Distribution of the archaeocyath-calcimicrobial bioconstructionson the Early Cambrian shelves
Anna Gandin a,∗, Francoise Debrenne b
a Dipartimento di Scienze della Terra, Via Laterina 8, 53100 Siena, Italyb UMR 514, 13, rue du long foin, Sainte Geneviève des bois 91700, France
Received 18 January 2010; received in revised form 26 April 2010; accepted 10 September 2010Available online 21 September 2010
bstract
The differences and variety of structural, depositional, and compositional features observed in the Early Cambrian microbial-archaeocyathuildups preserved in the present-day continents, suggest a direct correlation between the physico-chemical factors of deposition and the structuralrchitecture of the buildups. This can be explained in terms of their palaeogeographic collocation on the shelves (depth, energy), and hence of thereal distribution of epeiric basins and perioceanic/pericontinental platforms.
Data on the analysis of biohermal communities and their architectures indicate that the relative development of the main reef-building components,s well as their evolution within the reef communities, reflects the dominant physico-chemical factors, mainly temperature and nutrient availability,nd the physiography of the primary depositional setting. The bioaccumulations show different reef building styles, defined by the types ofssociated facies and by the early diagenetic features. They are represented by (i) mud-supported simple (Kalyptrae) to compound mounds locallyith stromatactis-like cavities; (ii) dendrolitic bioherms and crustose buildups with large shelter cavities and low synoptic relief; (iii) cement-
upported skeletal reefs with wave resistant frameworks often associated with oolitic shoals, and (iv) bioclastic sands, developed at photic andhallow sub-photic depths on low-angle/low-energy ramps (i–ii) or on high-energy conditions on platforms distally rimmed (iii) or occasionallywept by storm currents (iv).
The results of the analysis provide information on the spatial conditions of the primary depositional settings of the first metazoan involved in
eef building in the history of the Earth, and suggest that the architecture of the bioconstructions was controlled not only by the physiography ofhe depositional setting and global/astronomic climate but also by local climatic conditions constrained by the latitudinal distribution of the Earlyambrian continental blocks.2010 Elsevier Ltd and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.
ttsrtd
eywords: Archaeocyaths; Calcimicrobes; Bioconstructions; Early Cambrian
. Introduction
The differences in architecture and the variety of struc-ural, depositional, and compositional features observed in thearly Cambrian microbial-archaeocyath buildups preserved in
he present-day continents have been explained in terms oflobal climate and palaeogeographic collocation on the shelvesCourjault-Radé et al., 1992; Savarese et al., 1993; Rowland and
hapiro, 2002) whereas the influence of temperature and nutrientvailability has been less considered (Wood et al., 1993; Ridingnd Zhuravlev, 1995).
The analysis of the different reef building styles, defined byhe types of associated facies and by the early diagenetic fea-ures, can provide information on the latitudinal/climatic andpatial conditions of the primary depositional setting since theelative development of the main reef-building components andheir evolution within the reef communities appear to reflect theominant physico-chemical factors of the environment.
Cambrian bioaccumulations have been widely assumed inhe past to represent reef communities and for comparison withecent analogues, ascribed to tropical warm waters (Debrenne,959; James and Klappa, 1983; Rowland and Gangloff, 1988;
ebrenne and Courjault-Radé, 1994; Debrenne and Zhuravlev,996; Zhuravlev, 2001). However, the temperatures of the watern a deep setting of the tropical zone may equate to the tem-eratures of shallow water in higher latitudes. Consequently,
cool-water” communities might have played an important rolen the formation of Phanerozoic bioconstructions.
Early Cambrian world-wide bioaccumulations can be dividedn two main categories:
1) Mound-type buildups, dominated by lime-mud and/orcalcimicrobes with accessory solitary regular or simplemodular archaeocyaths, that lived on a soft substrate inmildly eutrophic or oligotrophic conditions, in deeperwaters at low-latitude or in shallow, temperate/cool condi-tions at high-latitude. The normal-to-slightly saline waterswere rich in nutrients, coming from the mainland or fromupwelling currents along the west facing coasts of conti-nents. This type of construction is commonly associatedwith bioclastic storm-generated floatstones. Non-skeletalallochems are conspicuously absent.
2) Biohermal frameworks composed of complex, modularcolonies of archaeocyaths having a real frame-buildingpotential, associated with calcimicrobes and cements,which show the typical architecture of Recent, wave-resistant reefs. The modular archaeocyaths concurred withRenalcis to build wave-resistant, often cement-supported,sometimes ecologically zoned constructions. Epiphyton,coralomorphs, and radiocyaths were common accessoriespresent in the community. This kind of consortium has beeninterpreted as living in a probable photosymbiotic regime(Rowland and Shapiro, 2002), also suggested by the obser-vation (Camoin et al., 1989) of the presence of “putativebacteria” (Debrenne, 2007) within the skeletal elements ofarchaeocyaths, and therefore able to live in warm, nutrient-poor waters on low-latitude coasts.
A variety of allochem sands, and in particular ooliticgrainstone forming shoal complexes, are commonly associ-ated with this type of construction.
The distribution in space and time of the archaeocyath-alcimicrobe buildups appears to reflect the evolution of therchaeocyaths with a peak in the Botoman Stage when most ofhe shelves were positioned in the tropical zone, and a drasticecrease in the Toyonian Stage when most of the continen-al masses began to drift towards the southern pole, exceptntarctica which still located in low latitudes, harboured a few
rchaeocyath communities during Middle and even Late Cam-rian. The remaining Middle Cambrian carbonate platformsere located in high latitudes and inhabited by photoautrophicrobes, probably the only calcareous secreting organisms able
o survive the Early/Middle Cambrian cooling crisis.
. History of research
The international community of coral specialists, who before971 used to communicate their current researches throughnformal groups in USA, France, and the former URSS, were
eady to follow the recommendation of the academician B.S.okolov during the first international meeting in Novosibirsk inugust 1971, to establish an International Committee on Fos-
il Corals (and later some other coelenterates and Porifera) and
CSis
world 19 (2010) 222–241 223
elated reefal structures, and to organize periodical meetingsn different countries once in every four years. All special-sts, the survivors of the 1st meeting (including the seconduthor of this paper) as well as newcomers, met as a markf their esteem and gratitude, in St Petersburg in August007 for the Xth Symposium to celebrate the 90th anniver-ary of the founder of the Association, Academician Borisergueievitch Sokolov. The impact of the numerous investiga-
ions on all fossil groups and related subjects and the progressbtained are unquestionably attested by the contributions pre-ented in the successive Symposia and published in specialolumes.
Concerning the Early Cambrian Archaeocyatha, two impor-ant unsettled problems were presented for the first time atifferent Symposia: their place in the living world and their rolen the Cambrian bioconstructions.
Since their discovery in the mid-nineteenth century, onhe basis of superficial similarities, archaeocyaths have beenttributed to a variety of groups including corals, sponges, pro-ists, and algae. In 1971, they were, almost generally, regarded asn independent phylum. At the IVth meeting (Washington 1983),ebrenne and Vacelet (1984) demonstrated that they belong to
he phylum Porifera by scientific comparisons of the structuralrganisation of archaeocyaths with that of recent sponges hav-ng a massive calcareous skeleton, with or without spicules. Thisosition was possible only after the discovery by scuba divers ofponges with massive calcareous skeleton, living in submarineaves of the Caribbean. At last, consensus was reached on con-idering Archaeocyatha as a Class among the Porifera (Debrennet al., 2002b).
The term “reef” was used from the beginning to describerchaeocyath settings by geologists working in USA, Sardinia,ussia, and Australia. Archaeocyatha and associated “algal”rganisms (now thought to be related to calcified microbes) werenterpreted as responsible for constructions comparable with thereat Barrier Reef (Hyatt, 1885). Detailed investigations tooklace only after I.T. Zhuravleva’s pioneer works (Zhuravleva andelenov, 1955). She was the first to propose several types of “bio-erms” according to their biological components (Zhuravleva,960) and was followed by the Russian authors. At the 3rd meet-ng (Warsaw, 1979), Francoise Debrenne, in collaboration withhe eminent specialist on carbonates Noël James, provided a syn-hesis of all data published in the USSR from 1955 to 1977 onrchaeocyath-rich bioherms and their major components, allow-ng western specialists to have access to the Russian literaturetherwise not readily available.
Noël James and collaborators (James and Kobluk, 1978;ames and Debrenne, 1980; Debrenne and James, 1981;ames and Gravestock, 1990; Kruse et al., 1995) proposed aethod of quantification of the reef components, based on the
etailed mapping of the different biological and abiotic domainsFigs. 1 and 2). This method adopted since 1980 by most of thecientists studying the bioconstructions throughout the Early
ambrian world (Table 1) has been recently applied to Laentinella reef in Sardinia (Fig. 3): the different sedimentolog-
cal and fossil components were located and quantified in gridquares measuring 30 × 30 cm (Gandin et al., 2007).
224 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
Table 1Distribution of the Lower Cambrian archaeocyathan reefs.
