R6：深成岩・火山岩及び サブダクションファクトリー

[R6-04] Petrogenesis of the Khangai granitoids, central Mongolia: Implications for the crustal generation

*Dolzodmaa Boldbaatar¹, Yasuhito Osanai¹, Nobuhiko Nakano¹, Atsushi Kamei², Tatsuro Adachi¹ (1. Kyushu Univ, 2. Shimane Univ)

キーワード：central Mongolia, granitoid, whole-rock Sr–Nd isotopes, Assimilation fractional crystallization (AFC) process

Newly obtained Sr–Nd isotopic data of 267–248 Ma granitoids have a low initial ⁸⁷Sr/⁸⁶Sr ratios between 0.7062 and 0.7283 and characterized by ε_Nd(T) values of -2.13 ~ +1.11 suggests that granitoids may have been derived from a source composed of juvenile material involving AFC processes whereas 238–237 Ma granitoids have high initial ⁸⁷Sr/⁸⁶Sr ratios between 0.7128 and 0.7576 and show ε_Nd(T) values of -1.68 ~ -1.52 suggests that the granitoids may be formed by AFC processes with the interaction between lower crust derived magma and meta-sedimentary rocks.