The discovery of a low-angle normal fault in the Taurus Mountains: the İvriz detachment and implications concerning the Cenozoic geology of southern Turkey*

Abstract

The Ivriz detachment fault has been determined on the southern border of the Ulukisla basin separating the metamorphic Bolkar Group of the Taurus Mountains and the Paleocene-Lower Eocene Halkapinar formation of basin deposits. The fault dips towards the north and has kinematic indicators (asymmetric grain/grain aggregate porphyroclasts, oblique foliation, and S-C fabrics), suggesting a top-to-the-N-NE sense of shearing. The clastic material originating from the Bolkar Group in the sedimentary units of the Ulukisla basin demonstrates that the detachment fault could have been be active during Latest Cretaceous-Eocene times. The Ivriz detachment may have initiated as part of a high-angle breakaway fault (the Aydos main breakaway fault) in the south of the Ulukisla basin. The breakaway fault then rotated to a low-angle normal fault and its northern continuation played an important role in the exhumation of the Central Anatolian Crystalline Complex. This implies that the Upper Cretaceous-Eocene sedimentary basins in central Anatolia were supradetachment basins rather than collision- or arc-related basins as previously suggested.