Stratigraphic distribution Locality Authors Reef types and components
Tommotian (regularis,lenaicus-primigeniuszones)
RussiaSiberian Platform
Kruse et al. (1995) single; stacked, 1–3 m1. archaeocyaths and mud2. Renalcis dominant builders3. archaeocyaths bowls, plates, shelter cavities and cements
Tommotian (A. sunnaginicuszone)
RussiaAldan RiverUlakhan Sulugur
Riding and Zhuravlev(1995)
single, 1 m 68 × 1 m 12builder dominant: archaeocyaths5 successive stages of development
Tommotian (D. regularis-D.lenaicus zone)
RussiaLena RiverTitiriktek
Zhuravleva (1966, 1972) isolated Kalyptrae, 0.5 m × 0.5–2 mseveral levels of stacked Kalyptrae 45 m highbinders Renalcis and cement, archaeocyaths at top and flanks
Zadorozhnaya (1974) calcimicrobial-archaeocyath single Kalyptra 5 m × 8 mand complex stacked Kalyptrae up to 80 m
Kameski-Sanachtykgol MongoliaWestern Mongolia
Voronin and Drozdova(1976), Drosdova (1980)
single Kalyptrae from 1 to 10 mcomplex reef with stacked Kalyptrae h < 100 mclassical types:Renalcis dominant with associated calcimicrobesarchaeocyath dominant, rare calcimicrobesRenalcis-Epiphyton + archaeocyathsregulares dominant in diversity
Wood et al. (1993) single complex1. builders: dominant archaeocyaths-radiocyaths-calcimicrobes2. calcimicrobes, rare archaeocyaths3. Cambrocyathellus-calcimicrobes, moderate to high energyconditions to deep water
Kruse et al. (1996) Type 1. Gordonophyton-Girvanella crusts, cryptic community ofcribricyaths, coralomorphs and archaeocyathsType 2. radiocyath-archaeocyath bioherms, modular and encrustingforms as binders; minor calcimicrobesType 3. calcimicrobial bioherms, archaeocyaths rare
Toyonian(Tianheban Formation)
ChinaYangtze Province
Debrenne et al. (1991) isolated Kalyptrae1. solitary archaeocyath with exocyathecal tissue, encrusted byRenalcis, Epiphyton and Girvanella2. modular branching archaeocyaths linked by exocyathecal tissuesmaller calcimicrobes
Botoman(Xiannüdong Formation)
ChinaShaanxi Province
Yuan et al. (2001) 10 levels of archaeocyath bioherms 2–3 m high, along a 30 km belt,Renalcis dominant and Girvanella
Atdabanian(Issendalenian)
MoroccoN. Anti-Atlas
Debrenne et al. (1992),Debrenne and Debrenne(1995)
simple 1 m × 1–2 mRenalcis + rare Archaeocyaths-bafflestone with modulararchaeocyaths = Epiphyton-Renalcisdominant + Girvanella + modular archaeocyaths and large cupssheltering cavities
Botoman (Banian 1–2) MoroccoN. Anti-Atlas
Debrenne et al. (1992),Debrenne and Debrenne(1995), Álvaro andDebrenne (2007)
giant reef 20 m × 100 mRenalcis dominant boundstonelocally archaeocyath frameworkcomplex accumulation, H: 2 m × 2–3 m up to 200 m
Botoman (Banian 1–2) MoroccoS. Anti-Atlas
Debrenne (1975),Debrenne et al. (1992),Debrenne and Debrenne(1995)
Debrenne et al. (1992),Debrenne and Debrenne(1995)
simpleRenalcis dominant
Atdabanian FranceNormandie
Debrenne (1958), Doré(1972)
Kalyptra: 0.25–0.50 m, dominant oligotypic assemblagesmodular-branching archaeocyaths, Epiphyton, Girvanellaopen shelf, low energy
A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241 225
Table 1 (Continued)
Stratigraphic distribution Locality Authors Reef types and components
Botoman FranceMontagne Noire
Debrenne et al. (2002a) pioneer reefs, Epiphyton, Girvanella, scattered archaeocyathslow energy, subtidalmud-mounds with dominant Epiphyton, minor Renalcis andsaucer-like Anthomorpha sheltering cavities and marine cementhigh energy
Atdabanian (Ovetian) SpainSerra di CordobaZafra-AlconeraZone
Zamarreno and Debrenne(1977), Perejón (1986),Moreno-Eiris (1987),Perejón and Moreno-Eiris(1992, 2006), Perejón etal. (2001)
Perejón and Moreno-Eiris(1978), Moreno-Eiris(1987), Perejón andMoreno-Eiris (2006)
oolitic, bioclastic, microbial limestone mounds with Anthomorpha
Atdabanian-Botoman (upperOvetian)
SpainCatalonia
Perejón et al. (1994),Perejón and Moreno-Eiris(2006)
reef 23 × 50 mEpiphyton dominant, Renalcis and less Girvanella, archaeocyathsminor components above small Kalyptrae with large archaeocyathsencrusted by calcimicrobes
Toyonian (mid-upperBilbilian)
SpainCantabrian Mts.
Debrenne and Zamarreno(1975), Álvaro et al.(2000), Perejón andMoreno-Eiris (2003)
Kalyptra 0.8 × 1 mmodular archaeocyath dominant, Renalcis and Girvanella
Botoman (lower MatoppaFormation)
SardiniaMatoppa Valley
Gandin and Debrenne(1984), Debrenne (2007)
discontinuous Kalyptrae, 0.5 × 2 mcore = boundstone: branching or saucer-like archaeocyathsencrusted by Renalcis, Girvanellawave resistant pioneer reefs
Botoman (mid-MatoppaFormation)
SardiniaSan Pietro area
Gandin and Debrenne(1984), Debrenne (2007)
calcimicrobial biostromes Epiphyton dominantminor Renalcis and Tarthinia, archaeocyaths at the periphery
Botoman (mid-MatoppaFormation)
SardiniaGonnesa area(la Sentinella)
Gandin and Debrenne(1984), Gandin et al.(2007), Debrenne (2007)
Debrenne et al. (1980),Gandin and Debrenne(1984), Debrenne (2007)
Girvanella lenticular buildups, massive reefs with cortex of nodularfloatstone with archaeocyathscore: calcimicrobial boundstone Renalcis dominant, Epiphyton,isolated archaeocyathsperiphery: Girvanella dominated boundstone with scatteredarchaeocyaths, skeletal debris
Botoman (lower PuntaManna Formation)
SardiniaPunta Manna
Debrenne et al. (1989a) patch-reef and biostromesbuilder: Girvanella and low-diversity archaeocyath assemblagesback shoal lagoons in oolitic complex
Atdabanian (Puerto BlancoFormation-1)
MexicoSonora
Debrenne et al. (1989b) Type 1: Kalyptra, wave resistant, framework dominated bybranching archaeocyaths, strengthened by encrusting Renalcis,shelf margin
Botoman (Puerto BlancoFormation-2-3)
MexicoSonora
Type 2: patch-reef and biostromesbuilder: Girvanella and low-diversity archaeocyath assemblagesback shoal lagoons in oolitic complex
Botoman (Montenegro-PoletaFormation)
USANevada andCalifornia
Gangloff (1976),Rowland (1984),Rowland and Gangloff(1988)
complex reef H = 65 marchaeocyaths and algal boundstone, cavities with pendant Renalcisreplacement sequence:bioclastic lime-mudstone (stabilization stage)low diversity archaeocyath fauna and thrombolitic fabric(colonization stage)archaeocyath fauna 13% in volume, Renalcis (diversification stage)oligotypic branching archaeocyath 38% in volume (dominationstage)
Late Botoman (Scott CanyonFormation)
USANevadaLander County
Debrenne et al. (1990) Galena Canyon: crusts of Girvanella, Botomaella, Bija + Renalcis,Epiphyton, archaeocyaths, diverse fauna – small cavitiesIron Canyon: Epiphyton, calcimicrobial crusts dominantarchaeocyaths in diverse proportion, cavities
Late Botoman (upperHarkless Formation)
USAWestern Nevada
Savarese and Signor(1989)
complex lenticular, framework = domal Retilamina (archaeocyathdominant) sheltering cavities encrusted by Renalcis4 archaeocyath genera
226 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
Table 1 (Continued)
Stratigraphic distribution Locality Authors Reef types and components
Late Botoman (ShadyDolomite Formation)
USAAppalachesNew Jersey andVirginia
McMenamin et al. (2000) NJ: branching archaeocyaths with exothecal outgrowths,bafflestone, clotted fabric, micritic mudcalm subtidal conditionsVA: bafflestone of branching archaeocyaths associated with otherarchaeocyaths, calcimicrobes, coralomorphs and stromatactiscavitiessubtidal agitated environment
CanadaYukon
Handfield (1971), Read(1980)
kalyptrate reef complex, H = 90 mRenalcis dominant, branching archaeocyaths
Botoman (Nevadella toBonnia-Olenellus zones)
CanadaNW TerritoriesBritish Columbia
Handfield (1971), Stelckand Hedinger (1975),Voronova et al. (1987),Mansy et al. (1993)
archaeocyaths bioconstructions only in Eastern Rocky MountainsTrench, small cups bounded by Renalcis (builder) and someEpiphyton (Regulares dominant on Irregulares)
Late Botoman (ForteauFormation)
CanadaLabrador
James and Kobluk (1978),Debrenne and James(1981)
single Kalyptrae, oligotypic modular archaeocyaths with bindingexothecal structures dominant, Renalcis, Epiphyton = primaryassociation variable within other Kalyptrae in complex reefscavities – boring at topshallow near shore environment, low energy
Lower-Mid Botoman(Wilkawillina Formation)
AustraliaFlinders Ranges
Gravestock (1984), Jamesand Gravestock (1990)
single, 1 m × 1 m; complex, 100 m × 100 mcalcimicrobes dominant – interior platformarchaeocyath dominant + spongiomorphes + rare Renalcis – openshelfRenalcis dominant, rare archaeocyaths – inner shelf-low energyEpiphyton dominant, cryptic archaeocyaths – high energy, shelfmarginGirvanella dominant, Renalcis, Epiphyton, archaeocyaths – openshelf, high energy
Lafuste et al. (1991) single, 3–4 m × 2 marchaeocyaths dominant + tabulate corals, Girvanella + lessfrequent Renalcis and Epiphytonshelf margin, high energy environment
1–3 m × 1–2.5 marchaeocyath rich + calcimicrobesreef-shoalturbulent shallow water
Botoman (Cymbric ValeFormation)
AustraliaNew South WalesMt. Wright
Kruse (1982) 2 m × 2 marchaeocyaths dominant
Botoman (ShackletonLimestone)
