[S-CG56] ICDP オマーン掘削プロジェクト

[SCG56-18] Comparison of olivine crystal-fabrics between Oman ophiolite peridotites and Supra-subduction zone peridoitites

*道林 克禎¹ (1.名古屋大学 大学院環境学研究科 地球環境科学専攻 地質・地球生物学講座 岩石鉱物学研究室)

キーワード：マントル、かんらん岩、オマーン

The origin of Oman ophiolite is still in debate between the mid-ocean ridge model and the supra-subduction zone model. For the last two decades, we have collected peridotite samples from both ophiolites and the ocean floor and have shown how to quantify CPOs in Vp-Flinn diagram (Michibayashi et al., 2016 EPSL), since olivine crystallographic preferred orientations (CPOs) are key factors to identify the nature of the uppermost lithospheric mantle. In this study, we show similarities and differences of olivine CPOs between the Oman ophiolite peridotites and the others such as Yakuno ophiolites and IBM trench peridotites. The Oman ophiolite peridotites are unique to have axial[100] (AG type) along with typical (010)[100] (A type) and {0kl}[100] (D type) olivine fabrics, whereas the trench peridotites are locally characterized by (001)[100] (E type) and (010)[001] (B type) olivine fabrics.