R6: Plutonic rocks, volcanic rocks and subduction factory

[R6-05] Zircon U-Pb dating of granitoids in the Hobenzan area, western Yamaguchi Prefecture, southwest Japan

*Yukiyasu TSUTSUMI¹, Kenichiro TANI¹ (1. National Museum of Nature and Science)

Keywords:SW Japan, San-yo Province, Cretaceous, granitoid, zircon U-Pb age

Zircons U-Pb ages were obtained from granitoids in the Hobenzan area, western Yamaguchi Prefecture, southwest Japan. Granitoid bodies in the area consist of granodiorite and granite. The 5 granodioritic samples indicate 95.4 ± 0.7 Ma, 96.3 ± 1.0 Ma, 96.3 ± 0.8 Ma, 96.2 ± 0.6 Ma and 97.1 ± 0.7 Ma whereas the 2 granitic samples indicate 93.9 ± 0.7 Ma and 90.2 ± 0.8 Ma. Errors are 95% confidence intervals. These ages are equivalent of the granitoids in northern Kyushu, but there is no report for granitoid which age is more than 95 Ma from eastern Chugoku District. Additional research is necessary to verify the chronological continuation of granitoids in SW Japan.