R7: Petrology, Mineralogy and Economic geology (Joint session with SRG)

[R7P-01] Mantle-melt interaction at the crust-mantle boundary in the Wadi Tayin massif, the Oman mantle peridotite

*Eiichi Takazawa^1,2, Yumeno Kogure³, keisuke Ishii³, Sayantani Chatterjee¹, Natsuki Oyanagi¹, Katsuyoshi Michibayashi⁴, Yoshihiko Tamura², Oman DP Science Party (1. Niigata Uni. Sci., 2. JAMSTEC, 3. Niigata Univ., Grad. Sch. Sci. Tech., 4. Nagoya Univ.)

Keywords:Oman ophiolite, ICDP, Oman Drilling Project, Moho, Crust-mantle boundary

Hole CM2B in the Wadi Tayin massif of the Oman ophiolite consists of Mantle Sequence (layer thickness 179 m), Dunite with Gabbro Sequence (47 m), and Dunite Sequence (12 m) from bottom to the top. Opx disappears from the harzburgite to the dunite at the boundary between Mantle Sequence and Crust-Mantle Transition associated with a drop of whole rock CaO wt%. Intermediate composition of dunite occurs at this boundary, often accompanied by layers of gabbro and plagioclase. It indicates that the mantle-melt reaction has actively progressed in the lower part of the Crust-Mantle Transition.