The origin of enclaves in Emirgazi (Konya) and its surrounding volcanites and their petrological importance in the genesis of regional volcanism

Neogene-Quaternary volcanic rocks outcrop in a wide area extending to Karapınar-Emirgazi-Ereğli in Konya SE. The Neogene aged volcanic rocks represented by the lava flows / domes and their pyroclastics are called "Karacadağ volcanites", also Quaternary intermediate-mafic volcanites are outcropped as scoria cones, lava flows and maar pyroclastics are called ''Karapınar volcanites'' in the study area. These volcanites are the southwestern extension of the Cappadocian Volcanic Providence and were collected under the name of Karapınar-Karacadağ Volcanic Complex (KKVC). Based on the detailed field study, mineralogical (major-trace)-petrographical, geochemical (whole rock-trace element and Sr-Nd-Pb-O isotope) ve geochronological features of the KKVC were investigated. Karacadağ volcanites are calc-alkaline and mainly composed of andesite, rarely basalt, dacite and trachyte. Karapinar volcanites are transitional (calc-alkaline-mildly alkaline) geochemical character and are mainly composed of basalt, rarely basaltic andesite and andesite. In addition, various types of enclaves varying from microscopic to macroscopic dimensions were found in the studied volcanites. As a result of the Ar-Ar geochronology, the age of the basalts of the Karacadağ volcanites is 5.65 ± 0.06 Ma and the age of the dacites is 5.45 ± 0.09 Ma. Data published in the literature show that the volcanism producing Karapınar volcanites is effective from 2.5 Ma to historical periods. In N-MORB-normalized trace element diagrams, investigated volcanites show LILE (Rb, Sr, K) enrichment, negative Nb-Ta and positive Pb anomaly which is typical of orogenic or continental crust contaminated magma. Karacadağ basalts contain Nb/Ta ratios (~ 12) close to Nb/Ta ratios (12-13) in the crust, indicating that the crustal contamination is highly affected. Nb / Ta ratios of the Karapınar basalts (17-19) are close to the chondritic (17.5) value, however considerably higher than the crust. This shows that it is less affected by crustal contamination. KKVC volcanites have 87Sr / 86Sr ratios range between 0.704914-0.706355, 143Nd / 144Nd ratios range between 0.51252-0.51309, 206Pb / 204Pb ratios are between 18.882-18.925, 207Pb / 204Pb ratios are between 15.66-15.72 and 208Pb / 204Pb ratios are between 39.03-39.19. In addition, olivine separation and whole rock 18O analysis data range between 5.7-7.5 ‰ and 7.7-9.5 ‰, respectively. The rocks of the KKVC are generally enriched in terms of Sr-Nd-Pb-O isotopes. The fact that the studied volcanites show quite different mantle reservoirs in Sr-Nd-Pb isotope diagrams is interpreted as an indication of mantle source containing continental crustal components. In particular, changes in Pb isotope contents suggest that they assimilated different crustal materials during their formation. Plotting in the different areas in Sr-Nd-Pb isotope diagrams is interpreted as an indication of mantle source containing continental crustal components and especially changes in Pb isotope contents is interpreted as assimilation of different crustal materials while completing the evolution of the rocks. Especially when the mineral trace element chemistry and isotope geochemistry data are taken into consideration, it is thought that the Neogene aged calc-alkaline and Quaternary aged transitional rocks are genetically related to each other and that they aquired different chemical properties by being exposed to different differentiation processes. According to the hypothetical model in the Pb-O diagrams, it is thought that basalt-1 type rocks can be formed by a binary mixture of a hypothetical mafic end member and 20-35 % crust-1 hypothetical end member and also basalt-2 and 3 type rocks can be formed with the same mafic end member and 15-20 % mixture of crust-2 hypothetical end member. When the trace element data of the olivines from basaltic rocks are examined, it is thought that the KKVC volcanites are derived from the mixture of spinel lherzolithic and pyroxenitic sources contrary to the previous studies. Geochemical and isotopic evidence suggest that, the reaction of asthenospheric mantle and metasomatized and recycled lithospheric mantle has an effect on the formation of the rocks. Dynamic magma chamber processes (magma replenishment, magma mixing etc.) and occurring of enclaves with different type and compositions are thought to played a key role in triggering of the volcanic eruptions. In this study, it is observed that the effect of the continental crust components temporarily decreased from Neogene to Quaternary, however within the Quaternary its effect spatially increased again. Keywords: Asthenospheric Mantle, Crustal Contamination, Enclave, Lithospheric Mantle, Metasomatism, Orogenic, Pyroxenite, Spinel