i n g f a u n a i s r i c h as w e l t , wi t h oc c a s i o n a l bu r r o w i n g bi v a l v e s , w h i c h i n d i c a t e so f t g r o u n d s . H a r d su b s t r a t e s , p a r t i c u l a r l y t h e m i c r o b i a l c r u s t s , w e r e in h a b i t e d by m i c r o e n c r u s t e r s of th e T u b i p h y t e s a s s o c i a t i o n , in c l u d i n g l a r g e t e r e b e l l i d w o r m t u b e s , a n d b y a g r e a t v a r i e t y o f b r a c h i o p o d s a nd e p i b e n t h i c , m o s t l y p e c t i n i d , b i v a l v e s . Be l e m n i t e s an d a m m o n o i d s ar e f r e q u e n t b u t o f t e n e n r i c h e d t o se v e r a l l e v e l s , w i t h so m e sm a l l f o r m s su c h a s G l o c h i c e r a s c e r t a i n l y r e p r e s e n t i n g bo t t o m r e l a t e d mo u n d dw e l l e r s . T h e l a t e r a l ex t e n s i o n of t h e en t i r e m ou n d s t r u c t u r e r e a ch e s i t s m a x i m u m at i t s ba s e , gi v i n g th e en t i r e mo u n d gr o s s l y a py r a m i d a l s h a p e wi t h a ba sa l la t e r a l e x t e n s i o n of ab o u t 20 0 m an d a he i g h t of ne a r l y 50 m ( F i g . 16 ) . T h e ba s a l m o u n d s a r e a r r a n g e d i n a st r i n g - o f - p e a r l f a s h i o n , p o s i t i o n e d d i r e c t l y a b o v e a b e d r i c h i n am m o n o i d s , be l e m n i t e s , ox y d i z e d py r i t e no d u l e s , au t h i g e n i c g l a u c o n i t e , an d C h o n d r i t e s b u r r o w s , wh i c h pr o v i d e ev i d e n c e of t h e ce s s a t i o n o f se d i m e n t a t i o n a n d p o s s i b l y e v e n sl i g h t o x y g e n d e p l e t i o n , a t l e a s t i n t h e t o p m o s t se a f l o o r . T h e b a s a l m u d s a r e p a r t i c u l a r l y r i c h i n m i c r o b o l i t e c r u s t s a n d t h e l a r g e s t sp o n g e s o f t h e e n t i r e c o m p l e x a l s o a p p e a r i n t h i s l e v el , e v i d e n c i n g f a v o r a b l e co n d i t i o n s ov e r at l e a s t m a n y hu n d r e d s t o t h o u sa n d s of y e a r s . F o l l o w i n g t h i s ba s a l m e g a b i o s t r o m e , co m p o s e d of i n d i v i d u a l s ma l l b i o h e r m s , m o u n d de v e l o p m e n t wa s r e s t r i c t e d t o a na r r o w ar e a t o ag a i n ex p a n d l a t e r a l l y se v e r a l t i m e s . F i g u r e 1 6 sh o w s t h a t t h e f r a c t a l p a t t e r n o f m o u n d d e v e l o p m e n t i s c a u s e d b y t h e su p e r p o s i t i o n o f se a - l e v e l c y c l e s o f d i f f e r e n t m a g n i t u d e , w h i c h m o d u l a t e d se d i m e n t i n f l u x . T h e e n t i r e st r u c t u r e c a n b e r e f e r r e d t o a t h i r d - o r d e r se a - l e v e l r i s e a n d i t a c t u a l l y c o r r e l a t e s w i t h t h e t r a n s g r e s s i v e sy s t e m t r a c t o f t h e P o n s o t a n d V a i l ( 1 9 9 1 ) d e p o s i t i o n a l sy s t e m b e t w e e n 1 4 6 . 5 Ma a n d 1 4 5 . 2 Ma . Ba s e d o n t h e L e i n f e l d e r a n d K e u p p ( 1 9 9 5 ) m o d e l t h i s t r a n s g r e s s i o n bo t h r e d u c e d t e r r i g e n e o u s i n f l u x as we l l a s ca r b o n a t e m u d e x p o r t f r o m t h e r e m o t e sh a l l o w - w a t e r c a r b o n a t e f a c t o r y , w h i c h i nc r e a s e d

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a g a i n d u r i n g h i g h s t a n d , c a u s i n g b u r i a l o f t h e m o u n d st r u c t u r e b y a l l o c h t h o n o u s c a r b o n a t e m u d s ( h i g h s t a n d sh e d d i n g ) . T h i s c o r r e l a t i o n su g g e s t s t h a t t h e O x f o r d i a n d e e p sh e l f s e d i m e n t s w e r e l a r g e l y o f a l l o c h t h o n o u s o r i g i n r a t h e r t h a n r e p r e s e n t i n g h e m i p e l a g i c p l a n k t i c o o z e . A c t u a l l y , r e l i cs o f c o c c o l i t h s ar e ex t r e m e l y r ar e , wh i c h po s s i b l y do e s not r e p r e s e n t pr e s e r v a t i o n a l b i a s . E s t a b l i s h m e n t as we l l as pu l s e s of l a t e r a l ex p a n s i o n of t h e m o un d s t r u c t u r e s c o r r e l a t e wi t h am m o n o i d co n c e n t r a t i o n s an d f o r m a t i o n of a u t h i g e n i c gl a u c o n i t e r e l a t a b l e t o f o u r t h - an d hi g h e r - o r d e r f l o o d i ng ev e n t s . T h e Go s h e i m m o u n d t h u s i s a ke y ex a m p l e f o r an a l y z i n g t h e or i g i n of J u r a s s i c sp o n g e - r i c h m u d m o u n d s . I t h i g h l i g h t s t h e i m p o r t a n c e o f st r o n g l y r e d u c e d b u t n o t i c e a b l e i n t e r m i t t e n t i n f l u x o f a l l o c h t h o n o u s se d i m e n t a t i o n . T h e r e w a s n o o b v i o u s st r u c t u r a l c o n t r o l . T h i s a l s o a p p e a r s t r u e f o r m o s t i f n o t a l l o t h e r sp o n g e m o u n d s i n so u t h e r n G e r m a n y . T h e l a t e r a l i n t e r f i n g e r i n g w i t h b e d d e d m u d d y l i m e s t o n e s i s ev i d e n c e of t h e co m p o s i t e ch a r a c t e r of t h e m o u n d t h a t d e s p i t e i t s c u m u l a t i v e h e i g h t o f a b o u t 5 0 m n e v e r r o s e a b o v e t h e se a f l o o r m o r e t h a n a c o u p l e o f m e t e r s . A c o m p o s i t e a n a l y s i s o f b i o s t r a t i g r a p h ic d a t a , m a t u r i t y an a l y s i s o f au t h i g e n i c gl a u c o n i t e s , an d i n d e p e n d e n t gr o w t h r a t e m e a s u r e m e n t s of m i c r o b o l i t e s f r o m m e a s u r a b l e co r a l r e e f s i n d i c a t e s th a t m o u n d g r o w t h wa s ar o u n d 1 m m / y e a r , bu t pr e s e r v a t i o n po t e n t i a l wa s o n ly 15 t o 20 % . 2 . 4 . 4 c . E x a m p l e 3 . L o w - d i v e r s i t y sp o n g e b i o s t r o m e s a s i n d i c a t o r s o f s t a r v e d o l i g o t r o p h i c sh e l v e s . I n e a s t e r n S p a i n , m o r e t h a n 7 0 , 0 0 0 k m 2 i s c o v e r e d by a un i q u e an d e x t r e m e l y u n i f o r m as s o c i a t i o n of si l i c e o u s sp o n g e s o f Mi d - O x f o r d i a n a g e . T h i s a s s o c i a t i o n w a s r e c e n t l y d e s c r i b e d i n d e ta i l b y K r a u t t e r ( 1 9 9 5 , 19 9 7 ) . T h e l a t e r a l l y ex t e n s i v e bi o s t r o m a l un i t i s o n l y a co u p l e o f m e t e r s t h i c k b u t n e v e r t h e l e s s sp a n s se v e r a l a m m o n i t e z o n e s ( m a x i m u m c o r d a t u m t o p l a n u l a z o n e , h e n c e si x a m m o n i t e z o n e s ) . E x c e p t f o r a v e r y f e w e x c e p t i o n s n o r e l i e f i s f o r m e d a n d t h e u n i t i s c o m p o s e d a l m o s t so l e l y o f d i s h - s h a p e d sp o n g e s c o m p r i s i n g u p t o 9 0 % o f r o c k v o l u m e . D e s p i t e a s t r o n o m i c a l in d i v i d u a l nu m b e r s , th e f a u n a is of lo w di v e r s i t y . Ni n e t y p e rc e n t of t h e f a u n a a r e r e p r e s e n t e d b y h e x a c t i n o s a n sp o n g e s c o m p r i s i n g 2 4 sp e c i e s . N e a r l y a l l t h e s e sp e c i e s a r e k n o w n f r o m o t h e r sp o n g e r e e f l o c a l i t i e s , b u t t h e a c c o m p a n y i n g t a x a a r e m i s s i n g a n d t h r e e g e n e r a st r o n g l y d o m i n a t e . E i g h t y p er c en t of al l spo n ge s ar e of the di s h sha p e. Th e ra ri t y of enc r us t in g or g a n i s m s o n sp o n g e s , su c h a s se r p u l i d s , b r y o z o a n s , o r o y s t e r s , i s r e m a r k a b l e , a l t h o u g h t h e s e f o r m s oc c u r s p o r a d i c a l l y . T h e on l y ot h e r el e m e n t s wo r t h m e n t i o n i n g ar e t e r e b r a t u l i d b r y o z o a n s a n d t h e r e g u l a r e c h i n o i d R h a b d o c i d a r i s rh o d a n i , w h i c h i s i n d i c a t i v e of di m i n i s h e d ox y g e n av a i l a b i l i t y . S i m i l a r l y , l e v e l s o f C h o n d r i t e s b u r r o w s a l s o i n d i c a t e t h a t se d i m e n t w a s o c c a s i o n a l l y d e p l e t e d i n o x y g e n . J u d g i n g f r o m t h e l o n g t i m e s p a n i n v o l v e d a n d t h e f r e q u e n t i r o n o x i d e cr u s t s w i t h h a r d g r o u n d s , n o b a c k g r o u n d se d i m e n t a t i o n e x i s t e d . I n t e r e s t i n g l y , m i c r o b o l i t i c bi o h e r m s di d no t de v e l o p , al t h o u g h m i c r o b o l i t i c cr u s t s oc c u r as t h i n l a y e r s . T h e p e c u l i a r sp o n g e f a u n a o f t h i s r e e f w a s a d a p t e d t o v e r y o l i g o t r o p h i c c o n d i t i o n s t h a t r e l a t e t o t h e l a c k o f t e r r i g e n e o u s i n f l u x . L a c k o f n ut r i e n t s k e p t m i c r o b o l i t e de v e l o p m e n t at a l o w pa c e , an d t o g e t h e r wi t h t h e l a c k o f a l l o c h t h o n o u s se d i m e n t a t i o n h e l p s e x p l a i n w h y b i o h e r m s d i d n o t d e v e l o p .

