Automicrite facies on steep slopes (Triassic, Dolomites, Italy)

Keim, Lorenz; Schlager, Wolfgang

doi:10.1007/bf02537457

Cited by 70 publications

(40 citation statements)

References 19 publications

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“…1). The wavy micrite layers, intercalated by fibrous cement, mimic a distinct growth structure probably determined by organic mats (Keim and Schlager 1999 Fig. 5, 6).…”

Section: Facies Typesmentioning

confidence: 96%

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An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis

Popa¹,

Panaiotu²,

Grădinaru³

2014

Acta Geologica Polonica

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ABSTRACT:Popa, L., Panaiotu, C.E. and Grădinaru, E. 2014. An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis. Acta Geologica Polonica, 64 (2), 189-206. Warszawa.A well-developed Triassic carbonate platform is exposed in the eastern part of the Tulcea Unit, in the Cimmerian North Dobrogean Orogen, southeastern Romania. Facies analysis of the 200 m thick succession of lower Middle Anisian limestones exposed in a large limestone quarry south of the village of Mahmudia suggests a transition from upper slope towards toe-of-slope carbonate facies, reflecting sea-level fluctuations and tectonic tilting. The slope is dominated by in situ microbialites in the upper portion, consisting of reefal boundstone facies, and by molluscan coquina and cement boundstones. A key role is played by the cosmopolitan micro-encruster Tubiphytes, which became common in the aftermath of the mass extinction at the Permian/Triassic boundary, and by autochthonous micrite and synsedimentary marine cement. The absence of metazoan reef builders, such as sponges and corals, reflects the fact that microbes were the first organisms to recover after the Permian/Triassic crisis under unusual marine conditions and that their main role in reef formation was sediment stabilization along the upper slopes. The lower slope is mostly detrital, being dominated by platform-derived bioclastic rudstones and crinoidal floatstones, which are interbedded with basinal carbonate hemipelagics. The toe-of-slope is composed of pelagic wackestones framed by thin tongues of intraclast breccia. All these observations are in agreement with the slopeshedding model described for the Pennsylvanian microbial margin in Asturias (northern Spain) and the AnisianLadinian flat-topped, steep-rimmed Latemar platform (Dolomites, Italy).As most of the Anisian reefs were described from western and eastern Tethys (Southern Alps, Hungary, China), the occurrence of the early Middle Anisian Tubiphytes-reef from North Dobrogea (Romania) contributes to resolving the puzzle of the geographic distribution of reef recovery in the Middle Triassic.

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“…1). The wavy micrite layers, intercalated by fibrous cement, mimic a distinct growth structure probably determined by organic mats (Keim and Schlager 1999 Fig. 5, 6).…”

Section: Facies Typesmentioning

confidence: 96%

“…Generally, automicrite formation ranged from the outer part of the platform downslope to over 200 m depth (Keim and Schlager 1999;Della Porta et al 2004).…”

Section: Depositional Environmentmentioning

confidence: 99%

An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis

Popa¹,

Panaiotu²,

Grădinaru³

2014

Acta Geologica Polonica

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“…Reitner and Neuweiler, 1995;Keim and Schlager, 1999). Several authors described limestone having clotted micrite microfacies as typical deposits of platform margins and slopes (Blendinger, 1994; Keim ______________________________________ ____________________ ___________________ 7.…”

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confidence: 99%

Microfacies associations of Middle and Upper Triassic slope and basin carbonates deposited along the Neo-Tethyan margin, NE Hungary

Horváth¹,

Hips²

2015

AJES

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Microfacies types presented here are based on thin section analysis of more than 1.500 samples from drilling cores, surface sections and several outcrops from Middle and Upper Triassic slope and basin carbonates in the Aggtelek-Rudabánya Hills (Hungary).The observed compositional and textural types were grouped into five microfacies associations which are characteristic for slope and basin environments. The clotted micrite "boundstone" typically contains bioclasts, peloids and stromatactis structures. The inhomogeneous clotted micrite-rich groundmass suggests that the sediment originated from mats or mounds enriched in organic matter. Bioclastic wackestone with radiolarians, pelagic bivalve shells and signs of bioturbation was likely deposited in deep-water basinal environment. Bioclastic grainstone-packstone and bivalve-crinoid packstone deposited from turbidity currents which often occurred along the slope. The mudstones can be found after events of sudden deepening, mostly related to the drowning of the Steinalm platform. Data based on comparison of stratigraphical logs show that the Middle Triassic was characterised by rapid deepening followed by the formation and expansion of a carbonate slope. During the Late Triassic, the breakup of the Wetterstein platform had an effect on slope environment as well.Die hier präsentierten Mikrofazies-Typen basieren auf der Analyse von mehr als 1500 Proben der Region Aggtelek-Rudabanya

