AI Summary & Key Takeaways
AI InsightThe Oligocene transgression culminated in the area with the deposition of platform-type carbonatesand it continued during the early Miocene.
📌 3 Key Takeaways
Abstract
The Sivas Cenozoic Basin and coeval Central Anatolian basins such as Çankırı and Tuz Gölü are characterized by both marineand terrestrial sediments ranging in age from the Eocene to early Miocene. The evaporite regime here generally appeared during the latestage of Eocene transgression and persisted through the Oligocene time. However, marine-induced Oligocene evaporites are less knownbecause of less paleontological evidence and regional tectonics and salt diapirism that mostly caused the destruction of their originalstratigraphic positions. The Eğribucak area studied here, located about 25 km southeast of Sivas ,provides a well-stratified key sectionto shed light on the depositional history of the Oligocene marine evaporite (coastal lagoon or sabkha complex) and other associatedcarbonate and siliciclastic units. The Eğribucak succession has a thickness of approximately 400 m and rests on thick fluviatile sedimentscommencing with red beds (mudstone, sandstone, and gravelly sandstone), and upwards, terrestrial gypsums are present within the redunits as thin beds that are overlain by thick marine gypsum beds with rhythmical alternations of gray and green colored sandstone- marly limestone and limestone. The limestones alternating with the thick gypsum beds are rich in benthic foraminifers yielding aRupelian-Chattian age. At the top of the section evaporites disappeared and lagoon-type limestone turned into thick platform carbonatedated as Oligocene-early Miocene. The Eğribucak succession shows a wide variety of depositional environments ranging from terrestrialto restricted marine to open marine from bottom to top. The short periods of the lithological alternations from siliciclastic to carbonateand evaporite indicate that the evaporite environment was not consistent through the Oligocene period. This would be formed as amarginal evaporite environment, presumably a coastal lagoon/sabkha affected by seasonal variations with arid and humid periods aswell as eustatic sea-level changes. The Oligocene transgression culminated in the area with the deposition of platform-type carbonatesand it continued during the early Miocene.