tailieunhanh - Reassessment of the age and depositional environment of the Kırkgeçit Formation based on larger benthic foraminifera, NW Elazığ, Eastern Turkey

The middle-upper Eocene Kırkgeçit Formation, the fossil content of which is the subject of this study, is deposited in a back-arc basin controlled by block-faulting. The Kırkgeçit basin is interpreted as being formed under an extensional regime related to convergence between the Anatolian plate in the north and the Arabian plate in the south. The aim of this study is to reassess the age and depositional environment of the Kırkgeçit Formation by using detailed biometric analysis data obtained from the reticulate Nummulites and determinations of other larger benthic foraminifera (LBF) in the unit. | Turkish Journal of Earth Sciences Turkish J Earth http earth 2021 30 580-600 TÜBİTAK Research Article doi yer-2102-1 Reassessment of the age and depositional environment of the Kırkgeçit Formation based on larger benthic foraminifera NW Elazığ Eastern Turkey Sibel KAYĞILI Department of Geological Engineering Faculty of Engineering Fırat University Elazığ Turkey Received Accepted Published Online Final Version Abstract The middle-upper Eocene Kırkgeçit Formation the fossil content of which is the subject of this study is deposited in a back-arc basin controlled by block-faulting. The Kırkgeçit basin is interpreted as being formed under an extensional regime related to convergence between the Anatolian plate in the north and the Arabian plate in the south. The aim of this study is to reassess the age and depositional environment of the Kırkgeçit Formation by using detailed biometric analysis data obtained from the reticulate Nummulites and determinations of other larger benthic foraminifera LBF in the unit. For this purpose two sections were measured from the latest Bartonian-Priabonian aged unit. Biometric data of the Nummulites hormoensis and Nummulites fabianii from the Kırkgeçit Formation exposures in the northwest of Elazığ has been presented for the first time. In general Nummulites fabianii has robust test with thick walls while Nummulites hormoensis has elongated test with thinner walls in relation to the increase of water depth. The change in embryon size of these reticulate Nummulites has been considered an important indicator for evolution and biostratigraphy. Nummulites hormoensis marks latest Bartonian to early Priabonian SBZ 18 while Nummulites fabianii is a marker for middle-late Priabonian SBZ 19-20 . The Kırkgeçit Formation in the study area was previously dated as late Lutetian-Priabonian based on LBF of it. However by considering the LBF determined in this study the latest .