S2: Water Rock Interaction (Special Session)

[S2P-02] Alteration processes of oceanic mantle inferred from serpentinization in the Salahi mantle section, the Oman Ophiolite

Yohki Yoshiba², *Eiichi Takazawa^1,3, Main Tokinaga² (1. Niigata Univ, Sci., 2. Niigata Univ. Grad. Sch. Sci. Tech., 3. JAMSTEC)

Keywords:serpentinization, upper mantle, peridotite, oceanic lithosphere, Oman ophiolite

This study reports serpentinization in the Salahi mantle section of the Oman Ophiolite to discuss the initial stage of water infiltration into the uppermost mantle. We found the ubiquitous occurrence of antigorite and talc in the Salahi mantle section. The presence of antigorite veins and their morphology suggest that hydrothermal fluids infiltrated along fractures. The less occurrence of antigorite and talc in the northwestern part of the Salahi mantle section may indicate that the penetration of hydrothermal fluids was somehow restricted at the center of the ridge segment.