Facies development of a Late Ordovician mixed carbonate-siliciclastic ramp proximal to the developing Taconic orogen: Lourdes Formation, Newfoundland, Canada

The Upper Ordovician (late Whiterockian to Mohawkian) Lourdes Formation represents a narrow (tens of kilometers), short-lived [∼5–7 million years (my)], open-ocean (high-energy) mixed siliciclastic-carbonate ramp that onlapped allochthonous strata along the orogen side of the local Taconic foreland basin. Platform development followed a 6–8 my hiatus during which weathering had concentrated chemically mature siliciclastics that were admixed with initial carbonate sediments. A cross-platform facies gradient contains paleokarst and peritidal carbonates and sandstones, shallow-ramp carbonate bioherms and skeletal shoals, and deeper ramp calcareous shales. Transgressive systems tracts are marked by ramp-wide sheets and shoals of skeletal grainstone and low accumulation rates, and highstand systems tracts are marked by significant admixture and interbedding of siliciclastics with cross-ramp carbonate facies. Platform demise coincides with increased siliciclastic input, which is likely tectonically influenced. The Lourdes platform is equivalent to epicontinental foreland ramps along eastern Laurentia, but its narrower width precluded formation of oceanographically restricted platform-interior facies.     

High-resolution sequence stratigraphy of a mixed carbonate-siliciclastic, cratonic ramp (Upper Ordovician; Kentucky–Ohio, USA): insights into the relative influence of eustasy and tectonics through analysis of facies gradients

Detailed facies analysis and event stratigraphy of an Upper Ordovician (Rocklandian–Edenian) cratonic ramp succession in eastern North America yields insights into eustatically driven sequence architecture and localized tectonic instability. Seven, predominantly subtidal, mixed carbonate-siliciclastic depositional sequences (3rd order) are identified and correlated across the length of a 275-km ramp–to–basin profile. Within the larger depositional sequences (3rd order) at least two smaller orders (4th and 5th) of cyclicity are recognizable. Three systems tracts occur within each sequence (transgressive, TST; highstand, HST; regressive, RST) and are considered in terms of their component parasequences (5th order). Generally, TSTs are composed of skeletal grainstone–rudstone facies, HSTs are dominated by shaly nodular wacke-packstone facies, and RSTs are mostly calcarenite facies. Systems tracts, sequence boundaries and their correlative conformities, maximum flooding surfaces, and forced regression surfaces were traced from shallow shelf to basinal settings. This high-resolution framework also provides insight into the timing of tectonic fluctuations on this cratonic ramp during the Taconic Orogeny and documents the relative influence of tectonism on lateral facies distributions and eustatically derived cyclicity.     

Trilobite biofacies and sequence stratigraphy: an example from the Upper Ordovician of Oklahoma

There have been surprisingly few empirical investigations of the fundamental principle that the architecture of depositional sequences exerts considerable control on observed patterns of faunal distribution and replacement. In this paper, we examine trilobite associations in two sequences of the Upper Ordovician (Sandbian) Bromide Formation of southern Oklahoma. Cluster analysis and ordination of genus abundance data identified five lithofacies‐related biofacies that are also differentiated by diversity patterns. Biofacies of the transgressive system tract (TST) of successive sequences are more similar to each other than they are to biofacies in the highstand systems tract (HST) of the same sequence. This similarity likely records dominance of large, robust convex sclerites in taphonomically degraded samples from condensed, strongly winnowed grainstone and rudstone. Horizons with articulated exoskeletons of isoteline trilobites preserved by obrution deposits occur most commonly in the early HST and record behavioural aggregations. Grainstone and rudstone of the later HST are less winnowed than those of the TST and show less fragmentation and sorting of sclerites. These changes in taphonomic conditions preserve ecological patterns more clearly. In most biofacies, rarefied alpha diversity (samples) and gamma diversity (biofacies) of middle‐ and outer‐ramp HST deposits are greater than in the TSTs, and biofacies replace each other down ramp. Diversity patterns do not agree with model predictions and other data sets that indicate low beta and high alpha diversity in the TST, likely because of taphonomic degradation. Vertical replacement of biofacies is expressed by the appearance of peritidal facies in which trilobites are rare. Biofacies shifts also characterize sequence boundaries and are most profound in the inner‐ramp successions characterized by sharp facies offsets. Comparison with bathymetrically similar deposits in the Taconic foreland basin showed similar diversity trends along environmental gradients, with some differences in shallow‐water settings attributed to taphonomic differences.     

