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In the Isparta Province (SW Anatolia), the Golcuk volcanism comprises of many medium-to-small volume trachyte, trachyandesite, basaltic trachyandesite, phonolite, lamprophyre dome and dykes, and pyroclastic deposits. The domes and dikes together with the explosive volcanism have been occurred at various time intervals throughout the geological history and contain three groups of xenoliths felsic, mafic, and ultramafic. Felsic xenoliths with syenitic and syeno-dioritic composition have inequigranular textures. Mafic xenoliths consist of inequigranular textured gabbroic and monzodioritic rocks. The third group is ultramafic xenoliths with pyroxenitic, equigranular textures. The Golcuk volcanic rocks have intermediate to basic compositions, having shoshonitic to ultrapotassic characteristics. Major element modeling shows that fractional crystallization is the main petrogenetic process in the evolution of the magma. They have high large ion lithophile (LIL) element (Th, K, Sr, Ba) concentrations but are low in high field strength (HFS) element (Nb, Ta, P, Ti, Zr). The extreme depletion in the elements indicates that there is a partially modified mantle source with a subduction. All rocks are enriched in light rare earth elements (LREE) and do not show any Eu anomaly. For this reason, it is generally thought that all rocks (xenolith types and host rocks) were formed from similar magma. The magma rise to shallow magma chamber formed of fractional crystallization from a deep magma chamber before eruption. |
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