Clay mineralogy and paleoclimatic properties of the neogene deposits in sinanpasa basin (Afyon-Western Anatolia)

Abstract

The Sinanpasa basin, one of the Neogene basins formed in the extensional tectonic regime in Western Anatolia, is located on the eastern margin of Western Anatolia basins containing different types of evaporites, lignite, uranium and clay minerals. Miocene sequence was initiated with alluvial fan-fluvial units and followed by lacustrine sediments. River floodplains and lakeshore marshes locally contain economic coal levels. Since Middle-Late Miocene, the products of Afyon volcanism were deposited into a subaerial or a subaqueous environment alternating with lake sediments. Dominant clay minerals are illite and smectite within the sediments coexistence with the volcanics. These minerals were accompanied by chlorite, kaolinite, and zeolite in some samples. Feldspar, dolomite, thenardite, and gypsum are locally observed too. Sepiolite mineral enrichments are also noteworthy in shallow-coastal lacustrine environments where organic matter is abundant. Clay minerals are mostly detritic and developed due to the weathering of volcaniclastics and sedimentary rocks in temperate/humid climatic conditions. In particular, smectite and kaolinite minerals were formed in situ/authigenic under subaqueous conditions due to the acidic/basic character of tuffs. As a result, different clay mineral types have been developed due to the mineralogical composition of source rocks, climatic factors (humid/semi-humid, arid), paleotopography, depositional environment and diagenetic factors.