292

Ch a p te r 8

2 . 4 . 4 d . E x a m p l e 4. O c e a n o g r a p h i c ch a n g e s du r i n g t h e hy p s e l o c y c l u m d i v i s u m t r a n s g r e s s i o n . O n e o f t h e m o s t p u z z l i n g f e a t u r e s o f U p p e r Ju r a s s i c r e e f de v e l o p m e n t is th e de v e l o p m e n t of pu r e mi c r o b o l i t e r e e f s r e l a t e d to e u t r o p h i c a t i o n a n d / o r o x y g e n d e p l e t i o n ( s e e S e c t i o n 2 . 4 . 1 ) . Ma n y o f t h e s e r ee f s hav e be en de s cr i be d in de ta i l els e wh e re (L e in f el d er e t al. , 1 99 3 a, b ; No s e , 1 9 9 5 ; S c h m i d , 1 9 9 6 ) . Co r a l a n d sp o n g e r e e f s c a n b e v e r y r i c h i n m i c r o b i a l c r u s t , wh i c h he r e i s no t co n s i d e r e d a pu r e m i c r o b o l i t e r e e f be c a u s e m a c r o o r g a n i s m s a n d m i c r o b o l i t e c r u s t s st r o n g l y i n t e r f i n g e r . H o w e v e r , t h e r e a r e r e e f s c o m p o s e d n e a r l y c o m p l e t e l y o f p u r e t h r o m b o l i t i c m i c r o b o l i t e o r o f a re e f s t r u c t u r e wi t h up w a r d al t e r n a t i o n of pu r e m i c r o b o l i t e a n d co r a l - m i c r o b o l i t e . A b o v e i t w a s st a t e d t h a t p u r e m i c r o b o l i t e d e v e l o p m e n t m i g h t b e d u e t o a v a r i e t y o f n o n b i o l o g i c a l f a c t o r s , su c h a s i n c r e a s e d o r d e c r e a s e d sa l i n i t y o r i n t e r t i d a l p o s i t i o n . W e f o c u s h e r e o n l y o n e x a m p l e s w h e r e su c h m e c h a n i s m s c a n b e e x c l u d e d a n d w h e r e c r i t e r i a f o r o x y g e n d e p l e t i o n , s u c h a s c l u st e r s o f d y s a e r o b i c ep i b e n t h i c bi v a l v e s , au t h i g e n i c gl a u c o n i t e , f r a m b o i d a l p y r i t e , or s e c o n d a r y gy p s u m ar e av a i l a b l e . T h e m o s t i n t e r e s t i n g ep i s o d e wa s t h a t of t h e l a t e H y p s e l o c y c l u m - e a r l y D i v i s u m z o n e s . H e r e su c h r e e f s d e v e l o p e d w i d e l y i n I b e r i a an d co r r e l a t e el s e w h e r e wi t h ot h e r p e c u l i a r r e e f s . T h i s t i m e w a s c h a r a c t e r i z e d b y a st r o n g t r a n s g r e s s i o n ( H a q e t a l . , 1 9 8 8 ; H a n t z p e r g u e , 1 9 8 8 ; P o n s o t an d Va i l , 19 9 1 ; L e i n f e l d e r , 19 9 3 b ) p r o m o t i n g vi g o r o u s r e e f g r o w t h , d e s p i t e t h e f a c t t h a t i n m a n y a r e a s t h e L o w e r Ki m m e r i d g i a n an d ea r l y Up p e r K i m m e r i d g i a n st a g e s w e r e d o m i n a t e d b y t e r r i g e n e o u s d e p o s i t s . H o w e v e r , m a n y I b e r i a n sh e l f se c t i o n s d o n o t sh o w n o r m a l t r e n d s f o r r e e f s l i k e d u r i n g t h e m a j o r Ox f o r d i a n o r l a t e Ki m m e r i d g i a n t r a n s g r e s s i o n s . S h a l l o w wa te r co r a l r e e f s w e r e no t ac c o m p a n i e d by d e e p e r - w a t e r sp o n g e mo u n d s bu t ra t h e r by p u r e m i c r o b o l i t e s . T h e p u r e m i c r o b o l i t e s o c c a s i o n a l l y e x h i b i t t h i n ho r i z o n s o f s i l i c e o u s sp o n g e s . T h e s e m i c r o b o l i t e s o c c u r r e d b o t h i n c o n s i d e r a b l y d e e p w a t e r s a s w e l l a s i n m o d e r a t e l y d e e p sl o p e se t t i n g s . T h e c l u s t e r s o f m e t e r s c a l e d cl u b - s h a p e d mi c r o b o l i t e s at Co t o v i o (O x f o r d i a n ) or th e 30 - m th i c k L o w e r K i m m e r i d g i a n Ro c h a t h r o m b o l i t i c o f so u t h e a s t e r n P o r t u g a l ( F i g . 1 7 d ) a r e go o d ex a m p l e s ( L e i n f e l d e r e t al . , 1 9 9 3 a ) . Ho w e v e r , ev e n co r a l r e e f gr o w t h i n so m e e x a m p l e s b e c a m e i n t e r r u p t e d b y p u r e m i c r o b o l i t e g r o w t h sh o w i n g c h a r a c t e r i s t i c s of ox y g e n de p l e t i o n . E x a m p l e s ar e t h e T o r m o n r e e f o f ea s t e r n S p a i n ( F i g . 17 a ) or t h e S e r r a I s a b e l r e e f s of ce n t r a l P o r t u g a l ( F i g . 1 7 c ) ( Le i nf e ld e r e t al. , 1 99 3 a, b ; Wer n er e t al. , 1 99 4 ). Ou t si d e Ibe r ia , re ef s al so ma y s h o w pe c u l i a r i t i e s du r i n g th i s ti m e in t e r v a l of th e la t e E a r l y K i m m e r i d g i a n ( H y p s e l o c y c l u m - D i v i s u m ch r o n s ) . Co e v a l co r a l - m i c r o b o l i t e r e e f s at L a R o c h e l l e , w h i c h r e c e n t l y w e r e s t u d i e d b y T a y l o r a n d P a l m e r ( 1 9 9 4 ) , S ch m i d ( 1 9 9 6 ) , a n d W e r n e r ( p e r s o n a l c o m m u n i c a t i o n ) , g r e w i n sl i g h t l y d e e p e r w a t e r , a s ev i d e n c e d by t h e m i c r o e n c r u s t e r as s o c i a t i o n . T h e m i c r o b o l i t e de v e l o p m e n t i s un u s u a l l y th i c k an d la r g e l y su b s t i t u t e s co r a l gr o w t h in th e la t e st a g e s of r e e f g r o w t h , wh i c h to g e t h e r wi t h a h i g h in d i v i d u a l nu m b e r of nu t r i e n t - l o v i n g e p i f a u n a ( s e r p u l i d s , l a r g e oy s t e r s ) hi n t s a t f a i r l y el e v a t e d nu t r i e n t av a i l a b i l i t y , a l t h o u g h dy s a e r o b i c pu l s e s ar e no t di r e c t l y do c u m e n t e d he r e ( F i g . 1 7 b ) . I n s o u t h w e s t e r n G e r m a n y , t h e sa m e t r a n s g r e s s i o n g a v e r i s e t o t h e p a r t i a l i n t e r r u p t i o n o f t e r r i g e n e o u s se d i m e n t a t i o n a n d t o t h e d e v e l o p m e n t o f p e c u l i a r

Ju ra ssi c Re e f Ec o sy ste m

293

s m a l l s p o n g e - b r a c h i o p o d r e e f s k n o w n as , , l a c u n o s a - S t o t z e n . ì He x a c t i n e l l i d d o m i n a n c e an d m i c r o e n c r u s t e r s i n d i c a t e t h a t t h e s e r e e f s ce r t a i n l y w e r e p o s i t i o n e d i n w a t e r s n o t sh a l l o w e r t h a n a b o u t 6 0 t o 8 0 m , b u t n u t r i e n t i n c r e a s e m i g h t b e in d i c a t e d by th e do m i n a n c e of r h y n c h o n e l l i d br a c h i o p o d s . S i n c e t h e ba t h y m e t r y of t h e s e r e e f s ca n be as s e s s e d by t h e f a u n a l c h a r a c t e r i s t i c s of th e ox i c pa r t s of r e e f d e v e l o p m e n t , th e mi n i m u m po s i t i o n of a nu t r i c l i n e , wh i c h at l e a s t i n I b e r i a wa s as s o c i a t e d w i t h an ox y c l i n e , ca n be r o u g h l y o u t l i n e d ( F i g . 1 8 ) . I t w a s st r o n g l y f l u c t u a t i n g b u t r e a c h e d w a t e r s a s s h a l l o w a s a b o u t 3 0 m i n c e n t r a l P o r t u g a l , 4 0 m i n so u t h w e s t e r n F r a n c e , 6 0 m i n so u t h e r n P o r t u g a l , a n d p o s s i b l y 8 0 m i n so u t h w e s t e r n G e r m a n y . H o w e v e r , s u c h sh a l l o w n e s s o f t h e n u t r i c l i n e w a s l a r g e l y r e s t r i c t e d t o t h e H y p s e l o c y c l u m - D i v i s u m t r a n s g r e s s i o n a n d i s e v i d e n c e o f st r o n g r e d u c t i o n i n o c e a n w a t e r c i r c u l a t i o n w h i c h m i g h t b e a n e f f e c t o f t h e c l i m a t i c e q u i l i b r a t i o n o f a st r o n g l y r i s i n g se a l e v e l ( L e i n f e l d e r , 1 9 9 4 a ) . 2 . 4 . 4 e . O t h e r E x a m p l e s . R e e f s a s i n d i c a t o r s o f b a s i n st r u c t u r e u n d t e c t o n i c a c t i v i t y . T h e r e a r e m a n y o t h e r st u d i e d e x a m p l e s d e m o n s t r a t i n g t h e r o l e o f t h e g e n e r a l t e c t o n i c a n d p a l e o g e o g r a p h i c se t t i n g o n r e e f d e v e l o p m e n t . T h e L us i ta n ia n Ba si n of Po rt u ga l pr ov i de s ma ny ex a mp l es we r e ree f s are in di c a t i v e o f b a s i n c o n f i g u r a t i o n , t e c t o n i c se t t i n g , w a t e r c i r c u l a t i o n , a n d se a - l e v e l d e v e l o p m e n t . A m o n g t h e e x a m p l e s a r e r e e f g r o w t h w i t h i n si l i c i c l a s t i c f a n d e l t a s s h e d i n t o st r i k e - s l i p b a s i n s a s i n d i c a t o r s o f t e c t o n i c q u i e s c e n c e , p l a t f o r m d e v e l o p m e n t a s i n d i c a t o r s o f r i s i n g sa l t p i l l o w s , a n d p a t t e r n s o f c o n t e m p o r a n e o u s r e e f a n d si l i c i c l a s t i c s e d i m e n t a t i o n i n d i c a t i v e o f l o n g s h o r e c u r r e n t s y s t e m s ( L e i n f e l d e r , 19 9 4 b , 19 9 7 ) . E x a m p l e s f r o m F r a n c e , S w i t z e r l a n d , an d G e r m a n y ar e i n pr e p a r a t i o n f o r pu b l i c a t i o n .

3 . I n t r a j u r a s s i c R e e f D e v e l o p m e n t : Fa u n i s t i c E v o l u t i o n o r E n v i r o n m e n t a l Ch a n g e ? L e i n f e l d e r ( 1 9 9 4 a ) di s c u s s e d th e te m p o r a l e v o l u t i o n of r e e f s th r o u g h o u t t h e Ju r a s s i c p e r i o d a n d st r e s s e d t h e f a c t t h a t t h e a b u n d a n c e o f r e e f s g e n e r a l l y h a s i n c r e a s e d wi t h t i m e , al t h o u g h t h e r e ex i s t co n s i d e r a b l e di f f e r e n c e s i n t h e t r e n d b e t w e e n s p o n g e a n d co r a l r e e f s an d di f f e r e n c e s be t w e e n t h e no r t h e r n a n d so u t h e r n T e t h y s sh e l f . Ba s e d o n t h i s c o m p i l a t i o n a n d so m e n e w d a t a , a b r i e f s u m m a r y is gi v e n he r e . 3.1.

