First micropalaeontological record from the early and middle Eocene Mamuca Formation of the Dümrek Basin, western Central Anatolia, Turkey: Biostratigraphy, depositional history and palaeoclimate

Abstract

This study presents the stratigraphy, biostratigraphy and palaeoecology of a 420- m thick sequence of the Mamuca Formation (Dümrek Basin, Eskis¸ehir, Turkey). The age for the strata of the Mamuca Formation in the Çakıro˘glu Creek section is narrowed to late Ypresian-Lutetian (early-middle Eocene) by benthic foraminifera (Nummulites planulatus, N. burdigalensis, Assilina placentula, A. laxispira and A. cuvillieri), planktonic foraminifera (Acarinina bulbroki, Acarinina rohri and Acarinina topilensis) and ostracoda (Eopaijenborchella longicosta and Bairdia gliberti). The sedimentation started in coastal conditions and changed basinward into a shallow marine environment. The palynological assemblage is documented by frequency of palms Spinizonocolpites, Proxaperties and Longapertites, and unknown botanical affinity of Psilodiporites iszkaszentgyoergyi linking them to mangrove environments, along with pteridophytic spores indicating coastal sedimentation. Subsequently, a relative sealevel rise is obvious, leading to a sharp increase in the abundance of organic-walled dinocysts and a decrease in mangroves, almost died-off. The following faulting caused a tectonically triggered subsidence of the basin and led to an environment that deepened even more, provided that it was still shallow marine conditions that allowed the accumulation of coarse-grained sediments, devoid of fossil. Palynological data, stable isotopes (δ18O and δ13C) and quantitative palaeoclimate estimates point to a warm (probably tropical) and humid climate during the late Ypresian and Lutetian.