Carbonate facies dominated by syndepositional cements: a key component of Middle Triassic platforms. The Marmolada case history (Dolomites, Italy)

Russo, Federico; Mastandrea, Adelaide; Stefani, Marco; Neri, Camillo

doi:10.1007/bf02562573

Cited by 50 publications

(46 citation statements)

References 26 publications

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“…They may have been microbially mediated to some degree because some layers of isopachous fibrous cements are overgrown by darkcolored microbial laminae. Such concentric crusts consisting of radiaxial fibrous marine cements are well developed at the outer margin and on the proximal slope of Triassic carbonate platforms in Italy (Russo et al 2000). This is consistent with the suggested proximal fore-reef slope setting for Mengcun mound.…”

Section: Discussionsupporting

confidence: 55%

Mississippian (Early Carboniferous) stromatolite mounds in a fore-reef slope setting, Laibin, Guangxi, South China

Shen

Qing

2008

Int J Earth Sci (Geol Rundsch)

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The Mississippian (Early Carboniferous) is generally a period of scarce carbonate buildups in South China. This study documents outcrops of stromatolite mounds at Mengcun and Helv villages, in Laibin City, Guangxi Province, South China. The stromatolite mounds contain various stromatolite morphologies including laminar, wavy-laminar, domal or hemispheroidal, bulbous, and flabellate-growth columns. Intramound rocks are brachiopod floatstone and dark thin-bedded laminated micrite limestone. Individual stromatolites at Mengcun village are generally 3-6 cm thick and morphologically represent relatively shallow-water laminar (planar and wavy-undulated stromatolites) and deeper-water domal, bulbous and columnar forms. Where mounds were formed, the stromatolites continued growing upward up to 60 cm thick. Thrombolitic fabrics also occur but are not common. Stromatolite microscopic structure shows the bulk of the lamination to consist of wavy microbialite and discrete thin micritic laminae. These mounds are intercalated in deep-water fore-reef talus breccia, packstone formed as a bioclastic debris flow and thin-bedded limestone containing common chert layers of the Tatang Formation (late Viséan). Further evidence supporting the deep-water setting of the stromatolite mounds are: (1) a laterally thinning horizon of brachiopod floatstone containing deepwater, small, thin-shelled brachiopods, peloidal micritic sediments and low-diversity, mixed fauna (e.g., thin-shelled brachiopods, tube-like worms and algae) that have been interpreted as storm deposits, (2) common fore-reef talus breccias, (3) lack of sedimentary structures indicating current action, (4) preservation of lamination with sponge spicules, and (5) lack of bioturbation suggesting that the stromatolites grew in a relatively low energy, deep-water setting. The stromatolite mounds are the first described stromatolite mounds in Mississippian strata of South China and contain evidence that supports interpretations of (1) growth history of Mississippian microbial buildups and (2) environmental controls on stromatolite growth and lithification.

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Section: Discussionsupporting

confidence: 55%

Mississippian (Early Carboniferous) stromatolite mounds in a fore-reef slope setting, Laibin, Guangxi, South China

Shen

Qing

2008

Int J Earth Sci (Geol Rundsch)

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“…From this point of view, the lower Middle Anisian section in the Mahmudia Quarry resembles the shelf-edge framestones of the Anisian Chinese reefs (Enos et al 1997(Enos et al , 2006Payne et al 2006) and the Middle Anisian to Lower Ladinian boundstone facies of Latemar (Harris 1993;Emmerich et al 2005;Marangon et al 2011) and Marmolada (Russo et al 2000), both in the Italian Dolomites, and the Middle Anisian carbonate mounds in central Iran (Berra et al 2012).…”

Section: Comparison With Other Tubiphytes-buildups Known In the Geolomentioning

confidence: 96%

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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“…This attribution is based on the numerous papers that describe the facies of the Middle Triassic platforms of the region (e.g. Bosellini and Rossi 1974;Gaetani et al 1981;Fois 1982;Harris 1993Harris , 1994Egenhoff et al 1999;Russo et al 2000).…”

Section: Volume Of Turbidites In Corementioning

confidence: 99%

“…Point-count group 9 (non-identifiable carbonate grains) notwithstanding, structural skeletal grains (group 3) have the lowest occurrence with 1.5 (0.75%). The mean values reflect the overall composition of the carbonate platform source sediment, which is characterized by an abundance in peloidal bound-and grainstones and a low percentage of skeletal grains (Russo et al 2000).…”

Section: Summary Statistics Of Compositionmentioning

confidence: 99%

Quantification of input and compositional variations of calciturbidites in a Middle Triassic basinal succession (Seceda, Dolomites, Southern Alps)

Maurer¹,

Reijmer

Schlager³

2003

International Journal of Earth Sciences

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Triassic calciturbidites were studied in a 100-m long core and nearby outcrops of the basinal Buchenstein Formation to determine composition and thickness variations. The quantity of recognized turbidite sediment relative to background sediment changes from 15% (by volume) in the lower part to 60% in the upper part, reflecting the steady progradation of nearby platforms. The composition of the sand fraction of 214 turbidites was point-counted in thin sections. Micrite peloids (average 23%) and lithoclasts (16%) are by far the most dominant constituents. They are interpreted as two different varieties of in-situ precipitated micrite (automicrite), which probably formed under the influence of microbes and constitute the principal building material of the adjacent platforms. Platform-derived skeletal grains amount to only 0.5%. Variations in turbidite composition were quantified using Spearman's rank correlation and cluster analysis. The most significant compositional variations seem to be related to hydrodynamic sorting in the turbidity currents and to the gradual shift from distal to more proximal turbidites in the core as the platforms prograded basinward. Cluster analysis of the 214 samples shows a major subdivision into micrite and sparite dominated turbidites. Clusters associated with micritedominated turbidites are enriched in Radiolaria and thinshelled bivalves, whereas the clusters related to sparitedominated turbidites show an abundance of lithoclasts. This subdivision seems strongly related to sorting effects in a turbidity current. Point-counting of turbidites in nearby outcrops revealed a lateral variation in composition. Proximal turbidites are sparite-dominated and enriched in lithoclasts, distal portions are chiefly micrite with an open-ocean biota (thin-shelled bivalves, Radiolaria). This differentiation resembles the vertical change in composition of thick turbidite beds, and is attributed to different settling rates of the various grains in the turbidity current. There is no indication that turbidite composition fluctuated significantly under the influence of sea-level fluctuations. This is not surprising because the dominant automicrite facies of the platforms only migrates laterally, but does not change much during sealevel cycles.

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Carbonate facies dominated by syndepositional cements: a key component of Middle Triassic platforms. The Marmolada case history (Dolomites, Italy)

Cited by 50 publications

References 26 publications

Mississippian (Early Carboniferous) stromatolite mounds in a fore-reef slope setting, Laibin, Guangxi, South China

Mississippian (Early Carboniferous) stromatolite mounds in a fore-reef slope setting, Laibin, Guangxi, South China

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

Quantification of input and compositional variations of calciturbidites in a Middle Triassic basinal succession (Seceda, Dolomites, Southern Alps)

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