Geochemical Study of Collision Volcanism at the Plate Boundary in Turkey -Comparison With Subduction Volcanism in Japan-

点击翻译按钮获取中文摘要

All these geochemical data show that there are inhomogeneity in the upper mantle structure related with the plate tectonics in Turkey. In the eastern part, Sr isotopic rations of Karacadag are low, suggesting the less contribution of magma-crust interaction. Sr isotopes for the volcanoes in the lake Van area vary locally. The Sr rations of Nemurut have a correlation with SiO_2 contents, indicating the crustal contamination. He isotopes in this area is higher than that of air, and suggest the presence of mantle He. The value of mantle He is the same as that in the subduction area, suggesting that the He isotopes are the same in both subduction and collision area. In the central part of Turkey, Sr isotopes of Erciyes and Hasan are 0.7038-0.7058 which are in the range of the subduction area. He isotopes show the higher degree of crustal contamination than that in the eastern Turkey. In the western Turkey, the radiogenic ^4He was observed in all over the geothermal area in the Aegean coast. However, the high high ^3He/^4He ratios and low carbon isotopes are obtained in Kula, where Sr isotopes are also very low (0.7030-0.7035). Kula seem to be very special if it is on the extension of Aegean island arc. It should be necessary to examine the Aegean arc in future in comparison with this study.