Tectonosedimentary development and palaeoenvironmental changes in the Acıgöl shallow-perennial playa-lake basin, SW Anatolia, Turkey

Authors: CAHİT HELVACI, MEHMET CİHAT ALÇİÇEK, İBRAHİM GÜNDOĞAN, ÜNSAL GEMİCİ

Abstract: The late Cenozoic extensional deformation formed several NE-trending fluvio-lacustrine basins in SW Anatolia, filled by alluvial, fluvial and lacustrine deposits. Among them, the Acıgöl basin , is notable for its tectono-sedimentary development of a prominent shallow-perennial playa-lake setting. The basin initially subsided to receive coarse-clastic alluvial deposits, merging into fluvial systems and central shallow lakes. Subsequent basin deepening with significant sediment supply from surrounding basement horsts caused gradual shrinkage of the relatively small shallow lakes, due to renewed progradation of alluvial fans and they eventually dried out completely. The sedimentation pattern and palaeoenvironmental changes record a constant tectonic, sedimentation, climatic and lake chemistry interaction from the late Miocene onward, with close relation to the coeval adjacent basins. The modern Acıgöl Lake was formed by progressively inward narrowing and deepening caused by the activity of the basin bounding faults and eventually by newly generated synthetic and antithetic fault systems. The modern depression is a typical shallow-perennial playa-lake basin with active evaporation and dominant precipitation of sodium sulphates, Mg-Ca carbonates and clay minerals. In this study three deep bore-hole logs of the recent drilling completed in the modern Acıgöl lake plain were examined to document the mode of deposition and development of the basin. The bore-hole logs show that the Acıgöl basin was gradually transformed from a perennial deep lake into shallow perennial/ephemeral playa settings.

Keywords: Neotectonic extension, Acıgöl, playa-lake, evaporite, Na sulphate, SW Anatolia

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