Cengiz Yildirim

Late Pleistocene intraplate extension of the Central Anatolian Plateau, Turkey: Inferences from cosmogenic exposure dating of alluvial fan, landslide and moraine surfaces along the Ecemiş Fault Zone

Here we documented the vertical displacement, slip rate, extension rate, and geochronology of normal faults within a narrow strip along the main strand of the Ecemis Fault Zone. The Kartal, Cevizlik, and Lorut Faults are normal faults that have evident surface expression within the strip. Terrestrial cosmogenic nuclide geochronology revealed that the Kartal Fault deformed the 104.2 ± 16.5 ka aged alluvial fan surface and the Cevizlik Fault deformed the 21.9 ± 1.8 ka old moraine and talus fan surfaces. Our topographic surveys indicated 120 ± 10 m and 13.1 ± 1.4 m surface-breaking vertical displacements along the Kartal and Cevizlik Faults, respectively. Accordingly, we suggest a 1.15 ± 0.21 mm a−1 slip rate and 0.66 ± 0.12 mm a−1 extension rate for the last 104.2 ± 16.5 ka on the Kartal Fault, and a 0.60 ± 0.08 mm a−1 slip rate and 0.35 ± 0.05 mm a−1 extension rate for the last 21.9 ± 1.8 ka on the Cevizlik Fault. We believe that these structures are an integral part of intraplate crustal deformation in the Central Anatolia. They imply that intraplate structures such as the Ecemis Fault Zone may change their mode through time; presently, the Ecemis Fault Zone has been deformed predominantly by normal faults. The presence of steep preserved fault scarps along the Kartal, Cevizlik, and Lorut Faults point to surface-breaking normal faulting away from the main strand and particularly signify that these structures need to be taken into account for regional seismic hazard assessments.

Multiple Exhumation Phases in the Central Pontides (N Turkey): New Temporal Constraints on Major Geodynamic Changes Associated With the Closure of the Neo‐Tethys Ocean

The Central Pontides of N Turkey represents a mobile orogenic belt of the southern Eurasian margin that experienced several phases of exhumation associated with the consumption of different branches of the Neo-Tethys Ocean and the amalgamation of continental domains. Our new low-temperature thermochronology data help to constrain the timing of these episodes, providing new insights into associated geodynamic processes. In particular, our data suggest that exhumation occurred at (1) ~110 to 90 Ma, most likely during tectonic accretion and exhumation of metamorphic rocks from the subduction zone; (2) from ~60 to 40 Ma, during the collision of the Kirşehir and Anatolide-Tauride microcontinental domains with the Eurasian margin; (3) from ~40 to 25 Ma, either during the early stages of the Arabia-Eurasia collision (soft collision) when the Arabian passive margin reached the trench, implying 70 to 530 km of subduction of the Arabian passive margin, or during a phase of trench advance predating hard collision at ~20 Ma; and (4) ~11 Ma to the present, during transpression associated with the westward motion of Anatolia. Our findings document the punctuated nature of fault-related exhumation, with episodes of fast cooling followed by periods of slow cooling or subsidence, the role of inverted normal faults in controlling the Paleogene exhumation pattern, and of the North Anatolian Fault in dictating the most recent pattern of exhumation.