Geomorphological insight into changing tectonic regime, Pasinler Basin, Turkey

Abstract

The Pasinler Basin, in the East Anatolian Contractional Province, features a suite of geomorphological zones, visible in the field, air photographs and Landsat and SRTM DEM imagery. These zones reflect past and current tectonically influenced processes. Collins et al: Geomorphological insight into changing tectonic regime, Pasinler Basin, Turkey. 2 of 26 Remnants of the Erzurum-Kars plateau representing Mio-Pliocene volcanism, associated with transtensional tectonics, have been modified by two stages of drainage development: an earlier, shallow valley network, which was modified following uplift and tilting to form the present system characterised by deep narrow valleys that supply alluvial fan complexes. These fans discharge onto the present, aggradation-dominated basin floor. Initial normal faulting induced massive slope failures on the basin’s northern margin. This extensional phase within the basin was reversed by the Late Pleistocene, with thrust faults modifying and producing landforms, and affecting sediment sequences, along both the north and south basin margins. The shift from a transtensional regime and associated volcanism to normal faulting in the Pliocene-Early Pleistocene, and then to the present compression-dominated regime appears to correspond with regional tectonic changes resulting from collision of the Arabian microplate and the subsequent westward movement of the Anatolian microplate.