17:15 〜 18:45 [SGC33-P06] Mantle evolution in late Archaean probed by highly siderophile element content ~Constraints from ultramafic volcanic rocks from the Pyradie Formation, Western Australia~ *佐藤 隆1、石川 晃1、上野 雄一郎1、横山 哲也1、Marco Fiorentini2 (1.東京工業大学、2.University of Western Australia)