TransantarcticMts. Holyoake area
Rees et al. (1989) 0.5–3 m × 0.3–2 msingle to complexthree levels of bioherm complexesreefs with archaeocyath-Epiphyton dominated core associated withothers dominated by calcimicrobes Renalcis, Epiphyton, Girvanella
3
tcw
taWRi
mttlCRih
. Anatomy of the Early Cambrian reefs
As data on Early Cambrian buildups increased, ques-ions arose as to whether the relatively diversified, simplealcimicrobial-archaeocyathan communities could be equatedith the more complex Recent/Present reefs.Studies have been carried out to compare the structures of
rue reefs with those of the Cambrian bioconstructions (Rowland
nd Gangloff, 1988; Wood et al., 1993; Kruse et al., 1995;ood, 1999; Zhuravlev, 2001; Rowland and Shapiro, 2002;owland and Hicks, 2004; Debrenne, 2007). All the authors
nvolved in the study of calcimicrobial-archaeocyathan com-
b(ss
intraplatform open shelf
unities have agreed, except for some minor differences, onheir effective contribution to form a framebuilding that has allhe prerequisites of a reef and in comparison with Recent ana-ogues, ascribed them to tropical warm waters (Debrenne andourjault-Radé, 1994). Nonetheless, the results of analysis ofecent bioaccumulations show that even if the tropical setting
s the privileged factory of carbonate deposits, cooler settings atigher latitudes may produce non-discernible quantities of car-
onates exclusively derived from skeletal particles accumulationJames, 1997). Moreover, temperatures of the water in a deepetting of the tropical zone may equate to the temperatures ofhallow water in higher latitudes. Consequently, the carbonate
A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241 227
F onal dm
dlc
c(
-
-
FmS1–
In the case of the Early Cambrian calcimicrobe-archaeocyathan communities, the problem arises concerningthe palaeoecological behaviour of the dominant calcimicrobes,
ig. 1. Distribution (seen in map and in cross-section) of the different compositiodified after Kruse et al., 1995).
eposits formed in different latitudinal ranges may have a simi-ar composition and may both fall in the field of the cool-waterarbonates.
The Recent cool-water and warm-water benthic, skeletalommunities are characterized by two biological assemblagesJames, 1997):
the warm-water Photozoan Assemblage dominated by lightdependent organisms such as hermatypic corals and greenalgae/calcified phototrophs is commonly associated to non-skeletal allochems;the Heterozoan Assemblage dominated by light independent
benthic organisms such as bryozoans, brachiopods, echino-derms, molluscs and sponges associated with coralline algaethat are prolific in every marine environment where there is: (i)abundant nutrient supply, (ii) shallow cool water or (iii) deeper
2 3 4 51
ig. 2. Solitary or simple, modular archaeocyaths growing in loose, sandy sedi-ent at the periphery of structured mounds (Pestrotsvet Formation, Lena River,iberia; schematic illustration modified after Kruse et al., 1995, fig. 3 pars). Key:– large stick archaeocyaths; 2 – stick and bowl archaeocyaths; 3 – cement; 4Renalcis; 5 – mud.
Farlgc
omains of a multimound bioherm (Pestrotsvet Formation, Lena River, Siberia;
cooler water below the photic zone in the tropical latitudes, toprevent the development of the photozoan assemblages.
ig. 3. An example of mapping on grid squares the different biological andbiotic domains identified on the reef surface (Matoppa Formation, la Sentinellaeef, Sardinia, Italy; modified after Gandin et al., 2007). Key: fA – facies A: pinkaminated limestone; fB – facies B: red marly limestone; fC – facies C: lightrey massive limestone with shelter cavities; fD – facies D: light grey massive,rystalline limestone. Measure of the sides of the grid squares is 30 cm.
228 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
Form
woh(tca
bwmmldt
rdrgrttm
3
Fig. 4. Vertical ecological zonation of a reef complex (Poleta
hich we assume to correspond to the phototroph componentsf the bioconstructions (Figs. 4, 6 and 7), and of the accessoryeterotroph association consisting of sponges/archaeocyathsFigs. 5–7), and a few other taxa such as coralomorphs (Fig. 6E)hat are passively involved in the framebuilding, or as chan-elloriids, trilobites, hyolithids, molluscs, and brachiopods thatppear to have acted commensally (Fig. 8A).
Actually, since the Early Cambrian bioherms were builty low diversity communities and all of the component biotaere extinct before the appearance in Ordovician times, of cli-ate sensible organisms such as bryozoans, green algae and
any other biota, it is difficult, only on the basis of bio-
ogical/ecological affinities, to recognize in the composition,istribution and architecture of buildups, a possible responseo climatic/latitudinal variations.
pt
ation, Nevada; modified after Rowland and Shapiro, 2002).
However, the sedimentological analysis of the differenteef building styles, defined by facies associations and earlyiagenetic features, and of their interrelationships with the sur-ounding sediments, can provide basic information (I) on theeomorphology of the primary depositional setting, since theelative development of the main reef-building components andheir evolution within the reef communities appear to reflecthe dominant physico-chemical factors (II) on the environ-
ent.
.1. Reef building styles and composition
Considering the influence of the depositional setting, it isossible to go further in the study of the ecological proper-ies of archaeocyaths within reefs. The previous studies have
A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241 229
Fig. 5. (A) Small structured mound enclosed in well-bedded platform intermound mudstone (Pestrotsvet Formation, Dvortsy section, Aldan River, Siberia); (B)small pioneer kalyptrate mud mounds made of Epiphyton bushes, growing in tidal channels (Pestrotsvet Formation, Oi Muran section, Lena River, Siberia); (C)mud-supported fabric of an archaeocyath/calcimicrobial mound (Pestrotsvet Formation, Dvortsy section Aldan River, Siberia); (D) Framebuilt mound associated toi stralia( atactiS
eobm(totp
as
sA
ntermound platform bioclastic facies (Aroona section Mount Scott Range, AuForteau Formation, Fox Cove, Labrador); (F) large mud mound-bearing stromardinia, Italy).
stablished that the calcimicrobes interpreted as photoautotrophrganisms acted at the beginning of the Phanerozoic as theasic builders of the pioneer reefs and only in the Tom-otian were joined in the framebuilding by archaeocyaths
Kruse et al., 1996), the first sessile heterotroph metazoan in
he history of the Earth. Their association persisted through-ut the Early Cambrian with only minor variations and whenhe archaeocyaths disappeared, the calcimicrobes resumed andersisted in their mainly solitary activity, eventually associ-
ttts
); (E) Large composite buildup made of stacked lenticular bodies (Kalyptrae)s-like cavities filled with white calcite (Matoppa Formation Funtana Calomba,
ted in the Early Ordovician with other organisms, mainlyponges.
The ecology of Archaeocyaths has been interpreted con-idering the environmental conditions of Recent counterparts.rchaeocyaths were thought to have harboured photosyn-
hetic algal symbionts (Rowland and Savarese, 1990) althoughhis interpretation is hard to support in the case of cryp-ic archaeocyaths (Kruse et al., 1995). Moreover, theirolitary and low integration organization and inferred inter-
230 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
Fig. 6. (A) Assemblage of low diversity solitary archaeocyaths in silty lime mud matrix Punta Manna Formation, Punta Manna section, Sardinia, Italy); (B) largegrowth cavities in an archaeocyath framestone in-filled by geopetally laid lime mud and cement (Pestrotsvet Formation, Byd’yanga section, Lena River, Siberia); (C)Epiphyton dendrolitic framestone with geopetal infilling in the growth cavities (Pestrotsvet Formation, Achchangy-Kyyry-Taas section, Aldan River, Siberia); (D)M uertof olitarm ldan
nmccreR
dc1
odular archaeocyath/dendrolitic Renalcis framestone with geopetal cavities (Pramestone built by modular archaeocyaths and coralomorphs (c), Siberia; (F) satrix: microscopic view of Fig. 5C (Pestrotsvet Formation, Dvortsy section, A
alized soft tissue suggest that they were not photo- orixotrophs (Wood et al., 1993). Evidence from the palaeoe-
ological analysis and sedimentary features suggest they
ould live indifferently on soft or hard substrates, prefer-ing turbid waters high in nutrients and consequently mildlyutrophic or oligotrophic conditions (Wood et al., 1993;iding and Zhuravlev, 1995; Zhuravlev, 2001), in low-latitude
ctp
Blanco Formation, Cerro Rajón section Sonora, Mexico); (E) cement-supportedy archaeocyath cups and associated Epiphyton bushes enclosed in red micriticRiver, Siberia).
eeper waters or in high-latitude shallow, temperate/coolonditions, with normal-to-slightly saline waters (Gandin,987).