Facies of a Lower Ordovician carbonate shelf (Mungok Formation: Taebaeksan Basin,Korea)

Summary The lithologic associations within the Lower Ordovician Mungok Formation in Korea define four depositional facies that formed across a continental margin fringing the Sino-Korean block: these facies represent lagoonal/restricted marine, shoal, inner shelf, and outer shelf environments. The stacking pattern of these facies reveals two systems tracts composed of five depositional sequences. The lower highstand systems tract consists of the lagoonal/restricted marine and shoal facies, whereas the upper lowstand systems tract comprises, in ascending order, inner shelf, outer shelf, and inner shelf facies. Three trilobite biofacies are recognized in the Mungok Formation: i.e.,Yosimuraspis, Kainella, andShumardia biofacies in ascending order. TheYosimuraspis Biofacies is dominated byYosimuraspis but also containsJujuyaspis andElkanaspis. The predominance of the endemic eponymous taxon suggests a lagoonal/restricted marine environment. The nearly monotaxicKainella Biofacies, which comprises pandemic genera such asKainella and occasionallyLeiostegium, may represent a less restricted environment than theYosimuraspis Biofacies. TheShumardia Biofacies occurs in the marlstone/shale lithofacies through relatively thick stratigraphic interval and is dominated by cosmopolitan trilobite taxa with some endemic species. The lithofacies and cosmopolitan trilobite assemblage of theShumardia Biofacies indicate that it occupied an outer shelf environment. The vertical succession of lithofacies and trilobite biofacies in the Mungok Formation records in general a shift from a restricted, shallow water environment to deeper-water environment.     

Correlation of (Ordovician, Mohawkian) K-bentonites in the upper Mississippi valley using apatite chemistry: implications for stratigraphic interpretation of the mixed carbonate-siliciclastic Decorah Formation

Four Ordovician K-bentonites have been chemically fingerprinted using trace element content of apatite phenocrysts contained within the altered ash layers. Trace element analysis was performed using electron microprobe on individual crystals. The bentonites include the Deicke, Millbrig, Elkport, and Dickeyville beds. These beds lie within the Decorah Formation of the northern Mississippi Valley outcrop area. All four K-bentonite beds are believed to have a Taconic source whereas volcanic ash was transported by wind and deposited in the Ordovician North America epeiric sea.

The Decorah is a marine unit, shaly to the north and west and carbonate-rich to the south and east. Thirteen K-bentonite samples were collected from six localities. Only one locality (Dickeyville, WI) contains all four beds in succession. One hundred seventy-one apatite crystals were handpicked and analyzed for major, minor and trace elements using an electron microprobe. Each crystal was analyzed at three to six separate spots to ascertain compositional variation. The most discriminating and diagnostic elements were Mg and Mn; plotting Mg vs. Mn content produces data clusters characteristic for each K-bentonite. Clusters show only minimal change between localities, allowing individual K-bentonites to be identified and used for stratigraphic correlation.

Time slices provided by the K-bentonite horizons show that the Decorah Formation is composed of reciprocal wedges (stratigraphic sequences) of shale and carbonate. Shale was deposited in deeper water within the Hollandale Embayment but pinched out southeastward onto the flank of the Wisconsin Dome. Carbonates were formed largely in shoal water on the arch, prograding northwestward and shaling out downramp into the embayment.     

