[M-IS23] Developments and applications of non-destructive analyses in natural archives

[MIS23-P01] Non-destructive analysis of sediment cores collected on the southwestern flank of the Shatsky Rise during Cruise KH-24-1

*Erika Tanaka¹, Junichiro Kuroda², Kazutaka Yasukawa³, Jin-Oh Park², Katsura Kameo², Ryoji Toda², Koichi Iijima⁴, Yoichi Usui⁵, Yusuke Kuwahara³, Mitsuki Ogasawara³, Yuuchi Ikezu³, Haruyuki Ijichi³, Yusuke Hatakeyama³, YUE SUN², FAN YU², Yuqi Lyu², Noboru Yamakawa², Yang ZHAO², Yuki Nakagawa⁶, Yuki Yoshizumi¹, Ryunosuke Isoda⁵, Juri Uda ⁷, Futa Honda⁷, Soya Ito⁷, Yoshiki Horiuchi⁸, Ritsuko Sawada⁹, Mako Nakao¹⁰ (1.Kochi University, 2.Atmosphere and Ocean Research Institute, The University of Tokyo, 3.School of Engineering, The University of Tokyo, 4.Japan Agency for Marine-Earth Science and Technology, 5.Kanazawa University, 6.School of Science, The University of Tokyo, 7.Chiba University, 8.Nippon Maritime Enterprises, Ltd., 9.Marine Works Japan Ltd., 10.MOL Marine & Engineering Co., Ltd.)

Keywords:Shatsky Rise, Deep-sea sediments, Pleistocene, X-ray CT, MSCL

Shatsky Rise is a large igneous province (LIP) in the western North Pacific Ocean, which formed between 147 and 124 million years ago. Its summit reaches 1950 m below sea level (mbsl) whereas the depth of the deep-sea basin around Shatsky Rise is 5500–6000 mbsl [1]. Since Shatsky Rise is situated within the North Pacific subtropical gyre and on the course of the westerlies, nutrient supply around the Shatsky Rise has been attributed to surface current (i.e., Kuroshio Extension and Oyashio Current) and intensified westerlies transporting eolian dust [2–5].
Recently, the nutrient supply system around the Kuroshio area and in the oligotrophic gyre southern off the Shatsky Rise has been reevaluated, considering deep-sea turbulence and upwelling involving the interaction of bottom water current and “topographic high” [6, 7]. However, observations have not verified that such a huge topography can function as a physical barrier to supply nutrients to the surface ocean from the deeper layer. Notably, previous ocean drilling on the southwestern flank of the Shatsky Rise confirmed a sedimentary hiatus between the Pliocene and Cretaceous, implying the existence of strong bottom currents in this area [8].
Therefore, Cruise KH-24-1 aimed to reveal the relationships between depositional environments and paleoceanographic changes, including the intensification of the bottom current, on the southwestern flank of the Shatsky Rise. During Cruise KH-24-1, we conducted piston and multiple coring and CTD observations. These sediment samples are considered to cover the last 500 kyrs. In this presentation, we will introduce the preliminary results of Cruise KH-24-1, focusing on the non-destructive analysis (X-ray CT and MSCL) of the sediment cores and discussing the possibility of further research related to CTD observations.

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