E v o l u t i o n a r y As p e c t s of Re e f Or g a n i s m s

S i l i c e o u s sp o n g e a s s o c i a t i o n s a n d si l i c e o u s sp o n g e r e e f s a r e k n o w n f r o m a l l t h r e e e p o c h s o f t h e Ju r a s s i c . O n t h e n o r t h e r n T e t h y a n s h e l f , t h e y s t r o n g l y i n c r e a s e i n a b u n d a n c e d u r i n g t h e Mi d - a n d L a t e Ju r a s s i c t i m e , w h e r e a s o n t h e s o u t h e r n T e t h y a n sh e l f , t h e y o c c u r r e d m o r e w i d e l y d u r i n g E a r l y Ju r a s s i c t i m e . W i t h th e ex c e p t i o n of th e ly c h n i s k i d sp o n g e s , kn o w n si n c e th e la t e r pa r t of

294

Ch ap ter 8

a) Coral thrombolite at Tormón, Celtiberian Basin, eastern Spain

8m

coral-stromatoporoid thrombolite

oxic

pure thrombolite

dysoxic / eutrophic

coral thrombolite

oxic

pure thrombolite

dysoxic / eutrophic

ca. 20 m

b) Typical coral-microbolite reef at La Rochelle, sw. France massive corals 2nd thrombolite generation large oysters

crust-rich debris aprons

5-12 m

occasional pyrite nodules

caves with cryptic encrusters

1st thrombolite generation phaceloid and ramose corals

FIGURE 17. Examples of microbolite reefs from the late Early Jurassic (HypselocyclumóDivisum chron) of southwestern Europe. (a) Repetitive succession of coralómicrobolite to pure microbolite reef growth. (b) Coral reef with upward, outward, and downward increasing participation of microbolite crusts. (c) Lateral variability of a condensed level, partly with telescoped successions of dysaerobic and oxygenated reef facies. (d) Thick complex of largely pure microbolite. Siliceous sponges may occur but are refined to distinct leveis.

M i d - J u r a s s i c t i m e , a l l o t h e r g r o u p s o f t h e s e u l t r a c o n s e r v a t i v e o r g a ni s m s e x i s t e d p r i o r t o t h e Ju r a s s i c ( M e h l , 1 9 9 2 ) . A l t h o u g h e x a c t n u m b e r s o f t a x a a r e n o t a v a i l a b l e t o d a t e , t h e o c c u r r e n c e o f l o w e r Ju r a s s i c si l i c e o u s s p o n g e m o u n d s d e m o n s t r a t e s t h a t t h e g e n e r a l p o s s i b i l i t y o f sp o n g e r e e f f o r m a t i o n e x i s t e d t h r o u g h o u t t h e en t i r e J u r a s s i c pe r i o d . A ce r t a i n ev o l u t i o n a ry i n c r e a s e o f sp o n g e t a x a t h e r e f o r e w a s c a u s e d b y i n c r e a s i n g a v a i l a b i l i t y o f s p o n g e r e e f h a b i t a t s r a t h e r th a n vi c c e ve r s a . C o r a l s su f f e r e d a s e v e r e e x t i n c t i o n a t t h e T r i a s s i c - J u r a s s i c b o u n d a r y ( s e e C h a p t e r 7 , t h i s v o l u m e ) , a n d t h e r e f o r e a r e e x t r e m e l y r a r e i n t h e e a r ly p a r t o f t h e E a r l y Ju r a s s i c . E l m i ( 1 9 8 7 ) m e n t i o n s a sm a l l c o r a l r e e f o c c u r r e n c e o f

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c) Lateral variability of the Serra Isabel unit, Lusitanian Basin, central Portugal

secondary gypsum

coral and crinoid meadows

telescoping of infaunal to epifaunal bivalve assemblages

marls crust-rich coral ammonite limestone concentrations

cluster of the dysaerobic epibenthic Aulacomyella

ca 10 m

early diagenetic ferric concretions and crusts

dysaerobic thrombolitic microbolites

100s of meters to kilometers

d) The Rocha microbolite reef, eastern Algarve, Portugal

Jordana

sponge spicule wackestones pure thrombolite, very glauconitic, often interwoven with Tubiphytes layers cup-shaped hexactinosan meadow, within marl layer debris facies, with ammonites, coal, pyritic nodules

5m

occasional layers with hexactinosan sponges ammonitic marls and micrites

Peral 100s of meters to kilometers

at outcrop

partly reconstructed

FIGURE 17. Continued

H e t t a n g i a n a g e i n F r a n c e , b u t i t i s st i l l a w a i t i n g c l o s e r i n s p e c t i o n . B e s i d e s t h i s e n i g m a t i c He t t a n g i a n ex a m p l e , e a r l i e s t co r a l r e e f oc c u r r e n c e s ar e f r o m th e S i n e m u r i a n a n d a r e a l l si t u a t e d o n e x o t i c t e r r a n e s l a t e r a c c r e t e d t o t h e w e s t e r n m a r g i n o f N o r t h A m e r i c a ( S t a n l e y a n d Mc R o b e r t s , 1 9 9 3 ) , w h i c h w a s i n t e r p r e t e d b y S t a n l e y a n d Be a u v a i s ( 1 9 9 4 ) an d S t a n l e y ( 1 9 9 6 ) as an ex p r e s s i o n o f l o n g - t e r m i s o l a t i o n o f c o r a l s , su r v i v i n g f r o m T r i a s s i c t i m e , w h i l e i n h a b i t i n g e x o t i c i s l a n d s of t h e pa l e o - P a c i f i c . F r o m t h e P l i e n s b a c h i a n an d pa r t i c u l a r l y T o a r c i a n o n w a r d , c o r a l r e e f s b e c a m e m o r e f r e q u e n t a n d i t i s si n c e t h at t i m e t h a t a v a i l a b l e c o r a l t a x a w e r e su f f i c i e n t t o f o r m v a r i a b l e t y p e s o f c o r a l r e e f s . N u m b e r s of ge n e r i c t a x a , as co m p i l e d f r o m t h e l i t e r a t u r e ( r e f e r e n c e s i n L e i n f e l d e r , 1 9 9 4 a ) , y i e l d a b o u t 6 0 g e n e r a f o r t h e E a r l y Ju r a s s i c w i t h a l l i m p o r t a n t m a j o r g r o u p s st i l l e x i s t i n g . A b o u t 1 0 0 g e n e r a w e r e a v a i l a b l e d u r i n g t h e Mi d - J u r a s s i c w i t h a b o u t 1 3 0 g e n e r a i n t h e L a t e Ju r a s s i c ( d a t a f r o m v a r i o u s s o u r c e s , c o m p i l e d i n L e i n f e l d e r , 1 9 9 4 a ) . D e s p i t e t h e f a c t t h a t J u r a ss i c c o r a l s

FIGURE 18. The contemporaneous reefs shown in Fig. 17 are interpreted as reflecting eutrophication pulses that were frequently accompanied by oxygen depletion. Aerobic parts of the reefs allowed for bathymetric interpretation and depth mapping of a nutricline-oxycline that occasionally were as shallow as 30 to 40 m in same examples.

(Note Figure is originally in landscape format, it was turned here 90° for better readability of this online-copy)

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u r g e n t l y n e e d t a x o n o m i c r e v i s i o n , i t i s o b v i o u s a g a i n t h a t t h e i n c r e as e i n c o r a l r e e f ab u n d a n c e ne e d no t ne c e s s a r i l y be du e t o an ad a p t i v e r a d i a t i o n o f co r a l s . N e v e r t h e l e s s , t h e c o r a l f a u n a d i v e r s i f i e d a n d t h e d e v e l o p m e n t o f sp e c i a l i z e d t a x a su c h a s v e r y m o r p h o v a r i a b l e sp e c i e s o r b r a c k i s h w a t e r sp e c i a l i s t s a l l o w e d f o r t h e co n q u e s t of pr e v i o u s l y ho s t i l e en v i r o n m e n t s , an d t h i s wa s a p o s i t i v e e v o l u t i o n a r y f e e d b a c k o n t h e si z e o f t h e , , r e e f w i n d o w ì ( s e e S e c t i o n 4 ) . 3 . 2 . S e a - L e v e l De v e l o p m e n t T h e e x p a n s i o n o f sp o n g e r e e f s a n d c o r a l r e e f s o n t h e n o r t h e r n T e t h y s sh e l f c o r r e l a t e s co n s i d e r a b l y we ll wi t h ge n e r a l s e a - l e v e l r is e ( F i g . 19 ) . Du r i n g E a r l y J u r a s s i c t i m e t h e r e wa s co n s i d e r a b l e t e r r i g e n e o u s i n f l u x of cl a s t i c s , pe r m i t t i n g r e e f g r o w t h o n l y i n m o r e o r l e s s p r o t e c t e d , w i d e p l a t f o r m a r e a s su c h a s c e n t r a l P o r t u g a l ( n e w d i s c o v e r y o f sp o n g e f a c i e s : D u a r t e a n d K r a u t t e r , 1 9 9 8 ) a n d s o u t h e r n F r a n c e ( c o r a l r e e f s ) . S o u t h e r n G e r m a n y st i l l w a s d o m i n a t e d b y t e r r i g e n e o u s se d i m e n t s d e r i v e d f r o m t h e V i n d e l i c i a n b a s e m e n t u p l i f t a n d t h i s p r e v e n t e d r e e f g r o w t h . S e a l e v e l k e p t r i s i n g w e l l i n t o L a t e Ju r a s s i c t i m e , i n c r e a s i n g l y i m p r o v i n g t h e e n v i r o n m e n t a l c o n d i t i o n s su i t a b l e f o r t h e g r o w t h o f b o t h c o r a l a n d s p o n g e r e e f s b y f u r t h e r r e d u c i n g t e r r i g e n e o u s i n f l ux . O n l y d u r i n g L a t e Ju r a s s i c t i m e w e r e t h e sh e l f a r e a s f l o o d e d w i d e l y e n o u g h t o p r o v i d e su i t a b l e c a r b o n a t e - d o m i n a t e d o u t e r r a m p se t t i n g s o n a l a r g e sc a l e , w h e r e s i l i c e o u s sp o n g e m o u n d s w o u l d d e v e l o p i n a m o r e t h a n 7 0 0 0 k m w i de b e l t e x t e n d i n g f r o m Ru m a n i a t o T e x a s . P r o d u c t i v i t y o f t h e s e c a r b o n a t e sh e l v e s w a s h i g h e r t h a n t h e i n c r e a se o f a c c o m m o d a t i o n b y t h e g e n e r a l se a - l e v e l r i s e so t h a t a g e n e r a l l y sh a l l o w i n g su c c e s s i o n d e v e l o p e d . T h e p e a k o f r e e f f o r m a t i o n d u r i n g t h e O x f o r d i a n d i d n o t c o i n c i d e w i t h t h e p e a k i n se a - l e v e l r i s e t h a t o c c u r r e d l a t e r , at t h e Ki m m e r i d g i a n ó T i t h o n i a n bo u n d a r y ( H a q e t al . , 1 9 8 8 ) . T h e r e l a t i v e r e t r e a t of r e e f s a l r e a d y du r i n g th e Ki m m e r i d g i a n wa s c a u s e d by t e c t o n i c r e a c t i v a t i o n . Ri f t t e c t o n i c s i n t h e n o r t h e r n A t l a n t i c g r a b e n sy s t e m s a l s o r e s u l t e d i n r e n e w e d t e r r i g e n e o u s se d i m e n t a t i o n a n d u p l i f t s e l s ew h e r e . H o w e v e r , t h i s t e c t o n i c a l l y an d po s s i b l y cl i m a t i c a l l y i n d u c e d ge n e r a l r e t r e a t of r e e f s w a s pu n c t u a t e d by f l o o d i n g ev e n t s of hi g h e r or d e r . I n m a n y ar e a s , t h e s e s h o r t - t e r m e d ev e n t s br o u g h t ba c k ep i s o d i c a l r e e f gr o w t h , pa r t i c u l a r l y du r i n g t h e Hy p s e l o c y c l u m ó D i v i s u m , E u d o x u s , an d Be c k e r i ch r o n s . 3 . 3 . T e c t o n i c Co n t r o l R e e f d e v e l o p r n e n t a l o n g t h e n o r t h e r n T e t h y s sh e l f w a s st r o n g l y c o n t r a s t e d b y t h e p a t t e r n o f r e e f g r o w t h o n t h e s o u t h e r n T e t h y s s h e l f , w h i c h c a n no t b e c o r r e l a t e d w i t h t h e g e n e r a l se a - l e v e l d e v e l o p m e n t . Re e f s a r e m u c h r a r e r , w h i c h i s p a r t i c u l a r l y t r u e o f t h e L a t e Ju r a s s i c , a t l e a s t f o r t h e w e s t e r n p a r t o f t h e T e t h y s . D u r i n g t h e E a r l y J u r a s s i c , r a m p s o r e n e c h e l o n g r a b e n s s t il l e x i s t e d y e t we r e ra r e (S t a n l e y , 19 8 8 ) . Th e y pr o v i d e d en v i r o n m e n t s fo r co r a l an d s p o n g e r e e f d e v e l o p m e n t o n t h e sh a l l o w a n d d e e p e r sh e l f . T e c t o n i c b u t n o t

FIGURE 19. Distribution of Jurassic coral and sponge reefs at both margins of the Tethys. Along the northern Tethys shelf, increasing proliferation of reefs is related largely to the raising sea level, whereas along the southern Tethys shelf, the tectonic style of the shelf determines distribution and frequency of reefs. See text for details. (After Leinfelder, 1994a, modified.)

