S1, S4: Earth materials science related to igneous processes and plate convergence region (Joint Special Session)

[S1,S4-05] Influence of pore geometry and alteration minerals on seismic wave velocities of Epidosite collected from the Oman Drilling Projects

*Kumpei Nagase¹, Ikuo Katayama¹, Kohei Hatakeyama², Yuya Akamatsu¹, Keishi Okazaki³ (1. Hiroshima Uni. Sci., 2. Meisei Uni. , 3. JAMSTEC)

Keywords:Epidosite, Pore geometry, Seismic wave velocities

In the upper part of the oceanic crust (Layer 2), where seismic wave velocity is slow, much water exist in cracks (e.g., Detrick et al., 1994). However, an low Vp/Vs region has been observed at the bottom of Layer 2 (Spudich and Orcutt, 1980), and it cannot be explained by cracks alone. There are two candidates that may explain : (1) rounded pore with large aspect ratio and (2) effect of hydrothermal alteration. In this reserch, we studied the physical properties and microstructure in epidosite.