Facies analysis and sequence stratigraphy of an Upper Jurassic carbonate ramp in the Eastern Alborz range and Binalud Mountains, NE Iran

Upper Jurassic (Oxfordian-Kimmeridgian-Tithonian?) strata of NE Iran (Lar Formation) are composed of medium- to thick-bedded, mostly grainy limestones with various skeletal (bivalves, foraminifera, algae, corals, echinoderms, brachiopods, and radiolaria) and nonskeletal (peloids, ooids, intraclasts, and oncoids) components. Facies analysis documents low- to high-energy environments, including tidal-flat, lagoonal, barrier, and open-marine facies. Because of the wide lateral distribution of facies and the apparent absence of distinct paleobathymetric changes, the depositional system likely represents a westward-deepening homoclinal ramp. Four third-order depositional sequences can be distinguished in each of five stratigraphic measured sections. Transgressive system tracts (TST) show deepening-upward trends, in which shallow-water (tidal flat and lagoonal) facies are overlain by deeper-water (barrier and open-marine) facies. Highstand systems tracts (HST) show shallowing-upward trends in which deep-water facies are overlain by shallow-water facies. All sequence boundaries in the study area (except at the top of the stratigraphic column) are of the nonerosional (SB2) type. Correlation of depositional sequences in the studied sections show that relatively shallow marine (tidal-flat, lagoonal, barrier, and shallow open-marine) conditions dominated in the area. These alternated with deep-water open-marine wackestone and mudstones representing zones of maximum flooding (MFZ).     

Cenomanian rudist-dominated shelf-margin limestones from the panormide carbonate platform (Sicily, Italy): Facies analysis and sequence stratigraphy

Summary Sedimentological, paleontological and sequence analyses of Cenomanian limestones in Sicily reveal the facies architecture and dynamics of a Mid Cretaceous rudistdominated platform margin from Western Tethys. The studied deposits outcrop near Palermo, as part of a large structural unit of the Sicilian Maghrebids. They belong to the Panormide carbonate platform, a Mesocenozoic paleogeographic domain of the African margin. The lateral continuity of the beds along three nearly parallel E-W outcrop sections allowed the recording of cm/dm thick lithological and faunal variations. Nine main lithofacies associations have been recognised along about 200 m of subvertical strata. Their vertical and lateral organisation points to a transition from highenergy shelf-margin rudist patches and shoals to more internal lagoonal-tidal environments over a short distance. The lithofacies evolution and stacking pattern along the three sections made it possible to define elementary cycles, composite cycles and larger-scale sequences with a dominant shallowing-upward trend. Their hierarchical organisation implies that sea-level fluctuations were an important factor in their formation. The cycles are characterised by a great variation in facies as a result of transgressive-regressive events in different sectors of the inferred Cenomanian shelf. Subtidal cycles typical of the shelf margin (4–10 m-thick) are particularly well identifiable. They are made of large Caprinidae and Sauvagesiac rudstone-to-floatstone (about 2/3 of the total thickness), capped by rudist-conglomerates, often organised into 3–5 fining-upward amalgamated beds and showing, in places, effects of surface-related diagenesis. In more internal shelf areas the cycles consist of Caprinidae-Radiolitidae floastone grading up into amalgamated beds of angular bioclastic rudstone/grainstone. Alternations of foraminifer/ostracod mudstone/wackestone and bioclastic grainstone/fine-rudstone, capped by loferites and/or by other emersion-related overprintings, characterise the cycles formed in the peritidal zones. these cycles are stacked into three incomplete depositional sequences. The sequence boundaries have been identified by the abrupt interposition of peritidal cycles in subtidal rudist-rich cycles, with evidence of brief subaerial exposure.     