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c o n t e m p o r a n e o u s dr o w n i n g of ma n y of th e s e a r e a s ma d e th e s e po t e n t i a l r e e f h a b i t a t s d i s a p p e a r d u r i n g t h e E a r l y a n d Mi d - J u r a s s i c . O n l y a t t h e m a r g i n s o f r a r e , s t e e p l y b o u n d , p r o b a b l y t r a n s p r e s s i o n a l h o r s t st r u c t u r e s c o u l d c o r a l r e e f s o c c a s i o n a l l y g r o w s t i l l d u r i n g t h e L a t e Ju r a s s i c ( e . g . P l a s s e n l i m e s t o n e a n d I t a l i a n e x a m p l e s , f o r r e f e r e n c e s se e S e c t i o n 2 . 1 ) . H e n c e , t e c t o n i c i n f l u e n c e o n r e e f d e v e l o p m e n t a n d r e e f d i s t r i b u t i o n i s p a r t i c u l a r l y o b v i o u s o n t h e so u t h e r n T e t h y s sh e l f , b u t a l s o i n t h e L u s i t a n i a n Ba s i n o f c e n t r a l P o r t u g a l w h i c h i s a n A t l a n t i c r i f t ba s i n ( W i l s o n e t al . , 19 8 9 ) . An o t h e r in t e r e s t i n g f e a t u r e is th a t U p p e r J u r a s s i c c o r a l r e e f s o f t h e so u t h e r n T e t h y s sh e l f a p p e a r t o e x h i b i t m u c h l e s s m i c r o b o l i t e cr u s t s an d on l y m o d e r a t e t o l o w di v e r s i t i e s , al t h o u g h de t a i l e d s t u d i e s ar e ne c e s s a r y t o pr o v e t h i s qu a l i t a t i v e i m p r e s s i o n . I f t r u e , t h i s m i g h t b e d u e t o st r o n g l y o l i g o t r o p h i c c o n d i t i o n s , w h i c h d u r i n g t h e Ju r a s s i c d i d n o t y e t al l o w m a x i m u m d i v e r s i t i e s ( s e e S e c t i o n 2. 3 . 1 ) .

4 . Co n c l u s i o n s S t a r t i n g f r o m a l i m i t e d s t o c k o f s u r v i v i n g r e e f f a u n a a f t e r t h e T r i a ss i c / J u r a s s i c m a s s e x t i n c t i o n , Ju r a s s i c r e e f s b e c a m e i n c r e a s i n g l y n u m e r o u s d u r i n g t h e c o u r s e o f t h e J u r a s s i c , a n d re e f s f r o m t h e L a t e J u r a s s i c r e p r e s e n t o n e o f t h e m a j o r p e a k s i n r e e f e v o l u t i o n i n E a r t h h i s t o r y . J u r a s s i c r e e f s w e r e no t y e t a s s p e c i a l i z e d a s m o d e r n r e e f s f o r h i g h l y o l i g o t r o p h i c se t t i n g s b u t i n st e a d c o v e r e d a br o a d ar r a y of re e f a l en v i r o n m e n t s , ra n g i n g f r o m sh a l l o w , hi g h e n e r g y d o w n t o se v e r a l h u n d r e d m e t e r s d e p t h , f r o m z e r o se d i m e n t a t i o n t o c o n s i d e r a b l y e l e v a t e d se d i m e n t a t i o n r a t e s , f r o m f u l l y m a r i n e t o b r a c k i s h , a n d f r o m m i l d l y ol i g o t r o p h i c t o eu t r o p h i c an d e v e n dy s a e r o b i c . Ho w e v e r , t h e s e v e r y d i f f e r e n t se t t i n g s w e r e n o t o c c u p i e d b y o n e si n g l e r e e f t y p e , b u t w e r e c h a r a c t e r i z e d by ve r y di f f e r e n t r e e f t y p e s , wi t h en d m e m b e r gr o u p s co n s i s t i n g o f c o r a l r e e f s , si l i c e o u s sp o n g e r e e f s , a n d p u r e m i c r o b o l i t e r e e f s . T h e m a n y r e e f t y p e s a n d su b t y p e s w e r e n o t o n l y st a t i c a l l y r e l a t e d t o t h e e x i s t e n c e o f d i s t i n c t en v i r o n m e n t s , bu t co u l d al s o r e s p o n d , an d t o s o m e de g r e e a d a p t t h e m s e l v e s , t o e n v i r o n m e n t a l c h a n g e . Be s i d e s se d i m e n t o l o g i c a l a n a l y s i s , i t i s , s p e c i f i c a l l y , t h e i n t e r p r e t a t i o n o f p h y s i o l o g i c a l a b i l i t i e s o f Ju r a s s i c r e e f o r g a n i s m s b y c o n s t r u c t i o n a l m o r p h o l o g i c a n a l y s i s a n d se m i q u a n t i t a t i v e t o q u a n t i t a t i v e a s s e s s m e n t s o f t h e t r o p h i c a n d d i v e r s i t y s t r u c t u r e o f re e f a s s o c i a t i o n s w h i c h a l l o w s su c h c o n c l u s i o n s . T h i s m a k e s J u r a s s i c r e e f s a mo s t va l u a b l e to o l f o r pa l e o e n v i r o n m e n t a l , i n c l u d i n g p a l e o c l i m a t i c , p a l e o o c e a n o g r a p h i c , se a - l e v e l a s w e l l a s p a l e o s t r u c t u r a l a n a l y s i s . A p a r t i c u l a r f e a t u r e i n Ju r a s s i c r e e f a n a l y s i s i s t h e p o s s i b i l i t y o f d e t e c t i n g eu t r o p h i c an d dy s a e r o b i c ep i s o d e s f r o m de v e l o p m e n t of pu r e m i c r o b o l i t e s i n r e g i m e s o f st r o n g l y r e d u c e d se d i m e n t a t i o n , w h i c h n o r m a l l y p r e v e n t s d e v e l o p m e n t o f b l a c k sh a l e s . L a t e r a l a r r a n g e m e n t o f c o e v a l , b u t d i f f e r e n t r e e f t y p e s a l l o w s f o r i n t e r p r e t a t i o n o f g e n e r a l sh e l f t y p e a s w e l l a s sm a l l - s c a l e d i f f e r e n c e s o f su b m a r i n e m o r p h o l o g y . T h e d e v e l o p m e n t o f c l a s s i c a l s po n g e m o u n d s wa s pa r t i c u l a r l y ch a r a c t e r i s t i c f o r ho m o c l i n a l o u t e r r a m p s , w h e r e a s

300

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c o r a l - s i l i c e o u s sp o n g e ó m i c r o b o l i t e r e e f s m a y b e c h a r a c t e r i s t i c f o r st e e p e n e d s l o p e s . Re e f s o f t h e co r a l ó d e b r i s t y p e ar e l a r g e l y r e s t r i c t e d t o f i a t r a m p s o r at t h e sh a l l o w sh e l f b r e a k o f m i l d l y i n c l i n e d d e p o s i t i o n a l m a r g i n s . T h e s e d e b r i s p i l e r e e f s ex p r e s s pr o b l e m s wi t h t h e l a r g e am o u n t s of c a l c i c l a s t i c m a t e r i a l p r o d u c e d by wa v e ac t i o n an d bi o e r o s i o n ( L e i n f e l d e r , 19 9 2 ) . T h i s m a k e s t h e m p e r f e c t t a r g e t s f o r oi l ex p l o r a t i o n pr o v i d e d pr i m a r y po r o s i t y i s pa r t i a l l y p r e s e r v e d o r se c o n d a r y v u g g y l e a c h i n g p o r o s i t y d e v e l o p e d . I f d e v e l o p i n g a l o n g a sh e l f b r e a k i n d i r e c t p r o x i m i t y o f a st e e p b y p a s s m a r g i n , h i g h- e n e r g y c o r a l - d e b r i s r e e f s ca n ex p o r t l a r g e am o u n t s of ge n e r a t e d ca l c i c l a s t i c m a t e r i a l , w h i c h e n a b l e s m i c r o b i a l m a t s t o st a b i l i z e t h e r e m a i n d e r o f t h e d e b r i s . T h i s g i v e s r i s e t o ea s i l y r e c o g n i z a b l e co r a l ó m i c r o b o l i t e ó d e b r i s r e e f s ( L e i n f e l d e r , 1992). A n i m p o r t a n t t h e m e i s t h e r e s t r i c t i o n o r p r o l i f e r a t i o n o f r e e f s d u r i n g se a l e v e l c h a n g e . Ma j o r r e e f e p i s o d e s a r e c o r r e l a t e d w i t h t h i r d - o r d e r r is e s a n d h i g h s t a n d s , bu t i n d i v i d u a l r e e f s no r m a l l y g r e w du r i n g f o r t h , f i f t h , or ev e n h i g h e r o r d e r . T h i s i s p a r t i c u l a r l y t r u e o f c o r a l r e e f s o n t e r r i g e n e o us l y i n f l u e n c e d r a m p s . S p o n g e m o u n d s m a y sh o w c o m p o s i t e , c l u s t e r - t y p e a r c h i t e c t u r e , w i t h i n d i v i d u a l , st a c k e d r e e f b o d i e s a l s o b e i n g r e l a t e d t o f o u r t h - a n d f i f t h - o r d e r f i o o d i n g s or ea r l y hi g h s t a n d s . I n c o m p a r i n g t h e st r u c t u r e o f m o d e r n a n d Ju r a s s i c r e e f s , si m i l a r i t i e s a n d d i f f e r e n c e s e x i s t . T h e c a l c a r e o u s si l i c e o u s sp o n g e ó m i c r o b o l i t e m u d m o u n d s o f Ju r a s s i c t i m e t o t h e p r e s e n t k n o w l e d g e a r e u n p a r a l l e l e d b y m o d e r n a n a l o g u e s , a l t h o u g h so m e si l i c i c l a s t i c c o l d - w a t e r sp o n g e ó m i c r o b i a l m a t s o r m o u n d s a n d so m e t r o p i c a l d e e p - w a t e r l i t h i s t i d a s s o c i a t i o n s sh a r e c e r t a i n s i m i l a r i t i e s . W i t h i n t h e Ju r a s s i c sp o n g e f a c i e s , a w i d e v a r i e t y o f t y p e s a n d s e t t i n g s oc c u r r e d . E n v i r o n m e n t a l pa r a m e t e r s f o r t h e s e r e e f s ar e r e s o l v e d by a c o m b i n e d a p p r o a c h o f p a l e o e c o l o g i c a l a n d se d i m e n t o l o g i c a l a n a l y s i s . T h e c o n t r o v e r s i a l b a t h y m e t r y o f Ju r a s s i c si l i c e o u s sp o n g e r e e f s i s p a r t l y c a u s e d b y t h e l a c k o f d i f f e r e n t i a t i n g s p o n g e r e e f t y p e s . L i t h i s t i d - d o m i n a t e d re e f s w e r e g e n e r a l l y b u t n o t n e c e s s a r i l y m o r e sh a l l o w t h a n h e x a c t i n e l l i d - d o m i n a t e d r e e f s . S i l i c e o u s sp o n g e r e e f s c a n b e t r a n s i t i o n a l w i t h t h e l o w e r p a r t o f t h e c o r a l r e e f z o n e , b u t ar e no r m a l l y be l o w th e co r a l re e f zo n e an d po s s i b l y de e p e r th a n a b o u t 5 0 m . T h e l o w e r d i s t r i b u t i o n b o u n d a r y o f h e x a c t i n o s a n r e e f s m i gh t we l l b e do w n to mo r e th a n 10 0 m, wi t h th e lo w e r li m i t pr o b a b l y de f i n e d b y th e e x i s t e n c e o f o x y g e n - d e p l e t e d b o t t o m w a t e r s o r se d i m e n t a c c u m u l a t i o n s . T h e w i d e d i s t r i b u t i o n o f U p p e r Ju r a s s i c sp o n g e r e e f s e s p e c i a l l y a l o n g t h e n o r t h e r n T e t h y s s h e l f s e a s i s a r e f l e c t i o n o f t h e h i g h s e a l e v e l . M o d e r n s h e l v es a r e r u g g e d i n t h e p r e f e r r e d d e p t h z o n e o f Ju r a s s i c sp o n g e r e e f g r o w t h , d u e t o g l a c i a l se a - l e v e l f l u c t u a t i o n s t h a t m a k e t h e e n v i r o n m e n t t o o v a r i a b l e f o r t h e d e v e l o p m e n t o f sp o n g e m o u n d s . A l s o , t h e l o w s e a - l e v e l o f t o d a y c a u s e s s t r o n g e r te r r i g e n e o u s in f l u x , w h i c h ma y by p a s s sh a l l o w - w a t e r co r a l re e f s bu t m a y su p p r e s s r e e f g r o w t h i n t h e d e e p e r w a t e r . C o r a l r e e f s a n d p u r e m i c r o b o l i t e r e e f s e x i s t e d b o t h d u r i n g t h e J u r a s si c a n d t o d a y . Ju s t l i k e t h e i r Ju r a s s i c c o u n t e r p a r t s , m o d e r n m i c r o b o l i t e r e e f s a r e r e s t r i c t e d t o e x t r e m e se t t i n g s , su c h a s h y p e r s a l i n e , i n t e r t i d a l , o r f r e s h w a t e r p o n d s o r h i g h l y a b r a s i v e se t t i n g s . H o w e v e r , t h e e u t r o p h i c ó d y s a e r o b i c p u r e

