The most thoroughly studied bioherms are along the middle reaches of the Lena. River, between Titirikteekh Creek and Zhurinskiy Mys' (Zhuravleva 1960,1966; ...
Facies from Palaeozoic reefs and bioaccumulations
Memoires du Museum national d'Histoire naturelle Tome 195
edited by
Emmanuelle VENNIN m, Markus ARETZ (», Frederic BOULVAIN B & Axel MUNNECKE (4)
m U M R 5 5 6 1 CNRS Biogeosciences, Universite d e B o u r g o g n e 2, b o u l e v a r d G a b r i e l 2 1 0 0 0 D i j o n - France
l ! l
Institut fur Geologie u n d Mineralogie
U n i v e r s i t a t z u K o l n - Z i i l p i c h e r strasse 4 9 a 50 6 7 4 Koln - G e r m a n y
3 l
Petrologie sedimentaire
B 2 0 , Sart T i l m a n , U n i v e r s i t e d e L i e g e 4 0 0 0 Liege - B e l g i u m i« I n s t i t u t f u r P a l a e o n t o g i e Universitat zu Erlangen, Loewenichstrasse 2 8 91 0 5 4 Erlangen - G e r m a n y
Publications Scientifiques du Museum Paris 2007
CAMBRIAN
EARLY C A M B R I A N ( T O M M O T I A N ) A R C H A E O C Y A T H A N - M I C R O B I A L B I O H E R M S , SIBERIAN P L A T F O R M LOCALITY. — Early Cambrian (Tommotian; Fig. 1, p. 16) tropical platform ramp, Siberian Platform, Russia. Reefs are best developed w i t h i n the narrow Anabar-Sinsk fades belt, transitional between broad restricted evaporitic and open marine carbonate belts (Fig. 9). The most thoroughly studied bioherms are along the middle reaches of the Lena River, between Titirikteekh Creek and Zhurinskiy Mys' (Zhuravleva 1960,1966; Kruse et al. 1995), but extend along the length of the Anabar-Sinsk fades belt from Uchur River i n the southeast to Igarka i n the northwest. STRATIGRAPHY. — Isit' Member (transgressive systems tract) of the Pestrotsvet Formation along the Lena river, where the formation is about 350 m thick; equivalent Tommotian units elsewhere.
F I G . 9 . P a l a e o g e o g r a p h i c m a p o f S i b e r i a n P l a t f o r m f o r m i d d l e - T o m m o t i a n t i m e . F a d e s b e l t s : I = T u r u k h a n s k - l r k u t s k - O l e k m a ( w e s t e r n ) ; II = A n a b a r - S i n s k ( t r a n s i t i o n a l ) ; III = Y u d o m a - O l e n e k ( e a s t e r n ) . A n a b a r - S i n s k b i o h e r m a l t r a c t s : 1 = m i d d l e L e n a r i v e r ; 2 = A m g a r i v e r ( s u b s u r f a c e only); 3 = m i d d l e A l d a n river; 4 = u p p e r U c h u r river; 5 = M a r k h a - U d a c h n y y area ( s u b s u r f a c e o n l y ) ; 6 = w e s t e r n A n a b a r massif; 7 = Igarka a r e a ( S u k h a r i k h a River); 8 = O l e n e k u p l i f t ; a n d 9 = K h a r a - U l a k h m o u n t a i n s ; f r o m K r u s e e t a / . ( 1 9 9 5 ) .
38
PETER D.
