Determination of pattern, timing and mechanism of the active tectonic deformation in the western flank of the Central Taurides

Abstract

The Central Taurides is located in the southern margin of the Central Anatolian Plateau and corresponds to the upper crust of the subduction between African and Anatolian plates, with a high relief of up to 2 km. This mountainous region has distinctive geomorphological features and presents a unique setting to investigate the mechanism of orogenic plateau margin development related to subduction and topographic evolution around the Eastern Mediterranean. Here, we combine new kinematic data from exposed fault planes, tectonic landforms from high-resolution digital elevation models, microstructural analysis and U-Th and U-Pb geochronology on syn-tectonic calcites to elucidate the pattern, mechanism and timing of active tectonic deformation in the western Central Taurides, above the Cyprus Subduction Zone. Our geomorphic analyses reveal a post-orogenic transient actively deforming topography. The geomorphic markers constrain long-term surface uplift pattern with a mean cumulative surface uplift of 1,710 ± 50 m and shows an increasing trend from west to east, from 1,600 ± 50 to 1,800 ± 50 m. Our results suggest a dome-like uplift pattern in the west-east direction across the southern margin that reaches up to maximum cumulative uplift values in the quadrangle of Alanya-Başyayla-Ermenek-Gazipaşa. Our kinematic measurements on the exposed fault planes reveal the presence of normal, strike-slip, and thrust/reverse faults, indicating a multiphase history of brittle deformation. Microstructural studies on syn-tectonic calcites show brittle deformation features such as microcracks, brecciation, and calcite twinlets, providing evidence of tectonic control over calcite precipitation. U-Th ages of fault-related calcites show continuous normal faulting from the Middle/Late Pleistocene to the Holocene due to NE-SW horizontal extension, with a conspicuous clustering at circa 450 ka, indicating a connection/coupling between deep-seated and surface processes. It suggests that extensional deformation and rapid surface uplift may occur concurrently, creating relief-bounding normal fault zones and high-relief dynamic landscapes on a short timescale in the overriding plates. The U-Pb carbonate geochronology of syn-tectonic calcite samples indicates three distinct phases of faulting from the Late Cretaceous to the Quaternary. Thrust/reverse faulting events, which represents the first faulting phase, were observed in the Late Cretaceous. The second faulting phase, strike-slip faulting, occurred from the Early Eocene to the Early Miocene with a clear cluster in the Oligocene. Normal faulting was the last faulting phase and is prevalent from the Early Miocene to the Quaternary. The Late Cretaceous thrust/reverse faulting could be associated with the collision of different tectonic blocks in Anatolia. The Oligocene strike-slip shearing in the region was probably driven by the convergence and collision of tectonic plates in Eastern Anatolia and the resulting block rotations in Southern Türkiye. The onset of normal faulting in the Early Miocene indicates a shift towards extensional tectonics during the Oligocene-Miocene transition, which continuous until the present day. The last faulting phase has been possibly driven by the coupling geodynamic processes such as slab retreat, slab deformation and mantle upwelling associated with convergence along the Cyprus Subduction Zone. Our findings have significant implications for understanding the morphotectonic evolution and post-orogenic deformation in the plateau margins and geodynamic evolution of the Eastern Mediterranean.