IMPORTANCE OF MARINE MICROBIALITES IN UPPER JURASSIC-LOWER CRETACEOUS SUCCESSIONS OF CENTRAL TAURIDE AND WESTERNPONTIDE CARBONATE PLATFORMS

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2025-09-11

Author

Yılmaz, İsmail Ömer

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Upper Jurassic-Lower Cretaceous marine microbial carbonates are recorded on two different carbonateplatforms, the Tauride and the Pontide platforms in the south- and north-western , respectively.They occur within the cyclic peritidal carbonates on both platforms and do not contain any siliciclasticmaterial.Marine microbial carbonates can be observed as laminar stromatolite facies and display alternation withintertidal birdseye/fenestral limestones in Tauride Platform. The laminar stromatolites can be covered bysubaerial exposure features such as mudcrack, dissolution vug and microkarstic mantling breccia, ormicroboring. Laminae of the stromatolites is composed of alternation of pelloidal lamina and phylloidmicritic lamina. In some localities, wavy laminates are observed too. The color of the stromatolites aregenerally beige-white and dark gray color is also observed in some localities.Microbial laminates display reddish-pinkish colored laminar and wavy features and include iron stainingwithin the pelloidal laminae. This iron encrustation is not well observed within matrix or cements.Therefore, it can be interpreted as meteorological contribution during transportation/deposition ofgrains/laminae. Pinkish-reddish stromatolites display alternation with pelloidal grainstone/packstone,intraclastic grainstone/packstone or oncoidal wackestone/grainstone facies with partly ironencrusted/corroded surfaces around pelloids, oncoids and intraclasts on Pontide Carbonate Platform.Stromatolites on the Tauride platform display a considerable increase in occurrence and in thicknessranging between 1 to 2.5 meters in Aptian. However, the stromatolite thickness is relatively thinner inPontides and take place in the Berriasian. The Berriasian stromatolites in Taurides are thin and lessfrequent. Color of the stromatolites in Taurides are changing from cream to dark gray/black. Darkgray/black colored stromatolites may coincide with possible oceanographic/climatic events in LateJurassic and Early Cretaceous in Taurides.Stromatolites generally took place on relatively early sea level rise and high stand conditions on theTauride carbonate platform, and they decrease in frequency just before the drowning of the Pontideplatform.Cyclic facies alternations of stromatolites display shallowing upward character and alternate with subtidal,intertidal and supratidal carbonates. In some microbial carbonates lie on the top of the cycles as cycle capsand cover almost quarter of the Tauride carbonate platform evolution.Consequently, sea-level variations with high frequency, possible storms andpaleoclimatic/paleoceanographic conditions were controlling factors on studied shallow water carbonateplatforms. Responses of microbial organisms to these conditions were different on both platforms andproduced different colored and composition of the microbial laminates and covered the important fractionin the evolution of carbonate platforms.

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https://hdl.handle.net/11511/119510

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Department of Geological Engineering, Conference / Seminar