301

Ju ra ssi c Re e f Ec o sy ste m s

temperature 18

terrigenous N aC influx l

salinity 22

36 °C

25-29

40 %o

25-35

TROPICAL / SUBTROPICAL REEFS strong oligotrophy

nutrients

optimum reefs coral-algal reefs

‘stressed‘ reefs

nut

Halimeda algal‘mounds‘

photic aphotic

rien

ts

nutrient-rich DEEP-WATER MOUNDS

The modern ‘Reef Windows’

152 - 139 mio. years el

elevated terrigenous influx

ev

at

ed

nu

tri

marine

brackish en

ts

marly coral meadows marly coralmicrobial reefs

optim

um re

efs

fluctuating nutrients warm tropical water cool water?

sponge siliceous sponge meadows coral microbial mounds reefs and coral debris reefs pure microbolite oxygen- nutrientreefs deficient deficient

The ‘Reef Window’ of the Late Jurassic

water

water

FIGURE 20. The Upper Jurassic and the modern ,,reef windows,ì showing generalized reef types and their environmental conditions. (Modern window after James and Bourque, 1992, modifled). Note that the Upper Jurassic reef window was much larger than the modern tropicalósubtropical one, due to both better habitat availability (higher sea level) and lesser specialization or reefs. Deep-water coral mounds also are present in modern settings but occur in a distinct window separated from the tropicalósubtropical reef window. The optimum for Upper Jurassic coral reefs (as reflected by maximum diversities and pronounced reef growth) was slightly deeper and closer to coastlines than for modern coral reefs. (After Leinfelder and Nose, 1999.)

m i c r o b o l i t e ty p e of Ea r l y an d L a t e Ju r a s s i c of so u t h w e s t Eu r o p e an d th e A t l a n t i c h a s n o d i r e c t m o d e r n c o u n t e r p a r t , sa v e f o r t h e m i c r o b o l i t e r e e f s o f s o m e h y p e r a l k a l i n e l a k e s w i t h a n o x i c b o t t o m w a t e r s su c h a s t h e S a t o n d a L a k e ( K e m p e an d Ka z m i e r c z a k , 19 9 3 ) . T h e f a i r l y f r e q u e n t oc c u r r e n c e of pu r e m i c r o b o l i t e r e e f s , p a r t i c u l a r l y d u r i n g so m e t i m e e p i s o d e s o f t h e L a t e Ju r a s s i c , i s an e x p r e s s i o n of t h e gr e e n h o u s e - t y p e cl i m a t e of t h a t t i m e , ca u s i n g t e m p o r

302

Ch a p te r 8

a r y c o l l a p s e o f sh e l f w a t e r c i r c u l a t i o n , a p r o c e s s t h a t i s o n l y k n o w n t o d a y a s a n e f f e c t o f h o t su m m e r s i n v e r y m a r g i n a l s e a s su c h a s t h e N o r t h S e a o r t h e A d r i a t i c S e a . Ju r a s s i c c o r a l r e e f s w e r e n e a r l y a s c o m p l e x a s m o d e r n r e e f s , b u t l a c k e d o n e p a r t i c u l a r e l e m e n t : t h e c o r a l l i n e r e d a l g a e ( L e i n f e l d e r an d N o s e , 1 99 9 ). Th e se al g ae ar e es pe c ia l ly im p or t an t in Ca ri b be a n and At l an t ic re e fs bu t a l s o a r e a p r o m i n e n t f e a t u r e i n I n d o p a c i f i c r e e f s . Mi c r o b o l i t e s c o u l d a n t i c i p a t e b i n d i n g a n d c o n s t r u c t i o n i n Ju r a s s i c r e e f s a s p e r f o r m e d b y m o d e r n c o r a l ó r e d a l g a l r e e f s , bu t th e y no r m a l l y we r e un a b l e to de v e l o p i n t o th e ve r y hi g h e n e r g y z o n e , g i v i n g Ju r a s s i c w i n d w a r d sh a l l o w - w a t e r r e e f s a d i s t i n c t d e b r i s p i l e a s p e c t . A l s o , c o r a l s g r e w m o r e s l o w l y t h a n t o d a y , p r o b a b l y b e c a us e t h e p h o t o s y m b i o t i c r e l a t i o n , t h o u g h ex i s t i n g , w a s no t ye t a s f l e x i b l e a n d ef f e c t i v e . M a n y Ju r a s s i c p h o t o s y m b i o t i c c o r a l s w e r e a p p a r e n t l y st i l l m o r e d e p e n d e n t o n h e t e r o t r o p h i c n u t r i t i o n . Co n s e q u e n t l y , Ju r a s s i c c o r a l r e e f s a r e m o r e f r e q u e n t l y f o u n d i n t e r r i g e n e o u s l y i n f l u e n c e d , m e s o t r o p h i c se t t i n g s t h a n t o d a y ( F i g . 2 0 ) . A C K N O W L E D G M E N T S : T h i s ch a p t e r b e n e f i t e d f r o m f r u i t f u l d i s c u s s i o n s w i t h m a n y co l l e a g u e s , es p e c i a l l y wi t h i n m y ow n wo r k i n g gr o u p : I n pa r t i c u l a r I o w e t h a n k s t o Ma r t i n N o s e ( M u n i c h ) , Ma n f r e d K r a u t t e r ( S t u t t g a r t ) , D i e t e r S c h m i d ( M u n i c h ) , W i n f r i e d W e r n e r ( M u n i c h ) , a n d Ma r t i n T a k a c s ( S t u t t g a r t ) . G e o r g e S t a n l e y , Jr . , a n d Je a n n e t t e Y a r n e l l a r e t h a n k e d f o r c r i t i c a l l y c o m m e n t i n g on an ea r l y dr a f t of t h i s ch a p t e r an d f o r i m p r o v i n g m y E n g l i s h . L o n g - t e r m f i n a n c i a l su p p o r t b y t h e G e r m a n R e s e a r c h F o u n d a t i o n ( D F G p r o j e c t L e 58 0 / 4 ) i s gr a t e f u l l y a c k n o w l e d g e d .

Referen ces Ali, 0. E., 1983, Microsolenid corals as rock-formers in the Corallian (Upper Jurassic) rocks of England, Geol. Mag. 120:375ó380. Allison, N., Tudhope, A. W., and Fallick, A. E., 1996, Factors influencing the stable carbon and oxygen isotopic composition of Porites lutea coral skeletons from Phuket, South Thailand, Coral Reefs 15:43ó57. Aurell, M., and B·denas, B., 1997, The pinnacle reefs of Jabaloyas (Late Kimmeridgian, NE Spain, Vertical zonation and associated facies related to sea level changes, Cuad. Geol. Ibérica, 22:37ó64. Baria, L. R., Stoudt, D. L., Harris, P. M., and d, P. D., 1982, Upper Jurassic reefs of Smackover Formation, United States GuIf Coast, Am. Assoc. Petrol. Geol. Bull. 66:1449ó1482. Baumeister, J., 1997, Funktionsmorphologie und Pal‰oˆkologie regul‰rer jurassischer Echinoiden des nordwestlichen Tethys-Schelfs, unpublished dissertation (Dr. rer. nat.), Faculty of Geoand Biosciences, University of Stuttgart. Baumeister, J. G., and Leinfelder, R. R., 1998, Constructional morphology of three Upper Jurassic echinoids, Paloeontology 42(2):203ó2 19. Baumg‰rtner. M., and Reyle, M., 1995, Oberjurassische Rampenentwicklung in der Region von Jabaloyas und Arroyo Cerezo (Keltiberikum; Spanien), Profil 6:339ó361. Bertling, M., 1993, Ecology and distribution of the Late Jurassic Scleractinian Thamnasteria concinna (Goldfuss) in Europe, Paloeogeogr. Paloeocliniatol. Paloeoecol. 105:311ó335. Bertling, M., 1997a, Bioerosion of Late Jurassic reef coralsóImplications for reef evolution, Proc. 8th Int. Coral Reef Sym. 2:1663ó1668.