KRUSE
FACIES A N D MICROFACIES (Figs 10-25). — Argillaceous limestone and calcareous siltstone of the Isit' Member were deposited o n a broad, shallow subtidal carbonate platform subject to episodic storm reworking. Bioherms, consisting of metre-scale m o u n d s occurring singly or stacked together (Figs 10-11), flourished along the Anabar-Sinsk facies belt of the platform. I n the mounds, modular archaeocyaths (e.g., Archaeolynthus
polaris, Cambrocyathellus
spp.) remained upright,
acting as bafflers, whereas most sticklike archaeocyaths (the majority) are preserved toppled. Archaeocyaths were capable of producing stereoplasm (laminated secondary calcareous skeleton) for fixation-support, thus enhancing their framebuilding capacity (Fig. 12). The calcimicrobe Renalcis jacuticus
was however the principal framebuilder,
constructing bushes, crusts and dense masses, as well as being cryptic w i t h i n reef cavities. Framebuilding was thus by a consortium of dominant encrusting Renalcis jacuticus and subsidiary attaching archaeocyaths and the coralomorph Cysticyathus tunicatus. Marine fibrous calcite cement (Figs 12-13) encrusted all other constituents and was actually paramount i n bioconstruction. Biohermal cavities are bioclast-supported (shelter cavities; Fig. 14) or unsupported i n lime m u d (open burrows, stromatactis; Fig. 13). Renalcis jacuticus and monocyathide (e.g., solitary
Archaeolynthus)
and archaeocyathide archaeocyaths were cryptic w i t h i n the cavities. Although subsidiary framebuilders, archaeocyaths contributed by baffling lime m u d ( i n the case of modular ramose forms such as Archaeolynthus polaris, primigenius
Tumuliolynthus
and Cambrocyathellus spp.), by providing surfaces (including shelter cavities) for precipitation of fibrous
cement, and by directly encrusting and binding via stereoplasm (mainly
Dictyocyathus).
Red argillaceous limestone and calcareous siltstone and grey, yellowish or reddish bioclast limestone constituted the interbiohermal sediment (Fig. 15). The more argillaceous beds supported a soft-bodied infauna, their activity n o w preserved as ichnofossils (Fig. 16). Some bioherms shed bioclast debris to create a distinctive apron of peribiohermal sediment w i t h common archaeocyath sticks, hyoliths and small skeletal fossils (Fig. 17). Kruse et al. (1995) recognized a suite of component domains, consisting of varying proportions of archaeocyaths, calcimicrobes, cement and essentially automicritic m u d : Domain 1 — archaeocyaths and m u d (in situ accumulations w i t h bioclast floatstone and rudstone textures) Domain 1A — disoriented archaeocyaths and m u d (Fig. 18) Domain I B - oriented ramose archaeocyaths and m u d (Fig. 19) Domain 1C - archaeocyaths w i t h stereoplasm and m u d (Fig. 20) Domain 2 — Renalcis and archaeocyaths (boundstone textures) Domain 2A— archaeocyath-rich (Fig. 21) Domain 2B — Renalris-rich (Fig. 22) Domain 3 — archaeocyaths and fibrous cement (bioclast cementstone textures) Domain 3A — archaeocyath sticks and cement (Figs 23-24) Domain 3B — archaeocyath bowls and plates and cement (Fig. 25). Using these categories, the following temporal and spatial trends i n bioherm construction were documented by Kruse et al. (1995), i n chronological order f r o m the oldest to the youngest zones of the T o m m o t i a n Stage (Fig. 26): - sunnaginicus
Zone (see also Zhuravleva 1960, 1966; Rozanov & Sokolov 1984; Riding & Zhuravlev 1995) —
Aldan river near Ulakhan Sulugur: mostly domain 2A. - regularis Zone, tortuosa Subzone — Titirikteekh creek: unpatterned mosaic of domains 1 A, 3A and 2A w i t h lesser I B and 1C, and w i t h diffuse domain transitions, i n w h i c h only 2A, 3A and minor 1C contribute to rigid framework construction; peribiohermal sediment of composition intermediate between purer lime m u d of the bioherms and more argillaceous interbiohermal sediment, i.e. a large-stick archaeocyath or hyolith floatstone, or rudstone cemented by fibrous calcite, or intraclast rudstone to grainstone. - regularis Zone, tortuosa Subzone — Churan: Titirikteekh-type bioherms are present, together w i t h distinctive bioherms dominated by Renakis-rich domain 2B and w i t h minor 1A I B and 3A largely confined to interstices between Renalcis masses; i n somewhat coarser-grained interbiohermal sediment and w i t h little or no discrete peribiohermal sediment.