The construction style of world-wide Early Cambrian bioac-umulations can be subdivided into six categories according tohe role played by the organism in response to environmentalhysico-chemical conditions.
A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241 231
Fig. 7. (A) Bioclastic accumulation roofed by a large dish-like Anthomorpha cup whose upper wall has been overgrown by a calcimicrobial dendrolitic crust(Matoppa Formation, la Sentinella section, Sardinia; Italy); (B) Calcimicrobial cruststone, composed of superposed crusts of Girvanella, Botomaella or Razumovskiaand cements, developed on top of a large Anthomorpha cup (Matoppa Formation, La Sentinella reef, Sardinia; Italy); (C) Archaeocyath/calcimicrobial frameworkwith structural cavities filled by lime mud (Wilkawillina Limestone, Flinders Range, Australia); (D) cement-supported framestone with well-developed abiotic marinec e bio( ite ce
3
otbac(G
cmciM
ements made of Mg calcite fibres precipitated within the structural cavities of thE) archaeocyatha/calcimicrobial framestone with well-developed crusts of calc
.1.1. Type 1Mud-supported calcimicrobial buildups represented by loaf-
r pillow-shaped mounds (Figs. 2 and 5A–D) called Kalyp-rae (Debrenne, 2007 and references therein) and dominatedy abiotic syn-sedimentary components such as lime-mud
nd/or fine sand. Biotic components are represented by cal-imicrobial dendrolitic frameworks, mostly made of EpiphytonFigs. 5B, 6C and F) and less frequently of Renalcis and/orirvanella, with or without accessory solitary regular archaeo-
bslo
logical framework (Salany Gol Formation, Zavkhan Basin, western Mongolia);ments (Asrir section, Anti Atlas Range, Morocco).
yaths. The growth/shelter cavities are commonly occluded byicritic internal sediment sometimes associated with fibrous
ements (Fig. 6C). Abundance of lime-mud/fine grained sed-ment reinforces the biotic framework (Figs. 6F and 7C).
uds settle in low-energy conditions and record deeper waters,
elow the fair-weather wave-base. Pioneer populations ofolitary (Fig. 6A) or simple modular archaeocyaths couldive in loose, sandy sediment at the immediate peripheryf structured frame-mounds (Figs. 2 and 6A) (e.g., Pardail-
232 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
Fig. 8. (A) Assemblage of commensal biota (chancelloriids, trilobites, hyolithids, molluscs, brachiopods) in the matrix of the youngest, archaeocyath-bearingbuildups (Pestrotsvet Formation, Dvortsy section, Aldan River, Siberia); (B) storm accumulation of skeletal particles preserved as unsorted grainstone (PardailhanF porteR Pestrw ldan RF
h2SIa1
3
ormation, Montagne Noire, France); (C) rippled storm layer made of a mud-supiver, Siberia); (D) unsorted accumulation of bioclastic debris in a storm layer (ith herring-bone cross-lamination (Pestrotsvet Formation, Dvortsy section, Aormation, Dvortsy section, Aldan River, Siberia).
an Formation, Montagne Noire, France: Debrenne et al.,002a; lower Pestrotsvet Formation, Lena and Aldan Rivers,
iberia: Kruse et al., 1995; Matoppa Formation, Sardinia,taly: Gandin, 1987; Wilkawillina Limestone, Flinders Rangesnd Mount Scott Range, Australia: James and Gravestock,990).
daos
d (packstone) bioclastic accumulation (Pestrotsvet Formation, Isit section, Lenaotsvet Formation, Dvortsy section, Aldan River, Siberia); (E) oolitic grainstoneiver, Siberia); (F) microscopic view of the oolitic grainstone of E (Pestrotsvet
.1.2. Type 2Calcimicrobial thrombolitic framestone composed mainly of
ominant Renalcis meadows (Figs. 6D, 7B and C, lower part)ssociated with low diversity clusters of small regular (Fig. 6A)r modular (Fig. 6D) archaeocyaths. Most of the intraskeletalmall cavities are occluded by lime mud or geopetal infilling
A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241 233
Fig. 9. Model of a homoclinal ramp. Early Cambrian buildups related to: the inner section of the ramp with a fringing ooid–shoal complex made of oolitic sandsassociated with biostromal thrombolitic bodies of calcimicrobial framestone and back shoal, low diversity communities of solitary archaeocyaths (A, Debrenne et al.,1 et al.,p chaeo(
(msf
b
991: Tianheban Formation, Yangtze, China, and B, modified after Debrenneart of the ramp with Epiphyton-dominated patch reefs and scattered solitary arC, modified after Gandin, 1987: Matoppa Formation, Sardinia, Italy).
Fig. 6D). The depositional setting of this assemblage, com-
only associated with high-energy oolitic and skeletal/oolitic
hoal complexes (Fig. 8E and F), has been interpreted to haveormed as isolated patch reefs or laterally continuous biostromal
(1M
1989b: Puerto Blanco Formation, Type 2, Sonora, Mexico); the outer, deepercyaths, enclosed in well-bedded open platform lime-mudstone and wackestone
odies (Fig. 9B and C) in rather restricted back-shoal settings
e.g., Punta Manna Formation, Sardinia, Italy: Debrenne et al.,989a; Puerto Blanco Formation, Type 2 buildups, Sonora,exico: Debrenne et al., 1989b; Yukon Territory, Northwestern
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34 A. Gandin, F. Debrenne / P
anada: Read, 1980 and Rowland and Gangloff, 1988; Poletaormation, Nevada, California: Rowland and Shapiro, 2002;ianheban Formation, Yangtze River, China: Debrenne et al.,991 and Gandin and Luchinina, 1993; Wilkawillina Limestone,linders Ranges, Australia: James and Gravestock, 1990; Shack-
.1.3. Type 3Calcimicrobial cruststone, composed of superposed crusts of
irvanella, Botomaella and/or Razumovskia, accessory Renal-is, Epiphyton and cements (Fig. 7B, upper part) with associatedarge, solitary regular, dish- or cup-like archaeocyaths, formsarge shelter cavities (Figs. 7A and B, 10B–E) roofed by coelo-ionts and rim cements and infilled by geopetal muddy sediment,y calcimicrobial framestone or bioclastic packstone. Thus, therchaeocyaths and microbial crusts consortium gave rise, withhe support of cement and mud infillings, to an unusual, ratheresistant framework with a low synoptic relief probably consis-ent with medium energy levels (e.g., Matoppa Formation, Laentinella section, Sardinia, Italy: Gandin et al., 2007; Puertolanco Formation, Sonora, Mexico: Debrenne et al., 1989b; Lasrmitas, Spain: Moreno-Eiris, 1994; Perejón and Moreno-Eiris,006).
.1.4. Type 4Archaeocyath cement-supported framestone composed of
complex intergrowth of modular archaeocyaths, microbesmainly Renalcis) and abundant marine cements (Figs. 4, 6E,D and E) that concurred to build wave-resistant frameworks.hese bioconstructions rarely display a discernible pattern of
nternal organization or evolution (Kruse et al., 1995; Zhuravlev,001). Incipient ecological zonation has been recognized inhe Tommotian of the Siberian Platform (Kruse et al., 1995)hile the only documented example of evident vertical zona-
ion (Fig. 4) has been found in the bioconstructions growing onhe Botoman shallow shelf rimming southwestern North Amer-ca (Rowland and Gangloff, 1988; Rowland and Hicks, 2004).piphyton, coralomorphs (Fig. 6E), radiocyaths, and solitaryrchaeocyaths were common accessories of this community.he latter are found exclusively in cement-supported, domi-antly microbial framestones. This kind of consortium has beennterpreted as living in a photosymbiotic regime and thereforeble to live in warm, nutrient-poor waters in low-latitude seasRowland and Shapiro, 2002). Abiotic marine cements madef well-developed fibres of Mg calcite (Figs. 6E, 7D and E)nd/or aragonite prevail within the structural cavities of theiological framework. They record high energy and evapora-ion of the marine waters and hence depths of deposition abovehe fair-weather wave-base and warm climatic conditions. Thisramework can be equated to that of the wave-resistant moderneefs (e.g., Pestrotsvet Formation, Lena River, Siberian Plat-orm: Kruse et al., 1995; Zavkhan Basin, Mongolia: Kruse
t al., 1996; Scott Canyon Formation, Battle Mountain, Nevada,SA: Debrenne et al., 1990; Poleta Formation, Nevada, USA:owland and Gangloff, 1988; Puerto Blanco Formation, Type 2uildups, Sonora, Mexico: Debrenne et al., 1989b; Wilkawillina
tb
world 19 (2010) 222–241
imestone, Flinders Ranges, Australia: James and Gravestock,990; Matoppa Formation, Matoppa-1 section, Sardinia, Italy:andin and Debrenne, 1984).
