UPPER JURASSIC – LOWER CRETACEOUS CARBONATE PLATFORM MARGIN SUCCESSIONS OF THE EASTERN PONTIDES: CORRELATION OF THE PLATFORM AND BASIN, IMPLICATIONS FOR THE J/K BOUNDARY

Date

2024-8

Author

Atasoy, Serdar Görkem

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The Upper Jurassic – Lower Cretaceous chronostratigraphic interval is characterized by unstandardized stages and includes the only Phanerozoic system boundary without a Global Boundary Stratotype Section and Point – the Jurassic/Cretaceous (J/K) boundary. Recent research has been mainly focused on deep marine continuous successions from the Tethyan region and provided important progress in calibration of pelagic bioevents. However, the correlation of these pelagic zonations with the schemes from shallow marine deposits is still obscure. Biostratigraphical data from marginal carbonates containing fossils both from the platform and basinal facies can provide the required links between these two distinct depositional environments. This kind of Upper Jurassic – Lower Cretaceous carbonates crop out in the Eastern Pontides in close association with the coeval shallow and deep marine successions. Four stratigraphical sections were measured and logged in detail along the neritic and pelagic carbonates. Four biozones and two subzones were defined in the shallow marine successions by using benthic foraminifera and microencrusters that ranges the Kimmeridgian – Hauterivian interval. Six biozones and nine subzones were differentiated in the slope to basin successions for the Kimmeridgian – Valanginian interval, based on calpionellids, benthic foraminifera, microencrusters and pelagic crinoids. These successions were calibrated with a composite standard reference section through the application of the Graphic Correlation and Unitary Associations methods to overcome facies controlled biohorizons and calibrate fossil datums from unrelated phylogenies. Calibration of the Pontides Composite Reference Section with the Geological Time Scale (2020) reveals relative positions of both shallow and deep marine bioevents with respect to the Oxfordian – Hauterivian stage boundaries. A depositional model with biofacies belts was produced for the Upper Jurassic – Lower Cretaceous successions of the Eastern Pontides.

Subject Keywords

Upper Jurassic-Lower Cretaceous Carbonate Platforms, Calpionellid and Foraminifera Biostratigraphy, Eastern Pontides, Jurassic-Cretaceous Boundary, Quantitative Biostratigraphy

URI

https://hdl.handle.net/11511/111571

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Graduate School of Natural and Applied Sciences, Thesis