CAMBRIAN
F I G S 1 0 - 1 5 . T o m m o t i a n b i o h e r m s , L e n a river. N o t e a d j a c e n t b e d s d i p p i n g b e n e a t h b i o h e r m . 1 0 , T i t i r i k t e e k h C r e e k . 1 1 , C h u r a n . B i o h e r m c o m p o n e n t s (12-14) a n d peri- a n d i n t e r b i o h e r m a l s e d i m e n t s (15-17), T i t i r i k t e e k h creek. 1 2 , Sticklike a r c h a e o c y a t h
(longitudinal section, centre) attaching t o
a n o t h e r a r c h a e o c y a t h ( t r a n s v e r s e s e c t i o n , r i g h t ) via s t e r e o p l a s m ( d a r k ) . B o t h a r e e n c r u s t e d b y b u s h y Renalcis
jacuticus,
a n d all a r e i n t u r n e n c r u s t e d
b y p a l e m a r i n e f i b r o u s c e m e n t ( b o t t o m a n d l e f t ) ; scale = 2 , 5 m m . 1 3 , C r y p t i c b u r r o w s ( p a l e ) w i t h i n r e d d i s h i n t e r n a l l i m e m u d i n f i l t r a t e d i n t o a s t i c k l i k e a r c h a e o c y a t h ( l e f t ) a n d c o r a l o m o r p h Cysticyathus
tunicatus
( r i g h t ) . B o t h s k e l e t o n s a r e t h i n l y e n c r u s t e d b y Renalcis
p a l e m a r i n e f i b r o u s c e m e n t ; scale = 2,5 m m . 1 4 , S h e l t e r c a v i t y b e n e a t h b o w l - s h a p e d a r c h a e o c y a t h Sakhacyathus e n c r u s t e d b y Renalcis
jacuticus,
subartus.
jacuticus,
f o l l o w e d b y m a r i n e f i b r o u s c e m e n t . R e m a i n d e r o f c a v i t y is p a r t i a l l y f i l l e d b y g e o p e t a l i n t e r n a l b i o c l a s t i c l i m e m u d
a n d o c c l u d e d b y l a t e r e q u a n t c e m e n t ; scale = 2,5 m m . 1 5 , I n t e r b i o h e r m a l s e d i m e n t : g r e y c a l c a r e o u s b e d ( t o p ) w i t h a r c h a e o c y a t h s virgatus
a n d in t u r n b y
C a v i t y c e i l i n g is i n i t i a l l y {Nochoroicyathus
a n d o t h e r s ) , calcimicrobial m e s o c l o t s a n d small skeletal fossils, o v e r l y i n g a d a r k reddish argillaceous l i m e m u d b e d w i t h t h e s a m e suite o f
b i o c l a s t i c c o n s t i t u e n t s ; scale = 2,5 m m .
39
PIERRE D .
KRUSE
F I G S 1 6 - 2 1 . 1 6 , I n t e r b i o h e r m a l s e d i m e n t : b e d d i n g p l a n e v i e w o f i c h n o f o s s i l s Rhizocorallium
jenense
a n d Chondrites
s p . ; scale = 1 c m . 1 7 , P e r i b i o h e r m a l
s e d i m e n t : p r o s t r a t e stick a n d b o w l a r c h a e o c y a t h s p r e s e r v i n g s h e l t e r p o r o s i t y , n o w i n f i l l e d by p a l e m a r i n e f i b r o u s c e m e n t , b e t w e e n i n f i l t r a t e d g e o p e t a l b i o c l a s t i c , a r g i l l a c e o u s l i m e m u d ; scale = 5 m m . B i o h e r m a l d o m a i n s : 1 8 , D o m a i n 1 A ( d i s o r i e n t e d a r c h a e o c y a t h s a n d m u d ) , T i t i r i k t e e k h C r e e k . N o t e u n s u p p o r t e d c a v i t i e s i n t h e m u d , w i t h p a r t i a l g e o p e t a l i n f i l l s o f paler, less a r g i l l a c e o u s l i m e m u d i n c o r p o r a t i n g b u r r o w s ; scale = 5 m m . 1 9 , D o m a i n ( o r i e n t e d r a m o s e a r c h a e o c y a t h s a n d m u d ) b a f f l e s t o n e b a s e d o n r a m o s e Archaeolynthus
polaris,
scale = 5 m m . 2 0 , D o m a i n 1C ( a r c h a e o c y a t h s w i t h s t e r e o p l a s m a n d m u d ) w i t h Nochoroicyathus b y Sakhacyathus
subartus
b o w l . Okulitchicyathus
( p a l e , l o w e r l e f t ) . C o r a l o m o r p h Cysticyathus archaeocyaths,
discoformis tunicatus
virgatus
s t i c k ( t o p m a r g i n ) e n c r u s t e d via
p l a t e ( b o t t o m l e f t c o r n e r ) is d i r e c t l y e n c r u s t e d b y r e c r y s t a l l i s e d Dictyocyathus
b e l o w S. subartus
a r c h a e o c y a t h - r i c h ) , T i t i r i k t e e k h C r e e k ; scale = 5 m m .