.1.5. Type 5Mud mounds with stromatactis-like, irregular spar-filled
oids (Fig. 5F), sometimes roofed by archaeocyath walls or Gir-anella crusts and floored with geopetal internal sediment, cane referred to low-energy, deeper water intrashelf settings bynalogy with the better known Devonian/Carboniferous mud-ominated complexes assumed to have formed in deep marinenvironments (Krause et al., 2004 and references therein) (e.g.,ilkawillina Limestone, Flinders Ranges, Australia: James andravestock, 1990; Issafènes and Amagour sections, Morocco:npublished personal observation; Matoppa Formation, Funtanaalomba section, Sardinia, Italy: Bechstädt et al., 1985; Shack-
.1.6. Type 6Granular accumulations are locally associated to the biocon-
tructions. They are composed of skeletal grainstones (Fig. 8A,and D) derived from inequigranular sands formed by frag-ents of the skeletal components of the bioconstructions
Fig. 8B) and of the associated calcimicrobial tufts and crusts.he bioclasts were cemented by thin marine calcite rimsnd abundant freshwater equant calcite. This fabric suggestsigh-energy, wave-swept settings around biohermal frameworkshat were partially or totally destroyed by storms (e.g., Scottanyon Formation, Battle Mountain, Nevada, USA: Debrennet al., 1990; Pardailhan Formation, Montagne Noire, France:ebrenne et al., 2002a; Wilkawillina Limestone, Flindersanges, Australia: James and Gravestock, 1990).
Oolitic grainstones and oncolitic rudstones, often containingfair amount of skeletal particles mainly represented by echin-derm ossicles and cups of archaeocyaths, formed sand wavesnd shoals (Fig. 8C and E), which concurred to the establishmentf relatively restricted backshoal environments suitable for theevelopment of thrombolitic biostromes.
The Early Cambrian first consortium of metazoans and pho-oautotroph calcimicrobes, defined by the types of associatedacies and by the early diagenetic features, was able to buildeefs in a variety of shallow-marine settings, whose latitudinalange has been related to the tropical zone, inferred to be com-rised like the present one, between 30◦N and 30◦S (Rowlandnd Shapiro, 2002). However, in the Recent bioaccumulations,ifferent building communities and different building architec-ures have been observed to develop in different geographicettings: the Phototroph assemblages flourishing in the lower,ropical latitudes while the Heterotroph assemblages living atigher latitudes in the northern and southern hemispheres.
.2. Physico-chemical factors of the reef environment
Besides the ecologic and physico-chemical factors con-rolling the carbonate sedimentation, the development of theioconstructions is also a function of the morphology of the
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epositional setting, in turn symptomatic of specific geodynamicegimes. Thus, the architecture and structure of the bioconstruc-ions reflect not only on temperature, energy and depth of theea waters as described above, but also on the morphology ofhe shelf and its latitudinal position.
Phanerozoic shelves and carbonate platforms display vari-ble morphologies, gradients, and consequently depths that areonstrained by the geologic nature of the basin and its genesis.
The results of the analysis of the sedimentological and eco-ogical features of most of the Early Cambrian bioaccumulationstill preserved in the present-world continental blocks imply dif-erent physico-chemical depositional conditions suggestive ofhe specific morphologies of the carbonate platform. As a mat-er of fact, it appears, that as it happens today, also in the past,he reef architecture was controlled by the levels of energy andonsequently by the morphology of the carbonate platforms.
The best preserved and studied, Early Cambrian carbonateuccessions are found in Siberia (Kruse et al., 1995), Southernustralia (James and Gravestock, 1990), and western and north-
astern North America (James and Debrenne, 1980; Rowlandnd Gangloff, 1988; Debrenne et al., 1989b). In the other regions,ectonics affected the old Palaeozoic rocks so badly sometimeshat sporadically good outcrops depend on fortuitous structuralonditions and the reconstruction of the platform complex isomehow conjectural (e.g., Montagne Noire, Debrenne et al.,002a; Sardinia, Gandin et al., 2007). Nevertheless, these suc-essions represent wide and complex carbonate platforms wheren array of different microenvironments resulted in a variety ofioconstructions, which developed simultaneously or evolved inime.
The first reefs, a consortium of calcimicrobes and metazoansominated by archaeocyath porifera, appeared in Siberia duringhe Tommotian, as individual metre-scale mounds (Kalyptra,ig. 5A, C and D), later stacked to form multi-mound biohermsFig. 5E). They spread in the adjacent continents during thetdabanian and reached a maximum of diffusion during theotoman, building much larger edifices sometimes showing arude ecological zonation (Fig. 8), but still composed of theasic building Kalyptra blocks. At the end of the Early Cam-rian, during the Toyonian, when the archaeocyaths were in fullecline, the reefs reached the northeastern coasts of North Amer-ca, their architecture still displaying the same basic structure ofhe Tommotian ones of Siberia.
The distribution in space and time of archaeocyath-alcimicrobe buildups reflects the evolution of the archaeocyathsith a peak in the Botoman Stage when wide shelves withniform low-angle inclinations on the margins of very flat land-asses located in the tropical zone, apparently provided the
ptimal conditions of development. The drastic decrease ofrchaeocyath contribution to the buildups occurred during theoyonian Stage when the beginning of the drifting towards
he southern Pole and a consequent more abrupt morphologyf the shelves should have led to adverse conditions of life.
onetheless, new forms persisted during the Middle and even
he Late Cambrian in Antarctica, the only continent set in lowatitudes. During Middle Cambrian, the remaining carbonatelatforms were located in high latitudes and inhabited by pho-
Si1(
world 19 (2010) 222–241 235
oautotroph microbes. They were probably the only calcareousecreting organisms able to survive the Early/Middle Cambrianooling crisis. This biogeographic evolution is also supportedy the palaeogeographic and palaeomagnetic reconstruction ofhe relative position of continental blocks, epeiric basins, anderioceanic/pericontinental platforms, at the end of the Earlyambrian (Courjault-Radé et al., 1992; Rowland and Shapiro,002).
. Models of carbonate platforms and related Earlyambrian bioaccumulations
Given the abiotic and biotic composition as well as the archi-ecture of the Early Cambrian bioconstructions, it appears thatarbonate sedimentation developed mostly on shelves with low-ngle depositional profiles. The results of the analysis of theedimentary architecture of the known models of carbonate plat-orms suggest that their different depositional profiles resultostly from the interaction of morphology/geodynamic regime,
atitude/climate and biotic, and abiotic production of carbon-te sediment, in turn controlled by genetic factors such as theydraulic energy and the light requirements of the existing biotaRead, 1985; Barnaby and Read, 1990; James, 1997; Pomar,001). The dominance during Early Cambrian times of muddyarbonate sediments and of oligotrophic or photo-independentiota in all water depths supports the inference that most of theime-mud rich bioaccumulations grew in deeper low-energy set-ings contributing to the development of homoclinal to distallyteepened ramps and that only locally, cement-rich framestoneseveloped on and built up rimmed shelves.
The combined effects of inherited topography, tectonic activ-ty, and sea-level changes appear to control the development ofhe rim relief that can evolve into a barrier reef system whenigh-energy conditions support the growth of rigid framework-uilding biota (robust skeletons and encrusting organism) andbiotic calcite cements.
The Early Cambrian bioconstructions represented by smallioneer, calcimicrobial buildups (Kalyptrae) associated withiostromal and/or oolitic shoals complexes showing evidencef a general low level of energy, can be related to a fring-ng ooid–shoal complex (Read, 1985) in the shallower part ofttached carbonate platforms, developed in intracratonic basinsr oceanic shelves of very flat landmasses that can be equatedith the very low-angle profile, without slope, of a homoclinal
amp. Both kalyptrate bodies and biostromal constructions con-ist of silty-mud to lime-mud supported dendrolitic frameworksominated respectively by Epiphyton or Renalcis and associatedith low diversity solitary archaeocyath assemblages. Pioneeralyptra buildups (Type 1, Figs. 9, 10 and 11) occur in thereat Basin, California (Rowland and Gangloff, 1988), Siberia
Kruse et al., 1995); Forteau Formation, Labrador (Debrenne andames, 1981), and Montagne Noire (Debrenne et al., 2002a).arger, mud-dominated Epiphyton-built mounds occurring in
ardinia, Matoppa Formation (Gandin and Debrenne, 1984) and
n the Flinders Ranges Shelf, Australia (James and Gravestock,990), can be ascribed to the deeper, outer part of the rampFig. 9).