Ju ra ssi c Re e f Ec o sy ste m s

303

Bertling, M., 1997b, Structure and function of coral associations under extreme siltation stressóA case study from the northern German Upper Jurassic, Proc. 8th Int. Coral Reef Sym., 2:1749 -1754. Brachert, T., 1992, Sequence stratigraphy and paleo-oceanography of an open-marine mixed carbonate/siliciclastic succession, Late Jurassic; South Germany, Facies 27:179ó216. Buddemeier, R. W., and Kinzie, R. A., 1976, Coral growth, Oceonogr. Mar. Biol. Annu. Rev. 14:183ó225. Coates, G. A., and Jackson, J. B. C., 1987, Clonal growth, algal symbiosis, and reef formation by corals, Paleobiology 13: 363ó378. Conway, K. W., and Barrie, J. V., 1997, Modern Hexactinellid sponge reefs on the western Canadian continental margin, l8th lAS Reg. Europ. Meeting, Heidelberg, 1997, Abstracts, G a e a heidelbergensis 3:105. Conway, K. W., Barrie, J. V., Austin, W. C., and Luternauer, J. L., 1991, Holocene sponge bioherms on the western Canadian continental shelf, Continenta1 Shelf Res. 11: 771ó790. Crevello, P., and Harns, P., 1984, Depositional models for Jurassic reefal buildups, in: The Jurassic of the Gulf Rim (W. P. S. Ventress, D. G. Bebout, B. F. Perkins, and C. H. Moore, eds.), SEPM GuIf Coast Section, Proceedings of the 3rd Annual Research Conference, Tulsa, OK, pp. 57ó 102. Dayton, P. K., Mordida, B. J., and Bacon, F., 1994, Polar marine communities, Am. Zool. 34:90ó99. Deusch, M., Friebe, A., and Krautter, M. 1991, Spongiolithic facies in the Middle and Upper Jurassic of Spain, in: Fossil and Recent Sponges (J. Reitner and H. Keupp, eds.), Springer, New York, pp. 498ó505. Dietl, G., Dietl, 0., Kapitzke, M., Rieter, M., Schweigert, G., Ilg, A., and Hugger, R., 1996, Der Nusplinger Plattenkalk (Weifler Jura)óGrabungskampagne 1996, Jh. Ges. Naturk.. Württemberg 153:185ó203. Helm, C., 1997, Faunistische Untersuchungen an einem Fleckenriff des Oberjura (florigemmaBank; S¸ntel, unpublished diploma Thesis, Fachbereich Geowissenschaften, University of Hannover. Draganescu, A., 1976, Constructional to corpuscular spongeóalgal, algal and coralalgal facies in the Upper Jurassic carbonate formation of central Dobrogea (the Casimcea Formation), in: Carbonate Rocks ond Evaporites (D. Patrullius et al., eds.), Internat. Coll. Carb. Rocks/Evapor. Roumania, Guidebook Series, Vol. 15, pp. 3ó43. Dromart, G., Gaillard, C., and Jansa, L. F., 1994, Deep-marine microbial structures in the Upper Jurassic of Western Tethys, in: Phanerozoic Stromotolites II (J. Bertrand-Sarfati and C. Monty, eds.), Kluwer, Dordrecht, pp. 295ó318. Duarte, L. V., and Krautter, M., 1998, Siliceous sponge mud mounds from the Toarcian of the Lusitanian Basin, Portugal: Facies, stratigraphy and sequential evolution, Abstr. Jurassic Symposium, Vancouver, 1998. Ellis, P. M., Wilson, R. C. L., and Leinfelder, R. R., 1990, Controls on Upper Jurassic carbonate buildup development in the Lusitanian Basin, Portugal, in: Carbonate Platforms. Facies, Sequences and Evolution (M. E. Tucker, J. L. Wilson, P. D. Crevello, J. R. Sarg, and J. F. Read, eds.), Int. Assoc. Sediment. Spec. Publ. 9:169ó202. Elmi, 5., 1987, Le Jurassique infÈrieur du Bas Vivarais (sud-est) de la France (avec la collaboration de R. Mouterde, C. Ruget, Y. Almeras, and G. Naud), 2iËme Colloqu. Centr. Internat. Etudes du Lias (C.l.E.L.), Lyon, 27ó3t) Mai 1986, Cah. Inst. Cathol.. Lyon Sér. Sci. 1:63ó189. Errenst, C., 1990a, Das korallenf¸hrende Kimmeridgium der nordwestlichen Iberischen Ketten und angrenzender Gebiete (Fazies, Pal‰ogeographie und Beschreibung der Korallenfauna), Teil 1, Polaeontographica Abt. A 214:121ó207. Errenst, C., 1990b, Das korallenf¸hrende Kimmeridgium der nordwestlichen Iberischen Ketten und angrenzender Gebiete (Fazies, Pal‰ogeographie und Beschreibung der Korallenfauna), Teil 2, Palaeontograhica Abt. A 215:1ó42. Fagerstrom, J. A., 1987, The Evolution of Reef Communities, Wiley, New York. Fezer, R., 1988, Die oberjurassische karbonatische Regressionsfazies im s¸dwestlichen Keltiberikum zwischen Griegos und Aras de Alpuente (Prov. Teruel, Cuenca, Valencia; Spanien), Arb. Inst. Geol. Paläont.. Univ. Stuttgart N.F. 84:1ó119.

304

Ch a p te r 8

Fl¸gel, E., Alt, T., Joachimski, M., Riemann, V., and Scheller, J., 1993. Korallen-Kalke im oberen MaIm (Unter-Tithon) der S¸dlichen Frankenalb (Laisacker, Marching. Mikrofazies-Merkmale und Fazies-Interpretation, Geo. Bl. NO-Bayern 43:33ó56. F¸rsich, F. T., 1981, Salinity-controlled benthic associations from the Upper Jurassic of Portugal, Lethaia 14:203ó223. F¸rsich, F. T., and Werner, W., 1986, Benthic associations and their environmental significance in the Lusitanian Basin (Upper Jurassic, Portugal), N. Jb. Geol. Palaont. Abh. 172:271ó329. F¸rsich, F. T., and Werner, W., 1991, Palaeoecology of coralline spongeócoral meadows from the Upper Jurassic of Portugal, Paläont. Z. 65:35ó69. Gaillard, C., 1983, Les biohermes ‡ spongiaires et leur environnement dans lëOxfordien du Jura mÈridional, Docum. Lab. Géol. Lyon 90:1ó515. Geister, J., 1983, Holoz‰ne westindische Korallenriffe: Geomorphologie, ÷kologie und Fazies, Facies 9:173ó284. Geister, J., 1992, Modern reef development and Cenozoic evolution of an oceanic island/reef complex: Isla de Providencia (Western Carribean Sea, Colombia), Facies 27:1ó70. Geister, J., and LathuiliËre, B., 1991, Jurassic coral reefs of the northeastern Paris basin (Luxembourg and Lorraine), Excursion A 3, Excursion-Guidebook, VI. Int. Sympos. on Fossil Cnidaria, M¸nster. Ginsburg, R. N., 1997, Coral reefs are cities under the sea. Transparencies and teachers notes to introduce coral reefs to students and adults, (manuscript), Project Miami RARE., The Hachette Filipacchi Foundation. Greb, L., Saric, B., Seyfried, H., Broszonn, T., Brauch, 5., Gugau, G., Wiltschko, C., and Leinfelder, R., 1996, ÷kologie und Sedimentologie eines rezenten Rampensystems an der Karibikk¸ste von Panam·, Profil 10:1ó168. Gwinner, M. P., 1976, Origin of the Upper Jurassic limestones of the Swabian Alb (Southwest Germany), Contr. Sedimentol. 5:1ó75. Gygi, R. A., and Persoz, F. 1986, Mineralostratigraphy, litho- and biostratigraphy combined in correlation of the Oxfordian of the Swiss Jura range, Eclogae geol. Helv. 79:455ó491. Hantzpergue, P., 1988, Les Plates-Formes Recifales du Jurassique Nord-Aquitain. Livret-Guide Excursion GFEJ, Poitiers. Haq, B. U., Hardenbol, J., and Vail, P. R., 1988, Mesozoic and Cenozoic chronostratigraphy and cycles of sea level change, SEPM, Spec. Publ. 42:71ó108. Henrich, R., Hartmann, M., Reitner, J., Sch‰fer, P., Freiwald, A., Steinmetz, S., Dietrich, P., and Thiede, J.. 1992, Facies belts and communities of the Arctic Vesterisbanken Seamount (Central Greenland Sea), Facies 27:71ó104. Henrich, R., Freiwald, A., Wahrmann, A., Sch‰fer, P., Samtleben, C., and Zankl, H., 1996, Nordic coldwater carbonates: Occurrences and controls, in: Global and Regional Controls on Biogenic Sedimentation.I. Reef Evolution (J. Reitner, F. Neuweilar, and F. Gunkel, eds.), research reports. Göttinger Arb. Geol. Palaeont. Sb 2: 35ó52. Herrmann, R., 1996, Entwicklung einer oberjurassischen Karbonatplattform: Biofazies, Riffe und Sedimentologie im Oxfordium der Zentralen Dobrogea (Ost-Rum‰nien), Berliner geowiss. Abb. E 19:1ó101. Highsmith. R. C.. 1979, Coral growth rates and the environmental control of density banding, J. Exp. Mar. Biol. Ecol. 37:105ó125. Hobbie, J. E., Holm-Hansen, 0., Packard, T. T., Pomeroy, L. R., Sheldon, R. W., Homas, J. P. and Wiebe, W. J., 1972, A study of the distribution and activity of microorganisms in the ocean water, Limnol. Oceanogr. 17:544ó555. Hubbard, J. A., and Pocock, Y. P., 1972, Sediment rejection by scleractinian corals: a key to palaeoenvironmental reconstruction, Geol.Rundschau 61:598ó626. Insalaco, E., 1996a, Upper Jurassic microsolenid biostromes of northern and central Europe: Facies and depositional environment, Palaeogeogr. Palaeoclimatol. Palaeoecol. 121:169ó194. lnsalaco, E., 1996b, The use of Late Jurassic coral growth bands as palaeoenvironmental indicators, Palaeontology 39:413ó431. Insalaco, E., Hallam, A., and Rosen, B., 1997, Oxfordian (Upper Jurassic) coral reefs in Western Europe: Reef types and conceptual depositional model, Sedimentology 44:707ó734.

