Response of triassic reef coral communities to sea-level fluctuations, storms and sedimentation: Evidence from a spectacular outcrop (Adnet, Austria)

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.

Section: Methodsmentioning

confidence: 99%

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

Olivier

Carpentier

Martin-Garin

et al. 2004

“…The overall sedimentology and biostratigraphy of Triassic deposits are well established in the western Tethyan realm and various studies including those dealing with paleogeography and geodynamic models are known: Italy and Sicily (Miconnet et al 1983;Zaninetti et al 1984;Senowbari-Daryan et al 1985;Carcione et al 2003), Greece (Schäfer and Senowbari-Daryan 1982), Austria (Hohenegger and Piller 1975;Enos and Samankassou 1998;Bernecker et al 1999), Slovakian and Polish Carpathians (Michalik 1982;Gazdzicki 1983), Oman (Bernecker 1996(Bernecker , 2005Weidlich et al 1993;SenowbariDaryan et al 1999), Arab Emirates Senowbari-Daryan and Maurer 2008), Indonesia (Al-Shaibani et al 1983;Villeneuve et al 1994;Martini et al 1997Martini et al , 2004, Philippines (Kiessling and Flügel 2000) and Australia (Kristan-Tollmann and Gramann 1992;Zaninetti et al 1992). Triassic reefs are particularly well studied (e.g., Kanmera 1964;Flügel 1981;SenowbariDaryan 1981, 1982;Flügel 1982Flügel , 2002Flügel and Stanley 1984;Stanley and Gonzalez-Leon 1997;SenowbariDaryan et al 1999;Bernecker et al 1999;Kiessling et al 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Triassic reefs are particularly well studied (e.g., Kanmera 1964;Flügel 1981;SenowbariDaryan 1981, 1982;Flügel 1982Flügel , 2002Flügel and Stanley 1984;Stanley and Gonzalez-Leon 1997;SenowbariDaryan et al 1999;Bernecker et al 1999;Kiessling et al 1999). By contrast, Triassic sequences that were originated in the Panthalassan Ocean are poorly documented.…”

Section: Introductionmentioning

confidence: 99%

Microfacies and depositional setting of the Upper Triassic mid-oceanic atoll-type carbonates of the Sambosan Accretionary Complex (southern Kyushu, Japan)

Chablais

Martini

Samankassou

et al. 2009

The Upper Triassic shallow-water limestones of the Sambosan Accretionary Complex are reconstructed as a remnant of a mid-oceanic atoll-type build-up upon a seamount in the Panthalassan Ocean. The Sambosan atolltype carbonates and its pedestal were accreted along with deep-water ribbon-chert and related siliceous rocks to the eastern margin of Asia during the Late Jurassic to Early Cretaceous. Studied limestones crop out in southern Kyushu Island, southwest Japan. Although the prevailing and intense deformation during the accretionary process prevents measurement of sections in stratigraphic successions, and sedimentary structures are poorly preserved, microfacies description and foraminifers analysis allow us to speculate the depositional setting of the Sambosan limestones. Seventeen microfacies are distinguished and several foraminifers of Tethyan affinity are identified. Foraminifers indicate a Late Carnian to Rhaetian age. The Tethyan affinity of the macro-and microfaunas suggests that the Sambosan seamount was located presumably in a low-to middle-latitudinal zone of the southern hemisphere during the Late Triassic.

“…This can be a consequence of several factors related to the dominance of destructive taphonomic processes (high rate of degradation due to bioerosion and storm activity, e.g. Kuss 1983;Bernecker et al 1999), perhaps the ecology of frame-building organisms (according to Stanton and Flügel 1987, branching retiophyllid corals mostly did not build rigid wave-resistant framework that could withstand the highest wave activity, but there are contradictory opinions, see Piller 1981;Schäfer 1984;Schäfer and Senowbari-Daryan 1981), environmental restriction/instability of Fatric intra-shelf setting leading to poor species richness (Michalík 1982), and/or slow subsidence or slow eustatic sea level rise (limited accommodation space). A comparable depositional model was developed for the lower part of the Kössen Formation (Kuss 1983).…”

Section: Depositional Environmentmentioning

confidence: 99%

Microfacies and depositional environment of an Upper Triassic intra-platform carbonate basin: the Fatric Unit of the West Carpathians (Slovakia)

Tomášových

2004

Facies associations of the Rhaetian Fatra Formation from the Veľkµ Fatra Mts. (West Carpathians) were deposited in a storm-dominated, shallow, intraplatform basin with dominant carbonate deposition and variable onshore peritidal and subtidal deposits, with 21 microfacies types supported by a cluster analysis. The deposits are formed by bivalves, gastropods, brachiopods, echinoderms, corals, foraminifers and red algae, ooids, intraclasts and peloids. A typical feature is the considerable variation in horizontal direction. The relative abundance and state of preservation of components as well as the fabric and geometric criteria of deposits can be correlated with depth/water energy-related environmental gradients. Four facies associations corresponding to four types of depositional settings were distinguished: a) peritidal, b) shoreface, above fair-weather wave base (FWWB), c) shallow subtidal, above normal storm wave base and d) above maximum storm wave base. The depositional environment can be characterized as a mosaic of low-relief peritidal flats and islands, shoreface banks and bars, and shallow subtidal depressions. The distribution and preservation of components were mainly controlled by the position of base level (FWWB), storm activity and differences in carbonate production between settings. Poorly or moderately diverse level-bottom macrobenthic assemblages are dominated by molluscs and brachiopods. The main site of patch-reef/biostrome carbonate production was located below the fair-weather wave base. Patch-reef/biostrome assemblages are poorly diverse and dominated by the branched scleractinian coral Retiophyllia, forming locally dm-scale autochthonous aggregations or more commonly parautochthonous assemblages with evidence of storm-reworking and substantial bioerosion by microborings and boring bivalves.Facies types and assemblages are comparable in some aspects to those known from the Upper Triassic of the Eastern and Southern Alps (Hochalm member of the Kössen Formation or Calcare di Zu Formation), pointing to similar intra-platform depositional conditions. The absence of large-scale patch-reefs and poor diversity of level-bottom and patch-reef/biostrome assemblages with abundance of eurytopic taxa indicate high-stress/unstable ecological conditions and more restricted position of the Fatric intra-platform setting from the open ocean than the intra-platform habitats in the Eastern or Southern Alps.