Tectono-stratigraphic evolution of the continental miocene basins in Southwest Anatolia

Koç, Ayten
The Tauride range in southern Turkey is flanked and overlain by Neogene sedimentary basins. To the south and on top of the high range, these basins are mainly marine, whereas poorly studied intra-montane basins dominated by continental deposits are exposed to the north. In this study, the stratigraphy and structure of these continental basins which includes Altınapa, Yalvaç and Ilgın Basins are studied. Their stratigraphy of these basins displays poorly expressed fining upwards sequences of fluvio-lacustrine sediments, deposition of which interrupted by regionally correlateable unconformities; they might also have similar hiatuses in each basin. The most prominent unconformity surface occurred during the Middle Miocene and corresponds to a volcanic activity in the region. 40Ar/39Ar dating of the volcaniclastic samples from the Altınapa and Ilgın basins yielded 11.8–11.6 Ma ages. The main basin forming phase was extensional and occurred just before or during the Middle Miocene. The extension directions obtained from paleostress inversion techniques indicate multiple extension directions which are consistent with recent seismic activity and available focal mechanism solutions. The Middle Miocene and onwards extensional history of these basins are consistent with the regional tectonics associated with the Cyprus subduction zone. This suggests that the Cyprus subduction zone has been retreated relative to central Anatolia since, at least, the Middle Miocene time. In addition to extensional history of the region, these continental basins contain evidences for the post-Late Miocene differential uplift of the Taurides in southern Anatolia. These continental basins were very close to sea level during the Middle and Late Miocene and are now lying at an elevation of 1 km. On the other hand, the upper Miocene marine deposits just south of the study area currently lie at an elevation of ~2 km which are elevated ~1 km with respect to these continental basins. We conclude that the current high elevation of the Taurides is related to late Neogene extension and vertical differential uplift possibly due to slab edge processes along the Cyprian Subduction and related mantle processes.