Facies architecture and depositional evolution of alluvial fan to fan-delta complexes in the tectonically active Miocene Köprüçay Basin, Isparta Angle, Turkey

Abstract

This paper provides the first general account of the facies associations that fill a Miocene fault bounded basin located in the central part of the Isparta Angle (Turkey), in order to define process-controlled sedimentary units reflecting environmental changes in a general tectonic and stratigraphic framework. The northern and western parts of the Köprüçay Basin are occupied by extensive conglomeratic successions belonging to three distinct alluvial fan–fan delta systems (AFD), which pass laterally into pelagic mudstones in the deeper part of the basin. In spite of syn- and post-sedimentary tectonics, most of the sedimentary units still display their original relationships. This allows definition and interpretation of the conspicuous facies changes in the clastic successions according to their position along complete sections across the basin. The bulk of the paper is thus devoted to the description of 11 sub-facies types that have been identified in the three AFDs, and their environmental interpretation. As a result, the origin and sedimentary infill of the Köprüçay Basin appears primarily controlled from Langhian to Tortonian by the N–S trending Kirkkavak Fault. After uplift and erosion of the western part of the basin, the final closure of the Isparta Angle resulted in a westward displacement of the Anatolian block during Upper Tortonian.