Section of the Paleocene- Eocene in the region of the Ak-Kaya Mountain (Central Crimea) and its geohistorical interpretation

Abstract

The results of a detailed study of outcrops of the eastern flank of Ak-Kaya Mountain are given. There are continuous outcrops (over a distance of 400 m) of Paleocene and Eocene sediments with a thickness of 12 m in the south-west to 24 m in the northeast, which lie unconformably on the Upper Cretaceous (Maastrichtian) limestones and are covered by Oligocene-Miocene Maikop clays. The detailed structural-substantial characteristic, sedimentary structures, tafonomic characteristics of the sections of the Belokamensk, Bakhchisaray and Simferopol regional stages, which were compiled from the results of field descriptions of outcrops, microscopic examination of thin sections and computed microtomography of samples, are presented in this article. The interrelations of stratigraphic units, their lateral variation, the features of lateral fading-out of the Paleocene rocks and angular unconformity in the base of the Eocene rocks are studied. The comparison with Paleogene sections, which are located to the west (Mazanka, Skalistoe, Starosel’e settlements), is done. The geological history of the region in the Paleocene and Eocene is studied as well. At the beginning of the Danian Age, tectonic subsidence marine transgression became the cause of the removal of the relief and the wide spread of shallow-water environments of carbonate sedimentation. The formation of the Simferopol uplift began in the Early Danian. In the Selandian, there was a regression, associated with regional tectonic uplift, the most intense in the area of the Simferopol Uplift. The growth of the Simferopol Uplift continued during Thanet. The end of the Thanet is a time of intense tectonic uplift, which formed the angular unconformity in the base of the Eocene rocks. At the beginningof the Ypresian Age, a transgression, the cause of which was regional tectonic subsidence, occurred. The Simferopol Uplift was an eroded land. In the second half of the Ypresian and Early Lutetian, the Simferopol Uplift was flooded, and on the roof of it, sedimentation began.