Facies architecture,depositional environments,and sequence stratigraphy of the Middle Cambrian Fasham and Deh-Sufiyan Formations in the central Alborz,Iran

Based on their lithologic characteristics and stratal geometries, the Middle Cambrian Fasham and Deh-Sufiyan Formations of the lower Mila Group in the Central Alborz, northern Iran, exhibit 39 lithofacies representing several supratidal to deep subtidal facies belts. The siliciclastic successions of the Fasham Formation are divided into two facies associations, suggesting deposition in a tide-dominated, open-mouthed estuarine setting. The mixed, predominantly carbonate successions of the Deh-Sufiyan Formation are grouped into ten facies associations. Four depositional zones are recognized on the Deh-Sufiyan ramp: basinal, outer ramp (deep subtidal associations), mid ramp (shallow subtidal to lower intertidal associations), and inner ramp (shoal and upper intertidal to supratidal associations). These facies associations are arranged in small-scale sedimentary cycles, i.e., peritidal, shallow subtidal, and deep subtidal cycles. These cycles reflect spatial differences in the reaction of the depositional system to small-scale relative sea-level changes. Small-scale cycles are stacked into medium-scale cycles that in turn are building blocks of large-scale cycles. Systematic changes in stacking pattern (cycle thickness, cycle type, and facies proportion) allow to reconstruct long-term changes in sea-level. Six large-scale cycles (S1–S6) have been identified and are interpreted as depositional sequences showing retrogradational (transgressive systems tract) and progradational (highstand systems tract) packages of facies associations. The six depositional sequences provide the basis for inter-regional sequence stratigraphic correlations and have been controlled by eustatic sea-level changes.     

Environmental change in the Early Permian of NE Svalbard: from a warm-water carbonate platform (Gipshuken Formation) to a temperate,mixed siliciclastic-carbonate ramp (Kapp Starostin Formation)

A detailed facies study of Early Permian strata within NE Svalbard reveals a fundamental change of the depositional setting, from a restricted-marine, warm-water carbonate platform to an open-marine, temperate-water, mixed siliciclastic-carbonate ramp. The uppermost strata of the Gipshuken Formation (Templet and Sørfonna members; Sakmarian–early Artinskian?) consist of microbialites (algal mats), mudstones, bioclastic/peloidal limestones, carbonate breccias and Microcodium facies reflecting peritidal platform areas and supratidal sabkhas. A mixed heterozoan/reduced photozoan assemblage indicates temperate-water conditions within neighboring deeper, open-marine mid-platform areas, while warm-water conditions still prevailed within inner platform zones. In contrast, the lowermost strata of the overlying Kapp Starostin Formation (Vøringen Member; late Artinskian?–Kungurian) show a fully heterozoan biotic assemblage reflecting temperate water conditions within open-marine, storm-dominated, nearshore to transitional offshore areas of a mixed carbonate-siliciclastic ramp. The Vøringen Member comprises three facies associations, which form a shallowing-upward sequence subsequent to an initial transgression. The sediments reflect bryozoan bioherms in most distal areas, followed by stacked tempestites of sandy brachiopodal shell banks and Skolithos piperocks, grading into broad sand flats in most proximal areas of the inner ramp. The above environmental change is regarded as a regional event taken place across the entire shelf along the northern margin of Pangea and is attributed to paleoclimatic, paleoceanographic, as well as paleogeographic changes, possibly related to the overall northwards drift of the supercontinent. An abrupt increase in terrigenous input coinciding with this change is ascribed to the uplift of a new local source area, probably to the north or east of the investigation area.     

Origin, sequence stratigraphy and depositional environment of an upper Ordovician (Hirnantian) deglacial black shale, Jordan

The upper Ordovician succession of Jordan was located 60°S, less than 100 km from the Hirnantian ice sheet margin. New graptolite dates indicate glaciation ended in Jordan in the late Hirnantian (persculptus Biozone). The succession records two glacial advances within the Ammar Formation and the subsequent deglaciations. Organic-rich black shales (Batra Formation) form part of the final deglacial transgressive succession that in-filled an existing low stand glacial continental shelf topography. The base of the black shale is coincident with the maximum flooding surface. During transgression, interfluves and sub-basin margins were breached and black shale deposition expanded rapidly across the region. The top of the black shales coincides with peak highstand. The “expanding puddle model” (sensu Wignall) for black shale deposition, adapted for the peri-glacial setting, provides the best explanation for this sequence of events.

