Tectonic development of an orogen-top rift recorded by its terrestrial sedimentation pattern: The Neogene Eşen Basin of southwestern Anatolia, Turkey

Abstract

The Eşen Basin of southwestern Anatolia formed as a NE-trending intramontane extensional graben, ca. 15 km wide and 30 km long, in the Early Tortonian, after the southeasterly emplacement of the Lycian nappes during the Tauride orogeny. The basin originated due to gravitational collapse of the hinterland zone of the Lycian Taurides in response to the lithospheric thickening caused by microcontinent collision. Sedimentation commenced with the development of basin-margin alluvial fans and a southward-directed axial fluvial system, the latter expanding laterally, changing its channel pattern from braided to meandering and forming floodplain lakes. The isolated ephemeral lakes merged into a single lake at the basin centre, fringed with vegetated mires and desiccated by the end of Miocene time. The second pulse of rifting in the basin, dated to the Early Pliocene, is attributed to the roll-back and outward expansion of the Cretan subduction arc to the south. A new lake rapidly expanded, and the Pliocene deposition of a thick marly succession was terminated by the basinward advance of Gilbert-type deltas and gradual desiccation of the lake in the Late Pliocene. The third pulse of rifting, near the end of the Pliocene, formed new faults, tilted the basin-fill succession and records regional deformation due to the westward tectonic expulsion of the Anatolian craton. The base of the overlying Pleistocene alluvium is an angular unconformity, with fluvial terraces indicating considerable Quaternary uplift. The developmental stages of the Eşen Basin are consistent with the tectonostatigraphic evolution of the adjacent Çameli Basin to the north, which may thus serve as a reference framework for the tectonic history of the region's extensional grabens.