Mineralogical and geochemical i̇nvestigation of the sedimentary units around Eskişehir - Alpu

The aim of this study is to determine the mineralogical and geochemical characteristics of Miocene aged sedimentary units in Eskişehir- Alpu region and to determine the formation conditions of neoformation minerals. In the study area, basement rocks consisting of metamorphics and ophiolites with Neogene aged sedimentary units are observed. Neogene age sedimentary units rests upon the basement rocks unconformably composed of, from older to younger, M1 unit, M2 unit and M3 Unit. All units unconformaly overlain by the Quaternary alluvium. Mineralogical composition of the samples were detected by X-Ray Diffraction method. Analyses show that there are dolomite, calcite, feldspar, mica, Opal-CT, magnesite, quartz, siderite and clay minerals in the samples. The Na, Mg, Ca contents of dolomites indicate that they are precipitated in a saline and alkaline environment. Smectites which are the most common clay minerals are thought to be formed as the result of the transformation of detrital materials. The well-developed crystallinity of the illite minerals suggest that it is of detrital origin and is derived from the metamorphic rocks. The results of geochemical analysis indicate that the sediments in the study area are derived from felsic magmatic rocks. Sediments are located in the active continental margin and continental island arc region which have the continental conditions. Keywords: Eskişehir, Alpu, Geochemistry, Mineralogy, Carbonate, Clay