236 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
Fig. 10. Model of a distally steepened ramp. Early Cambrian buildups related to: the inner part of the ramp: small pioneer bodies (Kalyptrae) built up on a quartz-sands A, afta l crusP ndin e
rmbd
a
ubstrate, by dendrolitic Epiphyton/Girvanella frameworks in silty lime mud (fter James and Kobluk, 1978); the steeper ramp margin: complex calcimicrobiaerejón and Moreno-Eiris, 2006, Cerro de Las Ermitas section, and D, after Ga
Larger, oolitic-sheltered lagoonal complexes made of patch
eefs or thrombolitic framestone and/or calcimicrobial biostro-al bodies (Type 2, Fig. 9), which can be related to a
arrier ooid–shoal complex on a ramp (Read, 1985), have beenescribed in the Great Basin, California, and Nevada (Rowland
FPTm
er Debrenne et al., 2002a: Pardailhan Formation, Montagne Noire, France; B,tstone bioherms with low synoptic relief and shelter cavities (C, modified aftert al., 2007, Matoppa Formation, la Sentinella reef, Sardinia, Italy).
nd Gangloff, 1988; Rowland and Shapiro, 2002); Puerto Blanco
ormation, Sonora, Type 2 buildups (Debrenne et al., 1989b);unta Manna Formation, Sardinia (Debrenne et al., 1989a);ransantarctic Mountains (Rees et al., 1989); Tianheban For-ation, Yangtze Platform, China (Debrenne et al., 1991) and
A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241 237
F d to:b emena dified
i(FlieM
bTm
ig. 11. Model of a distally rimmed platform. Early Cambrian buildups relateioherms and archaeocyath framestone supported by abundant marine fibrous cnd Rowland and Gangloff, 1988); B, the Flinders Ranges Shelf, Australia (mo
n the Wirrealpa Limestone, Flinders Ranges Shelf, AustraliaKruse, 1991). Calcimicrobial cruststone bioherms (Type 3,ig. 10) composed of superposed calcimicrobial crusts and
arge saucer-like solitary archaeocyaths have been recognizedn La Sentinella reef, Matoppa Formation, Sardinia (Gandint al., 2007), in the Puerto Blanco Formation, Type 2 buildups,exico (Debrenne et al., 1989b) and illustrated in Las Ermitas
rr
m
multi-stored bioherms built on the shelf margin by calcimicrobial/Epiphytonts: A, the “Great Siberian Barrier Complex” (modified after Kruse et al., 1996after Rowland and Shapiro, 2002 and James and Gravestock, 1990).
ioconstructions of Spain (Perejón and Moreno-Eiris, 2006).hey show a low but conspicuous synoptic relief suggestingild energy conditions of the depositional setting that can be
elated to the gentle marginal break of a distally steepenedamp.
Composite lenticular bodies, stacked to form multi-storiedound bioherms (Type 4, Fig. 11), concurred to form a
238 A. Gandin, F. Debrenne / Palaeoworld 19 (2010) 222–241
F rian b( indersc on the
bt1tmiafad
pcopai
ig. 12. Model of an isolated platform/intrashelf basin complex. Early Cambmodified after Rowland and Shapiro, 2002 and James and Gravestock, 1990, Flalcimicrobial/Epiphyton bioherms on the seaward margin and by oolitic shoal
arrier–reef complex, the first on the history of the Earth, calledhe “Great Siberian Barrier Complex” (Rowland and Gangloff,988; Kruse et al., 1995). It grew in warm climate latitudes, onhe marginal part of a platform with steeper slope and prominent
argins and higher energy gradients that over time developednto a distally rimmed platform. Microbially bound bioherms
nd associated modular/branched archaeocyaths provided a rigidramework supported by abundant marine fibrous cements thatttests the high energy and well-oxygenated depositional con-itions of the Tommotian/Atdabanian Siberian Platform. The
Ft11
uildups related to: A, the intrashelf basin: stromatactis-bearing mud moundsRanges Shelf, Australia); B, the Bahamian-type isolated platforms rimmed bylandward side (modified after Gandin, 1987, Gonnesa Group, Sardinia, Italy).
atchy distribution of the bioconstruction did not restrict the freeirculation of seawater so that open carbonate platforms devel-ped in the wide interior shelf where lower energy conditionsrevail, well-bedded mudstone/wackestone were occasionallyffected by storm-induced, mass sediment/bioclastic rework-ng. Similar constructions are extensively represented in the
linders Ranges Shelf, Australia (James and Gravestock, 1990);
he Zavkhan Basin, Mongolia (Wood et al., 1993; Kruse et al.,996); Forteau Formation, Labrador (Debrenne and James,981) where rubbles of the broken parts of the modular/branched
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uilders were accumulated in unsorted breccias at the base ofhe slope.
The Epiphyton-dominated, calcimicrobial mounds, andolitic accumulations described in the Toyonian of SardiniaGonnesa Formation) have been interpreted (Debrenne andandin, 1985; Cocozza and Gandin, 1990) as developed on
he rifted passive margins of continental blocks resulting fromtensional tectonic regime that fostered the formation of
ahamian-type system of isolated platforms (Type 1, Fig. 12).hey are characterized by a slope gradient higher than that of theomoclinal ramps and by high-energy margins where skeletaleefs grow on the seaward side of the platform, supported by ateady supply of nutrients provided by upwelling currents, whilen the opposite side only oolitic shoals develop. Similar condi-ions are also reported from the Flinders Ranges Shelf, AustraliaJames and Gravestock, 1990) and probably from Buelna For-ation in Mexico (Debrenne et al., 1989b).Large mud mounds with flat-floored, stromatactis-like
avities occluded by several generations of marine and/or non-arine calcite cements (Type 5, Fig. 12) have been reported from
he Flinders Ranges Shelf, Australia (James and Gravestock,990), from Morocco (Issafènes and Amagour red limestone,ersonal observations), and from Sardinia (Matoppa Formation,untana Calomba section, Bechstädt et al., 1985). They can beelated to deeper conditions in intrashelf basins where the low-nergy of the waters preserves and promotes the deposition ofime mud, the major component of the mounds.
Granular accumulations of skeletal sands/grainstone (Type), apparently unrelated to bioconstructions but evidentlyerived from rarely preserved calcimicrobial/archaeocyathounds, have been observed in (i) Nevada olistoliths associ-
ted with Botoman-Toyonian reefs (Battle Mountains, Nevada,ebrenne et al., 1990); (ii) in the Toyonian deposits of Siberia
Elanka Section, Lena River, personal observations); and (iii)n the Montagne Noire, Pardailhan Formation, Debrenne et al.,002a). Their occurrence suggests depositional conditions thatan be related to high-energy ramps and/or open shelveswept by strong wave and current flows, and possibly to lessarm/cooler marine waters.
. Concluding remarks
The oldest bioconstructions on the Earth in which metazoansith a rigid mineralised skeleton are involved were built in Earlyambrian by photoautotroph organisms, mainly cyanobacte-
ia, able to precipitate in the outer cellular wall a mineralisedoating made of micritic calcite, and by archaeocyaths, suspen-ion feeder, sessile heterozoan organisms representing an extinctlass of Porifera.
The depositional features and the different styles of reefuilding appear to reflect the ecologic conditions of theicrobial-archaeocyath communities and the highly diversified
hysico-chemical factors controlling the carbonate sedimenta-
ion. A direct correlation between the physico-chemical factorsf deposition and the structural architecture of the buildupsesults from the analysis of most of the Early Cambrian bioac-umulations exposed in the present continental blocks.
vPtT
world 19 (2010) 222–241 239
Thus, the architecture and structure of the bioaccumulationsan be related to the combined effects of energy and depth ofhe sea waters controlled by the morphology of the shelf, andf the temperature and nutrient availability controlled by theiratitudinal collocation.
Consequently, different biohermal communities and archi-ectures of the buildups reflect the physiography of the primaryepositional setting. They all developed at photic and shallowub-photic depths on low-angle ramps or distally rimmed plat-orms of pericontinental/epeiric basins:
mud supported simple to compound mounds, locally withstromatactis-like cavities, developed in subtidal low-energyramp/intraplatform settings;dendrolitic bioherms and crustose buildups with large sheltercavities and low synoptic relief grew on medium-energy rampmargins;cement-supported skeletal reefs with wave-resistant frame-works often associated to oolitic shoals were located onhigh-energy platform rims;bioclastic sands were accumulated by storm currents on theshelves.
Traditionally, all archaeocyath-bearing bioaccumulationsave been generically considered of reefal origins and for com-arison with recent analogues, ascribed to tropical warm waters.owever, the architecture of the buildups varies with their spatialistribution, suggesting that their development was affected notnly by the physiography of the depositional setting but also byocal climatic conditions constrained by the latitudinal positionf the continental blocks.
The cement/skeletal constructions corresponding to wave-esistant reefs developed in arid zones in tropical latitudes,orming barrier reef complexes. Dendrolitic and crustoseuildups with large shelter cavities and low synoptic reliefrew in medium energy conditions on ramp margins probablyn intermediate warm/temperate latitudes. The mud-supporteduildups, the stromatactis-like mounds typical of subtidal, low-nergy cooler settings, and the bioclastic accumulations relatedo storm events were mainly established in higher latitudes.hus, most of the Early Cambrian bioaccumulations can be con-idered as true bioconstructions, but only some of them can beelated to wave-resistant reefs.
Moreover, reconstruction of the Early Cambrian palaeo-eography based on palaeomagnetic data suggests a southernistribution of the continental masses and basins that during theotoman, promoted the maximum diffusion of the archaeocyathommunities and led to the development of a variety of reefs.
cknowledgements
We would like to thank reviewers Elena Moreno-Eiris andteve Kershaw for constructive criticism that improved the final
ersion of this paper. We appreciate Dr. Olga Kossovaya’s androf. Ian D. Somerville’s support during the editorial stages of
he paper. We are grateful for the assistance provided by Barbaraerrosi in the preparation of figures and drawings.
