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Abstract
X-ray diffraction and chemical analyses of lacustrine Oligo-Miocene clay deposits and surrounding rocks in the Sile region northeast of Istanbul, Turkey were conducted to better understand the geologic history of commercially important clay units. Kaolinite is a major constituent, with illite, chlorite, vermiculite, smectite, and mixed-layers also common in the clay deposits that unconformably overlie Paleozoic metasediments, Permian-Triassic Limestones, and Late Cretaceous flysch series and volcanic/volcano-sedimentary rocks. Principal component analysis of elemental concentrations in clays and rocks supports the hypothesis that the lacustrine sediments were derived from highly weathered Paleozoic and Mesozoic sources formed during warm and humid climatic times. Mineral assemblages in the clay deposits were furthered modified by burial diagenetic events and then surface weathering events, initiated with neotectonics in the late Miocene, which continue today in the Earth’s critical zone (the complex near surface environment that includes rock, soil, water, air, and living organisms regulating life-sustaining resources).