Reconstructing the geometry of central Anatolia during the late Cretaceous: Large-scale Cenozoic rotations and deformation between the Pontides and Taurides

Abstract

The Central Anatolian Crystalline Complex (CACC) exposes metamorphic, ophiolitic and igneous rocks that were formed and deformed during closure of the Neotethyan ocean. The CACC is located in central Turkey, between the Pontides in the north and the Taurides in the south, separated by major fault zones. Composite plutons intruded the meta-sedimentary and ophiolitic units between ∼95 and 75Ma, and form linear magmatic belts (∼100km long) along the western and northern margins of the CACC. Exhumation of the metamorphic and igneous complex was finalized by the Paleocene time. In this study, we paleomagnetically study fifteen plutons spanning the entire non-deformed upper Cretaceous granitoid belt to test whether the initial configuration of the CACC was modified by vertical axis rotations after its exhumation. Our results show three internally coherent domains with significantly different vertical-axis rotations: (1) in the north-east, the Akdağ–Yozgat block (AYB) records ∼15° clockwise rotation, (2) in the north-west, the Kırşehir–Kırıkkale block (KKB) shows ∼6–9° counterclockwise rotation and (3) in the south-west, the Ağaçören–Avanos block (AAB) shows 28–35° counterclockwise rotation. We propose that these rotations were accommodated by two transpressional fault zones: in the south, the existing Savcılı Thrust Zone between the AYB and KKB and in the north, the newly introduced Delice–Kozaklı Fault Zone between the KKB and AAB. The restored configuration of the CACC suggests that the three blocks were largely aligned in a ∼NNE orientation at an early stage of their history. Consequently, since the late Cretaceous the shape of the CACC was affected by large scale deformation, resulting in its modern triangular geometry. This deformation phase is best explained as a result of collision of the CACC with the Pontides.