Japan Geoscience Union Meeting 2021

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[J] Oral

S (Solid Earth Sciences ) » S-CG Complex & General

[S-CG44] Petrology, Mineralogy & Resource Geology

Sun. Jun 6, 2021 1:45 PM - 3:15 PM Ch.23 (Zoom Room 23)

convener:Koichi Momma(National Museum of Nature and Science), Yu Nishihara(Geodynamics Research Center Ehime University), Tatsuo Nozaki(Submarine Resources Research Center, Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology), Nobutaka Tsuchiya(Department of Geology, Faculty of Education, Iwate University), Chairperson:Yu Nishihara(Geodynamics Research Center Ehime University), Koichi Momma(National Museum of Nature and Science), Tatsuo Nozaki(Submarine Resources Research Center, Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology)

2:15 PM - 2:30 PM

[SCG44-03] ZIRCON U–Pb AGES AND GEOCHEMISTRY OF GRANITOIDS FROM SOUTHWEST MONGOLIA

*Dolzodmaa Boldbaatar1, Yasuhito Osanai1, Nobuhiko Nakano1, Tatsuro ADACHI1, Ippei Kitano1, Kundyz Syeryekhan2 (1.Kyushu University, 2.Golden Hill LLC)

Keywords:I-, S-type granite, zircon U–Pb age, SW Mongolia

We present new petrographic, geochemical and geochronological data for granitic rocks emplaced in the Altai (Mongolian Altai) terrane of southwest Mongolia. The data are used to constrain their evolution and to discuss the tectonic implications for the Altai terrane. The zircon U–Pb ages indicate that the magmatism can be divided into three stages: stage 1 (397–366 Ma), stage 2 (340-300 Ma) and stage 3 (208-200 Ma). The stage 1 granitic rocks are divided into two types: Bt–Hbl granites having I-type affinity with volcanic arc signature and Crd–Grt bearing Bt–Ms granites having S-type affinity. On the other hand, Stage 2 Qz–Bt syenite having shoshonitic affinity and stage 3 Kfs-porphyritic Bt granites having high-K calc-alkaline affinity with intraplate tectonic setting.