2 alaeo
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40 A. Gandin, F. Debrenne / P
eferences
lvaro, J.J., Debrenne, F., 2007. Giant Lower-Cambrian Archaeocyathan-Microbial Reef Complexes, Mediterranean region. In: Vennin, E., Aretz,M., Boulvain, F., Munnecke, A. (Eds.), Facies from Paleozoic Reefs andBioaccumulations. Publication of Muséum National d’Histoire Naturelle,Springler-Verlag, Berlin, pp. 45–48.
lvaro, J.J., Vennin, E., Moreno-Eiris, E., Perejón, A., Bechstädt, T., 2000.Sedimentary patterns across the Lower-Middle Cambrian transition in theEsla nappe (Cantabrian Mountains, northern Spain). Sedimentary Geology137, 43–61.
arnaby, R.J., Read, J.F., 1990. Carbonate ramp to rimmed shelf evolution:Lower to Middle Cambrian continental margin Virginia Appalachians. Geo-logical Society America Bulletin 102, 391–404.
echstädt, T., Boni, M., Selg, M., 1985. The Lower Cambrian of SW Sar-dinia: from a clastic tidal shelf to an isolated carbonate platform. Facies12, 113–140.
amoin, G., Debrenne, F., Gandin, A., 1989. Premières images des commu-nautés microbiennes dans les écosystémes cambriens. Comptes Rendus del’Académie des sciences, Paris 308 (2), 1451–1458.
ocozza, T., Gandin, A., 1990. Early rifting deposition: examples from car-bonate sequences of Sardinia (Cambrian) and Tuscany (Triassic-Jurassic)Italy. Analogous tectono-sedimentary and climatic situation. InternationalAssociation Sedimentologists Special Publication 9, 9–37.
ourjault-Radé, P., Debrenne, F., Gandin, A., 1992. Palaeogeographic andgeodynamic evolution of the Gondwana continental margins during theCambrian. Terra Nova 4, 657–667.
ebrenne, F., 1958. Sur les Archaeocyatha du Cambrien de Carteret (Manche).Société géologique de France Bulletin 6 (8), 615–620.
ebrenne, F., 1959. Récifs, biohermes ou bancs fossiliféres d’Archéocyatha.Société géologique de France Bulletin 7 (1), 393–395.
ebrenne, F., 1975. Formations organogènes du Cambrien inférieur du Maroc.In: Sokolov, B.S. (Ed.), Drevnie Cnidaria Tom II. Institut Geol. Geofiz.Sibirsk otdtel, 202. AN SSSR, Novosibirsk, pp. 19–24.
ebrenne, F., Courjault-Radé, P., 1994. Répartition paléogéographique desarchéocyathes et délimitation des zones intertropicales au Cambrieninférieur. Société géologique de France Bulletin 165 (5), 459–467.
ebrenne, F., Debrenne, M., 1995. Archaeocyaths of the Lower Cambrian ofMorocco. Beringeria Special Issue 2, 121–145.
ebrenne, F., Gandin, A., 1985. La Formation de Gonnesa (Cambrien, SWSardaigne): biostratigraphie, paléogéographie, paléoécologie des archéocy-athes. Société géologique de France Bulletin 8, 1 (4), 531–540.
ebrenne, F., James, N.P., 1981. Reef-associated archaeocyathans from theLower Cambrian of Labrador and Newfoundland. Palaeontology 24,343–378.
ebrenne, F., Vacelet, J., 1984. Archaeocyatha: is the sponge model consis-tent with their structural organisation? Palaeontographica Americana 54,358–369.
ebrenne, F., Zamarreno, I., 1975. Sur la faune d’archéocyathes de la formationde Vegadeo et leur rapport avec la distribution des faciès carbonatés dans leNW de l’Espagne. Breviora Geologica Asturica 19 (2), 17–27.
ebrenne, F., Zhuravlev, A., 1996. Archaeocyatha, palaeoecology: a Cambriansessile fauna. Bollettino Società Paleontologica Italiana, Special Volume 3,77–85.
ebrenne, F., Gandin, A., Simone, L., 1980. Studio sedimentologico comparatodi tre “lenti” calcaree ad archeociati dell’Iglesiente e Sulcis (Sardegna Sud-occidentale). Memorie della Società Geologica Italiana 20, 379–393.
ebrenne, F., Gandin, A., Pillola, G.L., 1989a. Biostratigraphy and depositionalsetting of Punta Manna Member type-section (Nebida Formation, LowerCambrian, SW Sardinia Italy). Rivista Italiana Paleontologia e Stratigrafia94 (4), 483–514.
ebrenne, F., Gandin, A., Rowland, S.M., 1989b. Lower Cambrian bioconstruc-tions in northwestern Mexico (Sonora), Depositional setting, paleoecologyand systematics of archaeocyaths. Géobios 22, 137–195.
ebrenne, F., Gandin, A., Gangloff, R.A., 1990. Analyse sédimentologiqueet paléontologique des calcaires organogènes du Cambrien inférieur de
K
world 19 (2010) 222–241
Battle Mountain (Nevada U.S.A.). Annales de Paléontologie (Vertébrés-Invertébrés) 76, 73–119.
ebrenne, F., Gandin, A., Zhuravlev, A., 1991. Paleoecological and sedimento-logical remarks on some Lower Cambrian sediments of the Yangtze Platform(China). Société géologique de France Bulletin 162, 575–583.
ebrenne, F., Debrenne, M., Faure-Muret, A., 1992. Faunes d’Archéocyathesde l’Anti-Atlas occidental (bordures Nord et Sud) et du Haut-Atlas occiden-tal Cambrien inférieur, Maroc. Géologie Méditerranéenne (1990) 17 (3–4),177–211.
ebrenne, F., Gandin, A., Courjault-Radé, P., 2002a. Facies and depositionalsetting of the Lower Cambrian archaeocyath-bearing limestones of South-ern Montagne Noire (Massif central France). Societé gèologique de FranceBulletin 173 (6), 533–546.
ebrenne, F., Zhuravlev, A.Yu., Kruse, P.D., 2002b. Class Archaeocyatha Borne-mann 1884. In: Hooper, J., van Soest, R. (Eds.), Systema Porifera: A Guideto the Classification of Sponges 2. Kluwer Academic/Plenum Publishers,pp. 1539–1699.
oré, F., 1972. La transgression majeure du Paléozoïque inférieur dans leNordEst du Massif Armoricain. Société géologique de France Bulletin 7(14), 79–93.
rosdova, N.A., 1980. Algae in Lower Cambrian organic mounds of west-ern Mongolia. Sovmestnaya Sovetsko-Mongol’skaya PaleontologicheskayaEkspeditsiya, Moscow 18, 137 pp. (in Russian).
andin, A., 1987. Depositional and paleogeographic evolution of the Cambrianin south-western Sardinia. In: Sassi, F.P., Bourrouilh, R. (Eds.), IGCP Project5. Newsletter 7, pp. 151–166.
andin, A., Debrenne, F., 1984. Lower Cambrian Bioconstructions in South-western Sardinia (Italy). Géobios Mémoire Speciale 8, 231–240.
andin, A., Luchinina, V., 1993. Occurrence and environmental meaningof the Early Cambrian calcareous algae of the Tianheban Formation ofChina(Yangtze Area). In: Barattolo, F., De Castro, P., Parente, M. (Eds.),Studies on Fossil Benthic Algae. Bollettino Società Paleontologica Italiana,Special Volume 1, pp. 211–217.
andin, A., Debrenne, F., Debrenne, M., 2007. Anatomy of the Early Cam-brian ‘La Sentinella’ reef complex, Serra Scoris, SW Sardinia Italy. In:Álvaro, J.J., Aretz, M., Boulvain, F., Munnecke, A., Vachard, D., Vennin,E. (Eds.), Palaeozoic Reefs and Bioaccumulations: Climatic and Evolu-tionary Controls. Geological Society London, Special Publications 275,pp. 29–50.
angloff, R.A., 1976. Archaeocyatha of eastern California and western Nevada.In: Moore, J.N., Fritsche, A.E. (Eds.), Depositional Environments of LowerPaleozoic Rocks in the White-Inyo Mountains, Inyo County, Pacific CoastPaleogeography Field Guide I, Pacific Section. SEPM, Tulsa, pp. 19–29.
ravestock, D.I., 1984. Archaeocyatha from lower parts of the Lower Cam-brian carbonate sequence in South Australia. Association of AustralasianPalaeontologists Memoir 2, 139 pp.
andfield, R.C., 1971. Archaeocyatha from the Mackenzie and CassiarMountains, Northwest Territories, Yukon Territory and British Columbia.Geological Survey of Canada Bulletin 201, 1–119.