We propose a hypothesis in which anoxic conditions were initiated beneath the halocline in a salinity stratified water column; a fresher surface layer resulted from ice meltwater generated during early deglaciation. During the initial stages of marine incursion, nutrients in the monimolimnion were isolated from the euphotic zone by the halocline. Increasing total organic carbon (TOC) and δ¹³C_org up section indicates the organic carbon content of the shales was controlled mainly by increasing bioproductivity in the mixolimnion (the Strakhov model). Mixolimnion nutrient levels were sustained by a continual and increasing supply of meltwater-derived nutrients, modulated by obliquity changes in high latitude insolation. Anoxia was sustained over tens to hundreds of thousands of years. The formation of black shales on the north Gondwana shelf was little different to those observed in modern black shale environments, suggesting that it was the nature of the Ordovician seas that pre-disposed them to anoxia.     

Facies models of a shallow-water carbonate ramp based on distribution of non-skeletal grains (Kimmeridgian,Spain)

The internal facies and sequence architecture of a Late Jurassic (Late Kimmeridgian) shallow carbonate ramp was reconstructed after the analysis and correlation of 17 logs located south of Teruel (northeast Spain). The studied rocks are arranged in five high-frequency sequences A–E (5–26 m thick) bounded by discontinuities traceable across the entire study area (20 × 25 km). Facies analysis across these sequences resulted in the reconstruction of three sedimentary models showing the transition from interior ramp environments (i.e., lagoon, backshoal, and shoal) to the progressively deeper foreshoal and offshore areas. Coral-microbial reefs (meter-sized patch and pinnacle reefs) have a variable development throughout the sequences, mostly in the foreshoal and offshore-proximal environments. The preferential occurrence and down-dip gradation of non-skeletal carbonate grains has been evaluated across the three models: low-energy peloidal-dominated, intermittent high-energy oolitic-dominated and high-energy oolitic–oncolitic dominated. The predominance of these non-skeletal grains in the shoal facies was mainly controlled by the hydrodynamic conditions and spatial heterogeneity of terrigenous input. The models illustrate particular cases of down-dip size-decrease of the resedimented grains (ooids, peloids, oncoids) due to storm-induced density flows. Offshore coarsening of certain particles (intraclasts, oncoids) is locally observed in the mid-ramp areas favorable for microbial activity, involving coral-microbial reef and oncoid development. The observed facies variations can be applicable to carbonate platforms including similar non-skeletal components, where outcrop conditions make the recognition of their three-dimensional distribution difficult.     

Paleoenvironmental model and sequence stratigraphy of the Asmari Formation in southwest Iran

The Asmari Formation is a thick carbonate succession of the Oligo-Miocene in southwest Iran (Zagros Basin). The Zagros Basin was a continental margin attached to the eastern edge of Africa throughout the Phanerozoic. The foraminiferal limestone from the Asmari Formation has been studied to determine its microfacies, paleoenvironments and sedimentary sequences. Based on analysis of larger benthic foraminiferal assemblages and microfacies features three major depositional environments are identified. These include open marine, barrier and lagoon-lower intertidal. These three are represented by eleven microfacies. A carbonate ramp platform is suggested for the depositional environment of the Asmari Formation. The inner ramp facies are characterized by wackestone-packstone, dominated by various taxa of imperforate foraminifera. The middle ramp facies represented by packstone-grainstone to floatstone with a diverse assemblage of larger hyaline foraminifera. The outer ramp is dominated by argillaceous wackestone, characterized by planktonic foraminifera and larger hyaline foraminifera. Two third-order sequences are identified based on deepening and shallowing patterns in microfacies, staking patterns and the distribution of Oligocene-Miocene foraminifers.     

