Multiple rifting pulses and sedimentation pattern in the Çameli Basin, southwestern Anatolia, Turkey

Abstract

The neotectonic development of western Anatolia was characterized by the formation of numerous graben-type basins, which have been well documented by general mapping, although the cause and timing of the Neogene regional tectonic extension remain controversial. Previous interpretations of the origin and evolution of these Neogene basins were based mainly on regional-scale tectonic inferences, rather than detailed basin-fill analysis. The present study of the terrestrial intramontane Çameli Basin in the western Taurides combines detailed facies analysis with biostratigraphic dating (mammalian and molluscan fossils) and documents three pulses of crustal extension that are reflected in changes in the palaeogeography and sedimentary architecture of the basin. Development of the Çameli graben commenced in the Vallesian time (early Tortonian), and is marked by alluvial-fan, fluvial and lacustrine depositional systems, with freshwater molluscan fauna. A second pulse of tectonic extension occurred in the late Ruscinian time (early–middle Pliocene), producing a new normal fault that split the basin longitudinally into two compartments. The lake environment expanded and deepened, coastal peat-forming mires developed and abundant mammal fauna appeared by the early Villanian time (middle Pliocene), with the lacustrine deposits onlapping the basin-margin and intrabasinal fault escarpments. The lacustrine environment subsequently shrank, as the progradation of axial river deltas and basin-margin fan deltas caused water shallowing and shoreline regression. A third pulse of extension occurred at the end of Villanian time (late Pliocene), when the development of a new generation of normal faults further split the basin into still narrower half-graben compartments. The third pulse of rifting is estimated to have accounted for little more than 10% of the sub-basinal crustal extension, but caused the most striking changes in the basin palaeogeography and drainage pattern. The inward development of the successive normal faults indicated a high-rate crustal extension. This is the first regional case study of a terrestrial neotectonic graben employing detailed sedimentary facies analysis and mammal biostratigraphy and providing a time-stratigraphic framework for the rifting pulses in western Anatolia.