1B
Zhurinskiy Mys'. Section tangential t o m o u n d surface; stereoplasm translucidus
b o w l ( r i g h t ) , Z h u r i n s k i y M y s ' ; scale = 5 m m . 2 1 , D o m a i n 2 A (Renalcis
and
CAMBRIAN
F I G S 2 2 - 2 5 . 2 2 , D o m a i n 2B (Renalcis polaris
a n d a r c h a e o c y a t h s , /?ena/c/s-rich) c a l c i m i c r o b e b o u n d s t o n e w i t h t o p p l e d o r p o s s i b l y c r y p t i c
Archaeolynthus
( l e f t ) , C h u r a n ; scale = 2,5 m m . 2 3 , D o m a i n 3 A ( a r c h a e o c y a t h s t i c k s a n d f i b r o u s c e m e n t ) ; c a v i t y o c c l u d e d b y e q u a n t s p a r c e m e n t ( t o p r i g h t ) ,
T i t i r i k t e e k h C r e e k ; scale = 2,5 m m . 2 4 , B i o h e r m t o p w i t h u p r i g h t a r c h a e o c y a t h s t i c k s ( d o m a i n 3 A ) p r e s e r v e d i n life p o s i t i o n b y m a r i n e f i b r o u s c e m e n t ( w h i t e ) , T i t i r i k t e e k h C r e e k . L e n s c a p ( t o p r i g h t ) is 5 0 m m d i a m e t e r . 2 5 , D o m a i n 3 B ( a r c h a e o c y a t h b o w l s a n d p l a t e s a n d f i b r o u s c e m e n t ) i n f i l l i n g s h e l t e r c a v i t y b e n e a t h a r c h a e o c y a t h p l a t e ( t o p ) , T i t i r i k t e e k h C r e e k ; scale = 2,5 m m .
- regularis Zone, tortuosa Subzone — Zhurinskiy Mys' lower beach: earliest bioherms w i t h indication of spatial regularity i n distribution of domains: outer r i n d of domain I B principally of radially oriented ramose Archaeolynthus polaris, encasing core mainly of domain 1A, possibly an ecological succession; Zhurinskiy Mys' upper beach: m u d rich mounds w i t h domains 1C, 1A and m i n o r 3B, i n w h i c h archaeocyathan stereoplasm (domain 1C) contributes significantly to framework construction; little peribiohermal sediment around either bioherm type. - regularis Zone, bella Subzone — Byd'yangaya creek: amalgam of domains 2B, 1A and i n shelter cavities, 3B, characterized by large archaeocyath sticks and bowls w h i c h create shelter cavities lined by thick rinds of fibrous cement; i n coarse interbiohermal sediment of locally low-angle cross-laminated bioclast rudstone to grainstone as well as argillaceous limestone. - lenaicus-primigenius Zone - Byd'yangaya creek: alternating bedded Renalcts-poor and Rena!cis-rich domains 1A and 2B respectively, also w i t h shelter cavities beneath archaeocyath sticks and occasional plates.
41
PIERRE D .