House, Moscow, pp. 31–109 (in Russian).Zhuravleva, I.T., Zelenov, K.K., 1955. Bioherms from the Pestrotsvet Formation
A. Gandin, F. Debrenne / P
ruse, P.D., 1982. Archaeocyathan biostratigraphy of the Gnalta Group at Mt.Wright, New South Wales. Palaeontographica A 177, 129–212.
ruse, P.D., 1991. Cyanobacterial-archaeocyathan-radiocyathan bioherms in theWirrealpa Limestone of South Australia. Canadian Journal of Earth Sciences28, 601–615.
ruse, P.D., West, P.W., 1980. Archaeocyatha of the Amadeus and GeorginaBasins. BMR Journal of Australian Geology and Geophysics 5, 165–181.
ruse, P.D., Zhuravlev, A.Yu., James, N.P., 1995. Primordial metazoan-calcimicrobial reefs: Tommotian (Early Cambrian) of the Siberian Platform.Palaios 10 (4), 291–321.
ruse, P.D., Gandin, A., Debrenne, F., Wood, R., 1996. Early Cambrian biocon-structions in the Zavkhan Basin of western Mongolia. Geological Magazine133, 429–444.
afuste, J., Debrenne, F., Gandin, A., Gravestock, D., 1991. The oldest Tabulatecoral and the associated archaeocyatha, Lower Cambrian, Flinders Ranges,South Australia. Géobios 24 (6), 697–718.
ansy, J.L., Debrenne, F., Zhuravlev, A.Yu., 1993. Calcaires à archéocy-athes du Cambrien Inférieur du nord de la Colombie Britannique (Canada)Implications paléogéographiques et précisions sur l’extension du continentAméricano-Koryakien. Géobios 26, 643–683.
cMenamin, M.A.S., Debrenne, F., Zhuravlev, A.Yu., 2000. Early CambrianAppalachian archaeocyaths: further age constraints from the fauna of NewJersey and Virginia U.S.A. Géobios 33, 693–708.
oreno-Eiris, E., 1987. Los monticulos arrecifales de Algas y Arqueociatos delCambrico Inferior de Sierra Morena: Estratigrafia y Facies. 127. IV. Bioes-tratigrafia y Sistemàtica de los Arqueociatos. Boletin Geologico y Minero98 (3–6), 729–779.
oreno-Eiris, E., 1994. Lower Cambrian reef mounds of Sierra Morena (SWSpain). Courier Forschungs-Institut Senckenberg 172, 185–192.
erejón, A., 1986. Biostratigrafia de los Arqueociatos en Espana. Cuadernos deGeologia Iberica 9 (1984), 213–266.
erejón, A., Moreno-Eiris, E., 1978. Nuevos datos sobre la fauna de Arqueoci-atos y las facies carbonatadas de la serie de Los Campillos (Urda, Montesde Toledo orientales). Estudios Geològicos 34, 193–204.
erejón, A., Moreno-Eiris, E., 1992. Paleozoico inferior de Ossa Morena. In:Gutierez Marco, J.G., Saavedra, J., Rabano, I. (Eds.), Paleozoico Inferiorde IberoAmerica, chapter 32. Universidad de Extremadura, Merida, pp.557–565.
erejón, A., Moreno-Eiris, E., 2003. Arqueociatos del Bilbiense (Cambrico infe-rior) del manto del Esla, Cordillera Cantabrica, Norte de Espana. Boletin dela Real Sociedad Espanola de Historia Natural (Sección Geológica) 98 (1–4),51–71.
erejón, A., Moreno-Eiris, E., 2006. Arqueociatos de Espana: Bioconstruc-ciones y puesta al dia de la sistematica y la bioestratigrafia. Boletin de laReal Sociedad Espanola de Historia Natural (Sección Geológica) 101 (1–4),105–145.
erejón, A., MorenoEiris, E., Abad, A., 1994. Monticulos de arqueociatos ycalcimicrobos del Cambrico inferior de Terrades, Gerona (Pirineo orientalEspana). Boletin de la Real Sociedad Espanola de Historia Natural (SecciónGeológica) 89 (14), 55–95.
erejón, A., Moreno-Eiris, E., Menendez, S., 2001. Las sucesiones estratigrafi-cas con arqueociatos y calcimicrobios del Cambrico inferior de la PeninsulaIberica. In: Gamez, G.A., Vintaned, G.A., Linan, E. (Eds.), Memorias de laVII Jornadas Aragonesas de Paleontologia. Institución Fernando el Católico,pp. 61–83.
omar, L., 2001. Types of carbonate platforms: a genetic approach. BasinResearch 13, 313–334.
ead, J.C., 1985. Carbonate platform facies models. American Association ofPetroleum Geologists Bulletin 69, 1–21.
ees, M.N., Pratt, B.R., Rowell, A.J., 1989. Early Cambrian reef complexes andassociated lithofacies of the Shackleton Limestone, Transantarctic Moun-
tains. Sedimentology 36, 341–361.
iding, R., Zhuravlev, A.Yu., 1995. Structure and diversity of oldest sponge-microbe reefs: Lower Cambrian, Aldan River Siberia. Geology 23 (7),649–652.
world 19 (2010) 222–241 241
owland, S.M., 1984. Were there framework reefs in the Cambrian? Geology12 (7), 181–183.
owland, S.M., Gangloff, R.A., 1988. Structure and paleoecology of LowerCambrian reefs. Palaios 3, 111–135.
owland, S.M., Hicks, M., 2004. The Early Cambrian experiment inreef-building by metazoans. In: Lipps, J.H., Waggoner, B.M. (Eds.),Neoproterozoic-Cambrian Biological Revolutions. The PaleontologicalSociety Papers 10, pp. 107–130.
owland, S.M., Savarese, M., 1990. Algal symbiosis in Archaeocyatha. In:Repina, L.N., Zhuravlev, A.Yu. (Eds.), Third International Symposium onthe Cambrian System, Novosibirsk. Abstracts. IGIG SOAN, Novosibirsk,p. 52.
owland, S.M., Shapiro, R.S., 2002. Reef patterns and environmental influencesin the Cambrian and earliest Ordovician. SEPM Special Publication 72,95–128.
avarese, M., Signor, P.W., 1989. New Archaeocyathan occurrences in TheUpper Harkless Formation (Lower Cambrian of Western Nevada). JournalPaleontology 63 (5), 539–548.
avarese, M., Mount, J.F., Sorauf, J.E., Bucklin, L., 1993. Paleobiologic andpaleoenvironmental context of coral-bearing Early Cambrian reefs: impli-cations for Phanerozoic reef development. Geology 21, 917–920.
telck, C.R., Hedinger, A.S., 1975. Archaeocyathids and the Lower Cambriancontinental shelf of the Canadian Cordillera. Canadian Journal of EarthSciences 12, 2014–2020.
oronin, Yu.I., Drozdova, N.A., 1976. Archaeocyathan-algal ancient com-plexes of Western-Mongolia. In: Kramarenko, N.N. (Ed.), Paleontologyand Biostratigraphy of Mongolia. Trudy Sovtesnoy Sovietsko-Mongol’skoypaleontologycheskoy ekspeditsii 3. Nauka, Moscow, pp. 291–297(in Russian).
oronova, L.G., Drozdova, N.V., Esakova, E., Zhegallo, A., Zhuravlev,A.Yu., Rozanov, A.Yu., Sayutina, T.A., Ushatinskaya, G.T., 1987. LowerCambrian fossils of the Mackenzie Mountains (Canada). Trudy Pale-ontologicheskogo Instituta Akademii Nauk SSSR Moscow 224, 88 pp.(in Russian).
ood, R., 1999. Reef Evolution. Oxford University Press, Oxford, 414 pp.ood, R.A., Zhuravlev, A.Yu., Chimed Tseren, A., 1993. The ecology of Lower
Cambrian buildups from Zuune Arts Mongolia: implications for early meta-zoan reef evolution. Sedimentology 40, 829–858.
uan, K.X., Zhu, M.Y., Zhang, J.M., Van Iten, H., 2001. Biostratigraphy ofarchaeocyathan horizons in the Lower Cambrian Fucheng section SouthShaanxi Province: implications for regional correlations and archaeocyathanevolution. Supplement: the Cambrian of South China. Acta PalaeontologicaSinica 4, 115–129.
adorozhnaya, J.M., 1974. Lower Cambrian bioconstructions from the east-ern part of the AltaySayan Fold Belt. Institut Geologii i GeofizikiSibirskoe Otdelenie Akademiya Nauk SSSR Trudy 84, 159–186(in Russian).
amarreno, I., Debrenne, F., 1977. Sédimentologie et biologie des construc-tions organogènes du Cambrien inférieur du Sud de l’Espagne. Bureau deRecherches Géologiques et Minières, Mémoire 89, 49–61.
huravlev, A.Yu., 2001. Paleoecology of Cambrian reef ecosystems. In: StanleyJr., G.D. (Ed.), The History and Sedimentology of Ancient Reef Systems.Kluwer Academic/Plenum Publishers, pp. 121–157.
huravleva, I.T., 1960. Archaeocyaths of the Siberian Platform. AkademiyaNauk SSSR, Moscow, 344 pp. (in Russian).
huravleva, I.T., 1966. Early Cambrian Organogenous Buildups on the Territoryof the Siberian Platform. Organism and Environment in the Geological Past.Nauka Publishing House, Moscow, pp. 61–84 (in Russian).
huravleva, I.T., 1972. Early Cambrian facies assemblages of archaeocyaths(Lena River, middle reaches). In: Zhuravleva, I.T. (Ed.), Problems of LowerCambrian Biostratigraphy and Paleontology in Siberia. Nauka Publishing
of the Lena River. In: Sarycheva, T.G. (Ed.), Materials on the PalaeozoicFauna and Flora of Siberia. Paleontologicheskiy Institut Akademiya NaukSSSR, Moscow 56, pp. 57–78 (in Russian).