Depositional environment and sequence stratigraphy of the Oligo-Miocene Asmari Formation in SW Iran

The Asmari Formation, a thick carbonate succession of the Oligo-Miocene in Zagros Mountains (southwest Iran), has been studied to determine its microfacies, paleoenvironments and sedimentary sequences. Detailed petrographic analysis of the deposits led to the recognition of 10 microfacies types. In addition, five major depositional environments were identified in the Asmari Formation. These include tidal flat, shelf lagoon, shoal, slope and basin environmental settings and are interpreted as a carbonate platform developed in an open shelf situation but without effective barriers separating the platform from the open ocean. The Asmari carbonate succession consists of four, thick shallowing-upward sequences (third-order cycles). No major hiatuses were recognized between these cycles. Therefore, the contacts are interpreted as SB2 sequence boundary types. The Pabdeh Formation, the deeper marine facies equivalent of the Asmari Limestone is interpreted to be deposited in an outer slope-basin environment. The microfacies of the Pabdeh Formation shows similarities to the Asmari Formation.     

Nobloedischia rasnitsyni, a new genus and species of Oedischiidae (Orthoptera) from the Lower Permian Wellington Formation of Oklahoma, USA

Nobloedischia rasnitsynigen. et sp. n. (Oedischiidae) is described from the Lower Permian Wellington Formation of Noble County, Oklahoma. The genus is similar to both Petrelcana (Oedischiidae: Mezenoedischiinae) and Oedischia (Oedischiidae: Oedischiinae) and is left unplaced at the subfamily level. The new species is the twelfth Orthoptera species and the fourth species of Oedischiidae from these deposits.     

Facies mosaic in the inner areas of a shallow carbonate ramp (Upper Jurassic,Higueruelas Fm,NE Spain)

The internal facies and sedimentary architecture of an Upper Jurassic inner carbonate ramp were reconstructed after the analysis and correlation of 14 logs in a 1 × 2 km outcrop area around the Mezalocha locality (south of Zaragoza, NE Spain). The studied interval is 10–16 m thick and belongs to the upper part of the uppermost Kimmeridgian–lower Tithonian Higueruelas Fm. On the basis of texture and relative proportion of the main skeletal and non-skeletal components, 6 facies and 12 subfacies were differentiated, which record subtidal (backshoal/washover, sheltered lagoon and pond/restricted lagoon) to intertidal subenvironments. The backshoal/washover subenvironment is characterized by peloidal wackestone–packstone and grainstone. The lagoon subenvironment includes oncolitic, stromatoporoid, and oncolitic-stromatoporoid (wackestone and packstone) facies. The intertidal subenvironment is represented by peloidal mudstone and packstone–grainstone with fenestral porosity. Gastropod-oncolitic (wackestone–packstone and grainstone) facies with intercalated marl may reflect local ponds in the intertidal or restricted lagoon subenvironments. Detailed facies mapping allowed us to document 7 sedimentary units within a general shallowing-upward trend, which reflect a mosaic distribution, especially for stromatoporoid and fenestral facies, with facies patches locally more than 500 m in lateral extent. External and internal factors controlled this heterogeneity, including resedimentation, topographic relief and substrate stability, combined with variations in sea-level. This mosaic facies distribution provides useful tools for more precise reconstructions of depositional heterogeneities, and this variability must be taken into account in order to obtain a solid sedimentary framework at the kilometer scale.     

Depositional facies and cyclic patterns in a subtidal-dominated ramp during the Early-Middle Ordovician in the western Tarim Basin (NW China)

