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[SCG58-P20] Water-rock reaction in a hydrated ductile shear zone across the Moho Transition Zone in Oman ophiolite
Keywords:Oman ophiolite, Moho Transition Zone, Crust-mantle boundary, Water-rock reaction, Ductile shear zone
The oceanic plate experiences a variety of fault movement before subducting from the trench into the deep mantle, including transform faults, normal faults at the mid-ocean ridge, the outer rise, and detachment faults of the Megamullion. During these tectonic processes, seawater infiltrates along the faults, resulting in water-rock reactions within the oceanic plate, which would have a significant impact on the rheology of the oceanic plate. In this study, we focused on a ductile shear zone developed with large amounts of hydrous minerals in the northern Fizh massif, Oman ophiolite.
Oman ophiolite was formed by obduction of the Tethys oceanic plate onto the Arabian Peninsula during the Cretaceous (Coleman, 1981), so that several shear zones have been developed during obduction (Boudier et al., 1988). In particular, a ductile shear zone in the northern Fizh massif occurs with large amounts of hydrous minerals in the Moho transition zone, where is a crust-mantle boundary (Michibayashi and Oohara, 2013). Hydrous mineral assemblages in the shear zone have been classified into five sub-zones: Amp-Pl sub-zone consisting of amphibole and plagioclase, Ol sub-zone consisting of olivine, Amp sub-zone consisting of amphibole, chlorite, and serpentine, Chl sub-zone consisting of chlorite, and Cpx sub-zone consisting of clinopyroxene (Natsume et al., 2022). In this study, we consider the influence of fluid and element transfer during hydrous mineral formation, and discuss microstructural development of a hydrated ductile shear zone occurred at a crust-mantle boundary in oceanic plate.
References
Boudier et al., 1988, tectonophysics, 151, 275-296.
Coleman, 1981, J. Geophys. Res., 86, 2497-2508.
Michibayashi and Oohara, 2013, Earth Planet. Sci. Lett., 377, 299-310.
Natsume et al., 2022, JpGU2022, SCG56-P01.
Oman ophiolite was formed by obduction of the Tethys oceanic plate onto the Arabian Peninsula during the Cretaceous (Coleman, 1981), so that several shear zones have been developed during obduction (Boudier et al., 1988). In particular, a ductile shear zone in the northern Fizh massif occurs with large amounts of hydrous minerals in the Moho transition zone, where is a crust-mantle boundary (Michibayashi and Oohara, 2013). Hydrous mineral assemblages in the shear zone have been classified into five sub-zones: Amp-Pl sub-zone consisting of amphibole and plagioclase, Ol sub-zone consisting of olivine, Amp sub-zone consisting of amphibole, chlorite, and serpentine, Chl sub-zone consisting of chlorite, and Cpx sub-zone consisting of clinopyroxene (Natsume et al., 2022). In this study, we consider the influence of fluid and element transfer during hydrous mineral formation, and discuss microstructural development of a hydrated ductile shear zone occurred at a crust-mantle boundary in oceanic plate.
References
Boudier et al., 1988, tectonophysics, 151, 275-296.
Coleman, 1981, J. Geophys. Res., 86, 2497-2508.
Michibayashi and Oohara, 2013, Earth Planet. Sci. Lett., 377, 299-310.
Natsume et al., 2022, JpGU2022, SCG56-P01.