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“…The carbonate factory of the Esino Limestone is thus partly different from that of other high-relief Carboniferous (e.g. Della Porta et al, 2003;2004;Kenter et al, 2005) or Triassic (Keim & Schlager, 1999;Marangon et al, 2011) carbonate platforms. In these platforms, microbial production characterizes also the slope below the photic zone, up to more than 300 m of water depth.…”

Section: Geological Settingmentioning

confidence: 90%

“…Sierra de Cuera; Della Porta et al, 2002;2004) or for age (e.g. carbonate platforms of the Dolomites; Keim & Schlager, 1999;Marangon et al, 2011). To simulate the greater production at depth of the microbial-rich reefs, compared to present day coral reefs, we set the depth for maximum reef production at 8 m (Tab.…”

Section: Sediment Productionmentioning

confidence: 99%

Forward modelling of carbonate platforms: Sedimentological and diagenetic constraints from an application to a flat-topped greenhouse platform (Triassic, Southern Alps, Italy)

Berra

Lanfranchi

Smart³

et al. 2016

Marine and Petroleum Geology

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•We propose a quantitative analysis of a carbonate platform using 3d numerical models.• Parameter definition is critical to produce realistic 3d numerical models.• Modelling parameters were defined by architectural and sedimentological studies. •The obtained model has been tested by comparison with outcrop and laboratory data.• 3d numerical models may help to parameterise petrophysical properties of geobodies.Key words: carbonate platform, forward modelling, Triassic, facies analysis, diagenesis 2 AbstractQuantitative analysis of depositional systems using numerical models can provide insights into the interaction of sedimentological and diagenetic processes, difficult to interpret from observation of the geological products alone. Numerical models can highlight the interactions between controlling parameters, and generate best estimate simulations of case studies from the geological record. Different data sources (e.g., outcrop data, uniformitarian constraints, paleogeography) need to be considered in the process of defining the parameters required to produce models that honour individual case studies. We present a best-estimate forward model of a high-relief Triassic carbonate platform (Southern Alps, Italy) generated using CARB3D+, a 3D process-based forward modelling package able to simulate sedimentary facies, geometries and early diagenesis of isolated carbonate platforms. The parameters used for the presented forward model have been deduced by the study of architectural, sedimentological and diagenetic features of the platform, and by data from modern and ancient analogues. Sensitivity analysis is used to tune values of the parameters within ranges defined from field, laboratory and uniformitarian constraints. Critical evaluation of the model allowed 1) verification of the validity of the used parameters; 2) evaluation of the interaction between controlling parameters; 3) development of a numerical model that can be used for quantitative elaborations. Furthermore, the process of generating the numerical model required a detailed interpretation of field and laboratory data, crucial to define the required input parameters. Modelling the studied carbonate platform also enabled evaluation of the effects of the interaction between productivity, environmental energy and creation of accommodation space, promoting the understanding of their role on the architecture of carbonate systems. Forward modelling also allows the integration of data from conventional data sets with data from presentday observations and seismic geometries, promoting a transition from a qualitative to a semiquantitative/quantitative sedimentological approach. Forward models can further be used to parameterise petrophysical properties of complex geobodies, with potential application for the management of georesources.

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Automicrite facies on steep slopes (Triassic, Dolomites, Italy)

Cited by 70 publications

References 19 publications

An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis

An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis

Microfacies associations of Middle and Upper Triassic slope and basin carbonates deposited along the Neo-Tethyan margin, NE Hungary

Forward modelling of carbonate platforms: Sedimentological and diagenetic constraints from an application to a flat-topped greenhouse platform (Triassic, Southern Alps, Italy)

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