Jurassic Reef Ecosystems

305

James, N. P., 1983, Reef environments, in: Carbonate Depositional Environments (P.A. Scholle, D. G. Bebout, and C. H. Moore, eds.), Am. Assoc. Petrol. Geol., Mem. 33:345ó440. James, N. P., and Bourque. P., 1992, Reefs and mounds, in: Facies Models. Response to Sea Level Change (R. G. Walker and N. P. James, eds.), Geological Association of Canada, Waterloo, pp. 323ó347. Jansa, L. F., Pratt, B. R., and Dromart, G., 1989, Deep water thrombolite mounds from the Upper Jurassic of offshore Nova Scotia, in: Reefs, Canada and Adjacent Areas (H. H. J. Geldsetzer, N. P. James, and G. E. Tebbutt, eds.), Can. Soc. Petroleum Geol. Mem. 13:725ó735. Kauffman, E. G., and Scott, R. W., 1976, Basic concepts of community ecology and paleoecology, in: Structure and Classification of Paleocommunities (R. W. Scott and R. R. West, eds.), Dowden, Hutchinson, and Ross, Stroudsburg, pp. 1ó28. Kempe, S., 1990, Alkalinity: The link between anaerobic basins and shallow water carbonates? Naturwissenschaften 77:426ó427. Kempe, S., and Kazmierczak, J., 1993, Satonda Grater Lake, Indonesia: Hydrogeochemsistry and biocarbonates, Facies 29:1ó32. Kempe, S, and Kazinierczak, J., 1994, The role of alkalinity in the evolution of ocean chemistry, organisation of living systems and biocalcification processes, in: Past and Present Biomineralization Processes. Considerations about the Carbonate Cycle (F. Doumenge, ed.), IUCN-COE Workshop, Monaco, 1993, Bull. Inst. Oceanogr. Monaco No. Spéc. 13:61ó117. Kempe, S., Kazmierczak, J., Reimer, A., Landmann, G., and Reitner, J., 1996, Microbialites and hydrochemistry of the Crater Lake of Satondaóa status report, in: Global and Regional Controls on Biogenic Sedimentation. 1. Reef Evolution. Research Reports (J. Reitner, F. Neuweiler, and F. Gunkel, eds.), Göttinger Arb. Geol. Paläont. Sb2:59ó63. Keupp, H., Brugger, H., Galling. U., Hefter, J., Herrmann, R., Jenisch, A., Kempe, S.. Michaelis, W., Seifert, R., and Thiel, V., 1990, Paleobiological controls of Jurassic spongiolites, in: Global and Regional Controls on Biogenic Sedimentation. 1. Reef Evolution. Research Reports (J. Reitner, F. Neuweiler, and F. Gunkel, eds.), Göttinger Arb. Geol. Paläont. Sb2:209ó214. Koch, R., 1996, Paleogeography, microfacies and diagenesis of Upper Jurassic (Malm) "Reef"limestones in the Geislingen-Eybtal area (Swabian Alb), in: Global and Regional Controls on Biogenic Sedimentation. 1. Reef Evolution. Research Reports (J, Reitner, F. Neuweiler, and F. Gunkel, eds.), Göttinger Arb. Geol. Paläont. Sb2:215ó220. Koch, R., Senowbari-Daryan, B., and Strauss, H., 1994, The Late Jurassic Massenkalk Fazies of Southern Germany: Calcareous sand piles rather than organic reefs, Facies 31:179ó208. Krautter, M., 1994, Observations on Eudea clavata Lamouroux (Calcarea) from the Upper Jurassic of Portugal, in: Proceedings of the 4th International Porifera Gongress ,Sponges in Time and Space“ Amsterdam 1993 (R. W. M. van Soest, T. M. G. van Kempen, and J. C. Braekman, eds.), Balkema, Amsterdam, pp. 29ó34. Krautter, M., 1995, Kieselschw‰mme als potentielle Indikatoren f¸r Sedimentationsrate und N‰hrstoffangebot am Beispiel der Oxford-Schwammkalke von Spanien, Profil 8:281ó304. Krautter, M., 1996, Kieselschw‰mme aus dem unterjurassischen Misonekalk der Trento-Plattform (S¸dalpen, Taxonomie und phylogenetische Relevanz, Paläont. Z. 70:301ó313. Krautter, M., 1997, Aspekte zur Pal‰¸kologie postpal‰ozoischer Kieselschw‰mme, Profil 11:199ó 324. Laternser, R., 2000, Oberjurassische Korallenriffe von Nordostfrankreich (Lothringen) und S¸dwestdeutschland — unpublished dissertation, University of Stuttgart. Le„o, Z. M. A. N., and Ginsburg, R. N., 1997, Living reefs surrounded by siliciclastic sediments: The Abrolhos coastal reefs, Bahia, Brazil, Proc. 8th Int. Coral Reef Sym. 2:1767ó1772. Legarreta, L., 1991, Evolution of a CallovianóOxfordian carbonate margin in the NeuquÈn Basin of west-central Argentina: Facies, architecture, depositional sequences and global sea-level changes, Sediment. Geol. 70:209ó240. Leinfelder, R. R., 1986, Facies, stratigraphy and paleogeographic analysis ofUpper? Kimmeridgian to Upper Portlandian sediments in the environs of Arruda dos Vinhos, Estremadura, Portugal, Münchn. Geowiss. Abh. A7:1ó215. Leinfelder, R. R., 1992, A modern-type Kimmeridgian reef (Ota Limestone, Portugal, Implications for Jurassic reef models, Facies 26:11ó34.

306

Chapter 8

Leinfelder, R. R., 1993a, Upper Jurassic reef types and controlling factors.óA preliminary report, Profil 5:1ó45. Leinfelder, R. R., 1993b, A sequence stratigraphic approach to the Upper Jurassic mixed carbonateósiliciclastic succession of the central Lusitanian Basin, Portugal, Profil 5:119ó140. Leinfelder, R. R., 1994a, Distribution of Jurassic reef types: A mirror of structural and environmental changes during breakup of Pangea, in: Pangea: Global Environments and Resources (B. Beauchamp, A. F. Embry, and D. Glass, eds.), Can. Soc. Petrol. Geol. Mem. 17:677ó700. Leinfelder, R. R., 1994b, Karhonatplattformen und Korallenriffe innerhalb siliziklastischer Sedimentationsbereiche (Oberjura, Lusitanisches Becken, Portugal). Profil 6:1ó207. Leinfelder, R. R., 1997, Coral reefs and carbonate platforms within a siliciclastic setting: General aspects and examples from the Late Jurassic of Portugal: Proc. 8th Int. Coral Reef Sym, Panama City, V.Z., p. 1737ó1742, Smithsonian Tropical Research Institute, Balboa, Panama. Leinfelder, R. R., and Ginsburg, R. N., 1998, St‰dte unter WasseróGibt es so etwas? in: Riffe—Ein faszinierendes Thema für den Schulunterricht. Materialien für die Fächer Biologie, Erdkunde und Geologie (R. R. Leinfelder, U. Kull, and F. Br¸mmer, eds.), Profil 13:105ó116. Leinfelder, R. R., and Keupp, H., 1995, Upper Jurassic mud mounds: Allochthonous sedimentation versus autochthonous carbonate production, in: Mud Mounds: A Polygenetic Spectrum of Finegrained Carbonate Buildups (J. Reitner and F. Neuweiler, coord.), Facies 32:17ó26. Leinfelder, R. R., and Nose, M., 1999, Increasing complexityódecreasing flexibility. A different perspective of reef evolution through time, Profil 17:135ó147. Leinfelder, R. R., and Nose, M., submitted for publication, Physical and geological controls of Upper Jurassic reef growth, in: Reef Systems in Earth History (E. Fl¸gel and H. Zankl, eds.), Springer. HeidelbergóBerlin. Leinfelder, R. R., and Schmid, D. U., 2000, Mesozoic reefal thrombolites and other microbolites, in: Microbial Sediments (R. Riding, ed.), Springer, Berlin, pp. 289ó294. Leinfelder, R. R., and Werner, W., 1993, The systematic position and palaeoecology of the alga Marinella lugeoni Pfender, Zitteliana 20:105ó122. Leinfelder, R. R., and Wilson, R. C. L., 1989, Seismic and sedimentologic features of Oxfordianó Kimmeridgian syn-rift sediments at the eastern margin of the Lusitanian Basin, Portugal, Geol. Rundschau 78:81ó104. Leinfelder, R. R., and Wilson, R. C. L., 1998, Third- order sequences in an Upper Jurassic rift-related second-order sequence, central Lusitanian Basin, Portugal, in: Mesozoic and Cenozoic Sequence Stratigraphy of European Basins (P--C. de Graciansky, J. Hardenbol, T. Jacquin, and P. R. Vail, eds.), SEPM Spec. Publ. Vol. 60, pp. 507ó525. Leinfelder, R. R., Krautter, M., Nose, M., Ramalho, M. M., and Werner, W., 1993a, Siliceous sponge facies from the Upper Jurassic of Portugal, N. Jb. Geol. Paläont. Abh. 189:199ó254. Leinfelder, R. R., Nose, M., Schmid, D. U., and Werner, W., 1993b, Microbial crusts of the Late Jurassic: Composition, palaeoecological significance and importance in reef construction, Facies 29:195ó230. Leinfelder, R. R., Krautter, M., Laternser, R., Nose, M., Schmid, D. U., Schweigert, G., Werner, W., Keupp, H., Brugger, H., Herrmann, R., Rehfeld-Kiefer, U., Schroeder, J. H., Reinhold, C., Koch, R., Zeiss, A., Schweizer, V., Christmann, H., Menges, G., and Luterbacher, H., 1994, The origin of Jurassic reefs: Current research developments and results, Facies 31:1ó56. Leinfelder, R. R., Werner, W., Nose, M., Schmid, D. U., Krautter, M., Laternser, R., Takacs, M., and Hartmann, D., 1996, Palaeoecology, growth parameters and dynamics of coral, sponge and microbolite reefs from the Late Jurassic in: Global and Regional Controls on Biogenic Sedimentation. 1. Reef Evolution. Research Reports (J. Reitner, F. Neuweiler, and F. Gunkel, eds.), GöttingerArb. Geol. Paläont. Sb2:227ó248. LÈvi, C., and LÈvi, P., 1988, Nouveaux spongiaire Lithistides bathyaux ‡ affinitÈs crÈtacÈes de la Nouvelle CaIÈdonie, Bull. Mus. Nat. d‘Histoire Naturelle Paris 10(A2):241ó263. Mackie, G. 0., Lawn, 1. D., and Pavans de Ceccatty, M., 1983, Studies on hexactinellid sponges. II. Excitability, conduction and coordination of responses in Rhabdocalyptus dawsoni (Lambe, 1873), Phil. Trans. Royal Soc. London B Biol. Sci. 301:401ó418.

Jurassic Reef Ecosystems

307

Matheos, S. D.,and Morsch, S M., 1990, Geochemistry and paleoecological aspects of coralbearing limestones from the late Jurassic at the southern end of the Sierra da la Vaca Muerta, NenquÈn Basin, Argentina. N.Jb. Geol. Polöont. Abh. 181:159ó169. Matyszkiewicz, J., 1996, The significance of Saccocomaócalciturbidites for the analysis of the Polish epicontinental Late Jurassic basin: an example from the southern CracowóWielun Upland. Poland), Facies 34:23 40. Matyszkiewicz, J., 1997, Microfacies, sedimentation and some aspects of diagenesis of Upper Jurassic sediments from the elevated part of the Northern peri-Tethyan shelf: A comparative study on the Lochen area (Schw‰bische Alb) and the Cracow area (CracowóWielun Upland, Polen), Berlin. Geowiss. Abb. (E) 21:1ó111. Mehl, D., 1992, Die Entwicklung der Hexactinellida seit dem MesozoikumóPal‰obiologie, Phylogenie und Evolutionsˆkologie, Berliner Geowiss. Abh. (E) 2:1ó164. Meyer, R. K. F., and Schmidt-Kaler, H., 1989, Pal‰ogeographischer Atlas des s¸ddeutschen Oberjura (Malm ), Geol. Jb. A 115:3ó77. Montaggioni, L. F., and Camoin, G. F., 1993, Stromatolites associated with coralgal communities in the Holocene high-energy reefs, Geology 21:149 -152. Montgomery, S. L, 1993, Cotton Valley Lime of East Texas: New pinnacle reef play in the Late Jurassic, in: Petroleum Frontiers (Petroleum Information Gorp.), Vol. 10, pp. 1ó55. Montgornery, S. L., 1996, Cotton Valley Lime pinnacle reef play: Branton Field, AAPG Bull. 80:617629. Morsch, S. M., 1989, Scleractinian corals from the Oxfordian La Manga Formation in the NeuquÈn Basin, Argentina, Mem. Assoc. Australas. Palaeontols. 8:303ó306. Nose, M., 1995. Vergleichende Faziesanalyse uiid Palˆkologie korallenreicher Verflachungsabfolgen des iberischen Oberjura, Profil 8:1 ó237. Nose, M., submitted for publication, The modern (sub)tropical reef window, in: Reef Systems in Earth Histoiy (E. Fl¸gel and H. Zankl, eds.), Springer, HeidelbergóBerlin. Nose, M., and Leinfelder, R., 1997, Upper Jurassic coral communities within siliciclastic settings (Lusitanan Basin, Portugal, Implications for symbiotic and nutrient strategies), Proc. 8th Int. Coral Reef Symp. 2:1755ó1760. Nose, M., and Leinfelder, R. R., submitted for publication, The Upper Jurassic (sub)tropical reef window, in: Reef Systems in Earth History (E. Fl¸gel and H. Zankl, eds.), Springer, Heidelberg Berlin. Odum, E. P., 1983, Grundlagen der Ökologie, Thieme, Stuttgart. Palmer, T. J., and F¸rsich, F. T., 1981, Ecology of sponge reefs from the middle Jurassic of Normandy, Paloeontology 24:1ó23. Paulsen, S., 1964, Aufbau und Petrographie des Riffkomplexes von Arnegg im hˆheren Weiflen Jura der Schw‰bischen Alb (W¸rttemberg), Arbeiten aus dem Institut für Geologie und Paläontologie der Universität Stuttgart, NE. 42:1ó98. Pisera, A., 1997, Upper Jurassic siliceous sponges from the Swabian Alb: Taxonomy and Paleoecology, Palaeontol. Polonica 57:1ó216. Pittet, B., Strasser, A., and Dupraz, C., 1995, Palaeoecology, palaeoclimatology and cyclostratigraphy of shallow-water carbonate - siliciclastic transitions in the Oxfordian of the Swiss Jura. IAS-l6th Regional Meeting of Sedimentologyó 5iËme CongrËs Fran~ais de SÈdimentologie, ASF, Field Trip Guide Book, Publication ASF, Paris 23:225-254. Ponsot, C. M., and Vail, P. R., 1991, Sequence stratigraphy of the Jurassic: New data from the ParisLondon Basin, EUG VI-Congress, Strasbourg, Terra Cognita 28:48. P¸mpin, V. F., 1965, Riffsedimentologische Untersuchungen im Rauracien von St. Ursanne und Umgehung (Zentraler Schweizer Jura), Eclogae geol. HeIvetiae 58:799ó876. Ramalho, M., 1988, Sur Ia dÈcouverte de biohermes stromatolithiques ‡ spongiaires siliceux dans le KimmÈridgien de l'Algarve (Portugal), Comun. Serv. Geol. Portugal 74:41ó55. Reid, R. E. H., 1968, Bathymetric distribution of Calcarea and Hexactinellida in the present and the past, Geol. Mag. 105:546 -559. Reiswig, H. M., and Mackie, G. 0. 1963, Studies on Hexactinellid Sponges. III. The taxonomic status of Hexactinellida within the Porifera, Phil. Trans. Royal Soc. London B Biol. Sci. 301:419ó428.

