Geochemistry and mantle source characteristics of basaltic lavas situated in Seyitgazi (Eskişehir) and Ilıca, Köprüören (Kütahya)

This thesis aims to determine the geochemical properties of the basaltic rocks which are situated in Seyitgazi (Eskişehir) and Ilıca, Köprüören (Kütahya) region and the mantle or crustal sources from which they are derived, and also the geochemical processes effective throughout its evolutionary history. Samples have both alkaline and sub-alkaline nature and they are classified as basaltictrachyandesite, basalticandesite, trachyandesite and andesites. As a result of mineralogical studies, it was determined that the samples contained plagioclase, olivine, clinopyroxene, orthopyroxene and Fe- Ti oxide minerals. The calculated temperature values of the samples are in the range of 1055-1223 0C and the depth values are in the range of 25-12 km and the pressure value is 12 kbar. The primitive mantle normalised multi-element patterns of Seyitgazi basaltic rocks show enrichments in the LILE, relative to the HFS elements and have slightly negative Ta, Nb, P, Ti anomalies whereas Ilıca samples display the LIL element signature which is similar to Seyitgazi samples but distinct from them with the depletion of HFS elements and the enrichments in Pb contents. Samples have low Nb/La, Nb/U and high Ba/Nb, low Zr/Ba and high Ba/La ratios. This ratios suggest that basaltic rocks were derived from a lithospheric source(s) affected by subduction and lithospheric contributions. Moreover, Ilıca and Köprüören samples have high La/Yb(N) content whereas Seyitgazi lavas are represented by higher La/Yb(N) ratios. Tb/Yb(N) ratios of Seyitgazi and Ilıca, Köprüören samples range between 2.2-2.24 and 1.5-1.78 respectively. All these geochemical features suggest that basaltic rocks are originated from either the combined effects of the different degrees of melting in source region with the significant amount of lithospheric contributions or change in the nature of the source in time. Keywords: Basalt, trace elements, geothermometer, geobarometer, Central-West Anatolian