Non-marine sedimentation associated with Oligocene-Recent exhumation and uplift of the Central Taurus Mountains, S Turkey

Abstract

Three related basins in southern Turkey, the Ecemiş Basin, the Karsanti Basin and the Aktoprak Basin, document the Neogene-Recent regional exhumation and surface uplift history of the Central Taurus Mountains. The regional tectonic framework was established by a Late Eocene phase of compressional deformation that ended Tethys-related marine deposition. During the Oligocene–Early Miocene non-marine sedimentation was dominantly from braided rivers flowing from the nascent Taurus Mountains and from the Niğde metamorphic massif further north. During this period erosion more or less kept pace with exhumation and the topography remained subdued, allowing a marine incursion (probably eustatically controlled) into the Karsanti Basin in the east during Early Oligocene time. Regional exhumation was possibly controlled by thermal uplift of an actively extending area located behind the subducting S-Neotethys in the Eastern Mediterranean Sea. During exhumation, largely ophiolitic rocks were eroded, revealing the deformed Mesozoic Tauride carbonate platform beneath. The area was affected by a short-lived pulse of compressional deformation/transpression, probably in Mid-Miocene time, but extensional exhumation then resumed, as indicated by the presence of metamorphic-derived clasts from the adjacent Niğde Massif. Late Miocene deposition was dominated by large inward-draining lakes, consistent with regional evidence of a humid climate during this time. Strong surface uplift took place during Plio-Quaternary time. Drainage to the Mediterranean became established, allowing river valleys to incise deeply into the flanks of the Taurus Mountains. Palaeo-valleys were successively infilled with coarse alluvial sediments. This deposition was influenced by NE–SW trending extensional faults. In addition, the sedimentary evolution of the area was strongly influenced by the NNE–SSW trending Ecemiş Fault Zone, which has experienced ca. 60 km of left-lateral strike-slip since the Late Eocene. An important pulse of normal faulting/transtension in latest Miocene–early Pliocene time generated large fault scarps. These acted as sources for large Plio-Quaternary alluvial fans, which prograded across active strike-slip faults. The morphology of these fans was influenced by a combination of Quaternary climatic change, axial-fluvial downcutting and active strike-slip tectonics. In general, the Plio-Quaternary regional uplift of the Taurus Mountains may relate to underplating of material derived from the African plate during progressive collision with the Anatolian (Eurasian) plate in the vicinity of the easternmost Mediterranean Sea.