KRUSE
1A + 2B
o qj
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II
Byd' Yang Aya Creek 1 A + 2 B + 3B
Byd' Yangaya Creek 1 C + 1 A(3B)
CO
3
c CO
£
CO 3 •C
I 1-2
1A+2A+3A (1B + 1C)
Qo
upper beach 2B
1At
( 1 A + 1B + 3A)
1B
I Titirikteekh CO
is o o e
Churan 2B (2A)
Aldan
}5£
•
Sa CD •Q
cj
a try
CO CO
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L e g and
V
-2 -2 CO Q
lower beach Zhurinski y Mys'
Aldan
cement large stick archaeocyaths stereoplasm bowl archaeocyaths ramose archaeocyaths
Renalcis mud stick and bowl archaeocyaths
F I G . 2 6 Schematic d i a g r a m s s h o w i n g b i o h e r m d e v e l o p m e n t t h r o u g h t h e T o m m o t i a n , southeastern Siberian Platform. Biostratigraphic z o n a t i o n at l e f t , l i t h o s t r a t i g r a p h y a t r i g h t ; f r o m K r u s e e f al. ( 1 9 9 5 ) .
CAMBRIAN
BIODIVERSITY A N D TAPHONOMY. - Diverse biota of archaeocyaths (at least 25 species); spiculate sponges (two forms); coralomorph Cysticyathus tunicatus; calcimicrobe Renalcis jacuticus; anabaritids; molluscs (at least 10 species); hyoliths (at least 16 species); coleolid Coleolella billingsi; coeloscleritophorans (at least 7 species); hyolithelminths (at least 7 species); t o m m o t i i d s (at least 6 species); and brachiopod Aldanotreta
sunnaginensis. The ichnofossils
Rhizocorallium jenense, Chondrites sp. and vertical burrows occupied interbiohermal sediment.
DISCUSSION. — The Tommotian Stage of the Siberian Platform uniquely preserves the earliest archaeocyathan faunas anywhere, and the bioherms of its Anabar-Sinsk facies belt are therefore the earliest examples of the Early Cambrian reef-building phase, the first of the Phanerozoic. Only i n the succeeding Atdabanian Stage d i d archaeocyaths colonise adjacent terranes.
REFERENCES KRUSE P. D., Z H U R A V L E V A . Y u . & J A M E S N. P. 1 9 9 5 . —
Primordial meta-
z o a n - c a l c i m i c r o b i a l r e e f s : T o m m o t i a n (Early C a m b r i a n ) o f t h e S i b e r i a n P l a t f o r m . Palaios
10: 2 9 1 - 3 2 1 . Structure a n d diversity of oldest
s p o n g e - m i c r o b e r e e f s : L o w e r C a m b r i a n , A l d a n River, S i b e r i a .
Geology
R O Z A N O V A . Y u . & S O K O L O V B. S. (eds) 1 9 8 4 . — kembriya.
Stratigrafiya
Yarusnoe
raschlenenie
[ S t a g e scale o f t h e L o w e r C a m b r i a n .
S t r a t i g r a p h y ) . N a u k a , M o s c o w , 1 8 4 p.
Platformy
[Archaeocyaths
R a n n e k e m b r i y s k i e o r g a n o g e n n y e p o s t r o y k i na
t e r r i t o r i i S i b i r s k o y P l a t f o r m y [Early C a m b r i a n o r g a n o g e n i c b u i l d u p s o n t h e t e r r i t o r y o f t h e S i b e r i a n P l a t f o r m ] , in G E K K E R R. F. ( e d . ) , Organizm v geologicheskom
23: 649-652.
Sibirskoy
o f t h e S i b e r i a n P l a t f o r m ] . A k a d e m i y a N a u k SSSR, M o s c o w , 3 4 4 p. Z H U R A V L E V A I. T. 1 9 6 6 . —
R I D I N G R. & Z H U R A V L E V A . Y u . 1 9 9 5 . —
nizhnego
Z H U R A V L E V A I. T. 1 9 6 0 . — Arkheotsiaty
proshlom
isreda
[ O r g a n i s m a n d e n v i r o n m e n t in t h e g e o l o g i -
cal p a s t ] . N a u k a , M o s c o w : 6 1 - 8 4 .