308

Chapter 8

Reitner, J., 1993, Modern cryptic microbialite/metazoan facies from Lizard Island (Great Barrier Reef, Australia)óFormation and concepts, Facies 29:3ó40. Reitner, J., and Keupp, H., 1991, The fossil record of the haplosclerid excavating sponge Aka de Laubenfels, in: Fossil and Recent Sponges (J. Reitner and H. Keupp, eds.), Springer, Berlin, pp. 102ó120. Reitner, J., Wˆrheide, G., Thiel, V., and Gautret, P., 1996, Reef caves and cryptic habitats of lndoPacific reefsóDistribution patterns of coralline sponges and microbialites, in: Global and Regional Controls on Biogenic Sedimentation. 1. Reef Evolution. Research Reports (J. Reitner, F. Neuweiler, and F. Gunkel, eds.), Göttinger Arb. Geol. Paläont. Sb2:91ó100. Renesto, S., and Viohl, G., 1997, A sphenodontid (Reptilia, Diapsida) from the Late Kimmeridgian of Scharnhaupten (southern Franconian Alb, Bavaria, Germany), Archaeopteryx 15:27ó46. Rheinheimer, G., 1980, Aquatic Microbiology, 2 ed., Wiley and Sons, New York. Riegl. B., 1995, Effects of sand deposition on scleractinian and alcyonacean corals, Mar. Biol. 121:517ó526. Rogers, C. 5., 1990, Response of coral reefs and reef organisms to sedimentation, Mar. Ecol. Prog. Ser. 62:185ó202. Rˆper, M., Rothgaenger, M., and Rothgaenger, K., 1996, Die Plattenkalke von Brunn (Landkreis Regensburg). Sensationelle Fossilien aus dem Oberpfälzer Jura, Eichendorf Verlag, Eichendorf. Rosendahl, S., 1985, Die oberjurassische Korallenfazies von Algarve (S¸dportugal), Arb. Inst. Geol. Paläont. Univ. Stuttgart NE. 82:1-125. Roux, M., Bouchet, P., Bourseau J. P., Gaillard, C., Grandperrin, R., Guille, A. Q., Laurin, B., Monniao, C., Richer de Forges, B., Rio, M., Segonzac, M., Vacelet, J., and Zibrorius, H., 1991, L'Ètagement du benthos bathyal observe ‡ l'aide da la soucoupe CYANA, in: L'Environements Carbonate Bathyal en Nouvelle—Calédonie (B. Lambert and M. Roux, eds.), Doc. Travaux Inst. Géol. Albert-de-Lapparent 15:151ó165. Sartorio, D., 1989, Reef and open episodes on a carbanate platform margin from Malm to Cenomanian: The Cansiglio example (Southern Alps), Mem. Soc. Geol. Ital. 40:91ó97. Schlichter, D., 1992, A perforated gastrovascular cavity in the symbiotic deep water coral Leptoseris fragilis: A new strategy to optimize heterotrophic nutrition, Helgoländer Wissenschaftliche Meeresuntersuchungen 45:423ó443. Schmid, D. U., 1995, ,Tubiphytes“ morronensis—Eine fakultativ inkrustierende Faraminifere mit endosymbiantischen Algen, Profil 8:305ó317. Schmid, D. U., 1996, Marine Mikrobolithe und Mikroinkrustierer aus dem Oberjura, Profil 9:101ó251. Schmid, D. U., and Jonischkeit, A., 1995, The Upper Jurassic S„o Rom„o limestone (Algarve, Portugal, An isolated carbonate ramp, Profil 8:319ó337. Schmid, D. U., and Leinfelder, R. R., 1996, The Jurassic Lithocodium aggregatum—Troglotella incrustans foraminiferal consortium, Palaeontology 39:21ó52. Schuhmacher, H., 1976, Korallenriffe. Verbreitung, Tierwelt, Ökologie, BLV Verlagsgesallschaft. M¸nchen. Scotese, C. R., Walsh, D. B., Kraus, J. U., and Bocharova, N. Y., 1993, Plate evolution of Pangae from the Late Paleozoic to the Jurassic. Pangea Conference (Can. Soc. Petrol. Geol.), August 15ó19, 1993, Calgary, book of abstracts, p. 274, and PALEOMAP Project, International Lithosphere Program, Scott, R. W., 1988, Evolution of Late Jurassic and Early Cretaceous reef biotas, Palaios 3:184ó193. Stanley, G. D. jr., 1988; The history of Early Mesozoic reef communities: A three step process, Palaios 3:170ó183. Stanley, G. D. Jr., 1996, Recovery of reef communities after the Triassic mass extinction, Paleont. Soc. Sp. Publ. 8:370. Stanley, G. D., Jr., and Beauvais, L., 1994, Corals from an Early Jurassic coral reef in British Columbia: Refuge on an oceanic island reef, Lethaia 27:35ó47. Stanley, G. D., Jr., and McRoberts, C. A., 1993, A coral reef in the Telkwa Range, British Columbia: the Earliest Jurasic example, Can. J. Earth Sci. 30:819ó831.

Jurassic Reef Ecosystems

309

Stanley, G. D., Jr., and Swart, P., 1995, Evolution of the coralózooxanthellae symbiosis during the Triassic: A geochemical approach, Paleobiology 21:179ó199. Steiger, T., 1981, Kalkturbidite im Obarjura dar Nˆrdlichen Kalkalpen (Barmsteinkalke, Salzburg, ÷sterreich), Facies 4:215ó348. Steiger, T., and Jansa, L. F., 1984, Jurassic limestones of the seaward edge of the Mazagan Carbonate Platform, Northwest African continental margin, Morocco, Initial Reports, DSDP 79:449ó491. Steiger, T., and Wurm, D., 1980, Faziesmuster oberjurassischer Plattformkarbonate (Plassenkalke, Steiermark), Facies 2:241ó284. Takacs, M., in prep., Vergleichende Analyse zeitgleicher oberjurassischer Korallen- und Kieselschwammriffe aus dem Schweizer Jura, unpublished dissertation, University of Stuttgart. Taylor, P. D., and Palmer, T. J., 1994, Submarine cavas in a Jurassic reef (La Rochelle, France) and the evolution of cave biotas, Naturwissenschaften 81:357ó360. Trammer, J., 1988, Ecalogic history of the Oxfordian sponge assamblage in the Polish Jura Chain, Berliner Geowiss. Abh. A 100:44ó45. Turnsek, D., Buser, S., and Ogorelev, B., 1981, An Upper Jurassic reef complax from Slovenia, Yugaslavia, in: European Fossil Ree fModels (D. F. Toomey, ed.), Soc. Econ. Paleont. Mineral. Sp. P. 30:361ó369. Wagenplast, P., 1972, ÷kologische Untersuchung der Fauna aus Bank- und Schwammfazias des Weiflen Jura der Schw‰bischen Alb, Arb. Inst. Geol. Paläont. Univ. Stuttgart N.F. 67:1ó99. Walker, K. R., and Alberstadt, L. P., 1975, Ecological succession as an aspect of structure in fossil communities, Paleobiology 1:238ó 257. Warme, J. E., Burke, R. B., Crevello, P. D., Halliwell-Haziett, B., and Letsch, D. K., 1988, Evolution of the Jurassic High Atlas Rift, Morocco: Transtension, structural and eustatic controls on carbonate facies: Am. Assoc. Petrol Geol. Mediterranean Basins Conf. Nice, Sept. 1988, Fieldtrip 9. Guidebook. Werner, W., 1986, Palˆkalogische und biofazialle Analyse des Kimmaridge (Oberjura) von ConsalaÁ„o, Mittelportugal, Zitteliana 13:1ó109. Werner, W., Leinfelder, R. R., F¸rsich, F. T., and Krautter, M., 1994, Comparative palaaoecology of marly coralline sponge-bearing reefal associations from the Kimmeridgian (Upper Jurassic) of Portugal and Southwestern Germany. Cour. Forsch. Inst. Senckenb. 172:381ó397. Wiedenmayer, F., 1980, Spicules and sponges in the lower Jurassic of the western Tethys, Sedimenta 8:135ó145. Wilkinson, C. R., and Evans, E., 1989, Sponge distribution across Davies Reef, Great Barriar Reef, relative to location, depth, and water movament, Coral Reefs 8:1ó7. Wilkinson, C. R., and Trott, L. A., 1985, Light as a factor determining the distribution of sponges across the central Great Barrier Raaf, Proc. 5th Int. Coral Reef Congr. Tahiti 5:125ó130. Wilson, R. C. L., Hiscott, R. N., Willis, M. G., and Gradstein, F. M., 1989, The Lusitanian Basin of west central Portugal: Mesozoic and Tertiary tectonic, stratigraphy and subsidence history, in: Extensional Tectonics and Stratigraphy of the North Atlantic Margins (A. J. Tankard, and H. Balkwill, eds.), AAPG Mem. 46:341ó361.

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Important note: This is an informal digital reprint of the below paper provided for your personal use, since no more reprints are available by the author. Text and figures are identical with the original paper. However, some figure patterns might be rendered slightly different to the original paper and landscape sized figures are turned 90° for better online readability. Also, there might be some additional spelling mistakes (owing to OCRrecogition). Line feed returns can also be different to the original text but page feed returns are identical with the original. A few spelling mistakes of the original paper were corrected (but the original version was kept as crossed-out word)

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Reinhold R. Leinfelder Institute for Paleontology and Historical Geology, University of M¸nchen, Richard-Wagner-Str. 10, D80333 M¸nchen, Germany

Jurassic Reef Ecosystems in:

The History and Sedimentology of Ancient Reef Systems Edited by

George D. Stanley, Jr. University ofMontana Missoula, Montana

Kluwer Academic /Plenum Publishers New York, Boston, Dordrecht, London, Moscow

---------------Leinfelder, R.R. (2002): Jurassic Reef Ecosystems.- In: Stanley, G.D.Jr. (ed.), The History and Sedimentology of Ancient Reef Systems, pp. 251-309, Kluwer Academic/Plenum Publishers, New York.