Due to a long-term transgression since the Early Cambrian, an extensive shallow-water carbonate platform was developed in the entire Tarim Basin (NW China). During the deposition of the Yingshan Formation (Early-Middle Ordovician), a carbonate ramp system was formed in the intrashelf basin in the Bachu-Keping area of the western basin. Four well-exposed outcrop sections were selected to investigate their depositional facies, cycles, and sequences, as well as the depositional evolution. Detailed facies analyses permit the recognition of three depositional facies associations, including peritidal, semi-restricted subtidal, and open-marine subtidal facies, and eleven types of lithofacies. These are vertically arranged into meter-scale, shallowing-upward peritidal, semi-restricted subtidal, and open-marine subtidal cycles, in the span of Milankovitch frequency bands, suggesting a dominant control of Earth’s orbital forcing on the cyclic sedimentation on the platform. On the basis of vertical facies (or lithofacies) and cycle stacking patterns, as well as accommodation changes illustrated graphically by Fischer plots at all studied sections, six third-order depositional sequences are recognized and consist of lower transgressive and upper regressive parts. In shallow depositional settings, the transgressive packages are dominated by thicker-than-average, shallow subtidal cycles, whereas the regressive parts are mainly represented by thinner-than-average, relatively shallow subtidal to peritidal cycles. In relatively deep environments, however, the transgressive and regressive successions display the opposite trends of cycle stacking patterns, i.e., thinner-than-average subtidal cycles of transgressive packages. Sequence boundaries are mainly characterized by laterally traceable, transitional zones without apparent subaerial exposure features. Good correlation of the long-term changes in accommodation space inferred from vertical facies and cycle stacking patterns with sea-level fluctuations elsewhere around the world suggests an overriding eustatic control on cycle origination, platform building-up and evolution during the Early-Middle Ordovician, although with localized influences of syndepositional faulting and depositional settings.     

Hedyotis ouachitana (Rubiaceae): A new species from the Ouachita Mountains of Arkansas and Oklahoma

AHedyotis from the Ouachita Mountain region of Arkansas and Oklahoma is superficially similar toH. longifolia (Gaertn.) Hook., but differs consistently in pubescence of the inner corolla and pubescence of the lower stem. It occupies a different habitat and apparently does not hybridize withH. longifolia var.longifolia when the two occur in close proximity. It is described asH. ouachitana.     

Coral-microbialite reefs in pure carbonate versus mixed carbonate-siliciclastic depositional environments: the example of the Pagny-sur-Meuse section (Upper Jurassic,northeastern France)

Middle to Upper Oxfordian reefs of a shallow marine carbonate platform located in northeastern France show important facies changes in conjunction with terrigeneous contents. The Pagny-sur-Meuse section shows coral-microbialite reefs that developed both in pure carbonate limestones and in mixed carbonate-siliciclastic deposits. Phototrophic coral associations dominated in pure carbonate environments, whereas a mixed phototrophic/heterotrophic coral fauna occurred in more siliciclastic settings. Microbialites occur in pure carbonate facies but are more abundant in mixed carbonate-siliciclastic settings. Reefs seem to have lived through periods favourable for intense coral growth that was contemporaneous with a first microbialitic layer and periods more favourable for large microbialitic development (second microbialitic layer). The first microbialitic crust probably developed within the reef body and thus appears to be controlled by autogenic factors. The second generation of microbialites tended to develop over the entire reef surface and was probably mainly controlled by allogenic factors. Variations in terrigeneous input and nutrient content, rather related to climatic conditions than to water depth and accumulation rate, were major factors controlling development of reefs and their taxonomic composition.     

Facies arrangement and cyclostratigraphic architecture of a shallow-marine,warm-water carbonate platform: the Late Carboniferous Ny Friesland Platform in eastern Spitsbergen (Pyefjellet Beds,Wordiekammen Formation,Gipsdalen Group)

During the Late Carboniferous, a spacious warm-water carbonate platform developed across the eastern part of the present Arctic archipelago of Svalbard. The platform initiated in the Moscovian on an uplifted fault block (Ny Friesland High) and progradated during the Late Moscovian to Early Kasimovian into the adjacent Campbellryggen Basin (central Spitsbergen). The fossiliferous platform strata are characterized by a pronounced cyclicity formed by stacked parasequences, which consist of defined, subtidal to supratidal facies-set successions reflecting a general shallowing of the depositional area. Up to 17 of these shallowing-upward cycles, bounded by distinct discontinuity (marine flooding) surfaces due to the recurrent emersion and subsequent flooding of the platform surface, have been recognized within the platform strata. The stacked cycles are the result of global, glacio-eustatic, high-frequent and high-amplitudinal sea-level fluctuations with eccentricity periodicities caused by ice volume changes during the Gondwana Land glaciation. Based on systematic changes of the cycles (thickness and internal facies composition), the upper part of the platform strata is interpreted as a progradational parasequence set of a late highstand system tract. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.