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

Sedimentology Working Group 2025 Workshop with International Participants, İzmir, Turkey, 11 - 14 September 2025, pp.49-50, (Summary Text)

Upper Jurassic-Lower Cretaceous marine microbial carbonates are recorded on two different carbonate

platforms, 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 siliciclastic

material.

Marine microbial carbonates can be observed as laminar stromatolite facies and display alternation with

intertidal birdseye/fenestral limestones in Tauride Platform. The laminar stromatolites can be covered by

subaerial exposure features such as mudcrack, dissolution vug and microkarstic mantling breccia, or

microboring. Laminae of the stromatolites is composed of alternation of pelloidal lamina and phylloid

micritic lamina. In some localities, wavy laminates are observed too. The color of the stromatolites are

generally 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 staining

within 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 of

grains/laminae. Pinkish-reddish stromatolites display alternation with pelloidal grainstone/packstone,

intraclastic grainstone/packstone or oncoidal wackestone/grainstone facies with partly iron

encrusted/corroded surfaces around pelloids, oncoids and intraclasts on Pontide Carbonate Platform.

Stromatolites on the Tauride platform display a considerable increase in occurrence and in thickness

ranging between 1 to 2.5 meters in Aptian. However, the stromatolite thickness is relatively thinner in

Pontides and take place in the Berriasian. The Berriasian stromatolites in Taurides are thin and less

frequent. Color of the stromatolites in Taurides are changing from cream to dark gray/black. Dark

gray/black colored stromatolites may coincide with possible oceanographic/climatic events in Late

Jurassic and Early Cretaceous in Taurides.

Stromatolites generally took place on relatively early sea level rise and high stand conditions on the

Tauride carbonate platform, and they decrease in frequency just before the drowning of the Pontide

platform.

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 caps

and cover almost quarter of the Tauride carbonate platform evolution.

Consequently, sea-level variations with high frequency, possible storms and

paleoclimatic/paleoceanographic conditions were controlling factors on studied shallow water carbonate

platforms. Responses of microbial organisms to these conditions were different on both platforms and

produced different colored and composition of the microbial laminates and covered the important fraction

in the evolution of carbonate platforms.