FOREARC AND FORELAND BASIN EVIDENCE FOR PROTRACTED LATE CRETACEOUS-EOCENE COLLISION IN WESTERN ANATOLIA

Across the Alpine-Himalayan orogeny, the timing of intercontinental collision is difficult to determine and often disputed by ~15 to 40 Myr. This has led to a variety of contradictory paleogeographic and geodynamic reconstructions. In Anatolia, the closure of the Neotethys Ocean and collision along the >1,700 km long Izmir-Ankara-Erzincan suture zone has been proposed to occur sometime from the Late Cretaceous through Eocene. Forearc-to-foreland basins across northern Anatolia preserve a near-continuous depositional record during subduction and collision, and therefore offer unparalleled insight into the evolution of continental collisions. Here we present sedimentary provenance results from Late Cretaceous through Eocene strata in the forearc-foreland basins of western Anatolia. We compare these results to published data from across Anatolia to evaluate the regional response to intercontinental collision. The appearance of lower plate detritus, ophiolitic material and sediment recycling in the forearc preceded thick-skinned deformation and molasse deposition by ~20 Myr, demonstrating a protracted collisional evolution. We synthesize these results into a new scenario for Izmir-Ankara-Erzincan suturing by proposing several geodynamic mechanisms to explain multi-phase intercontinental collision.