[M-IS18] Marine manganese deposits: Origin, growth processes, and environments

[MIS18-P01] Microtopographies around southwestern ridge of Takuyo-daigo seamount obtained by AUV "Urashima"

*Koichi Iijima^1,2, Yuka Masaki^1,2, Blair Thornton³, Akira Usui⁴, Keisuke Nishi⁵, Katsuhiko Suzuki^1,2, Kazuya Kitada^1,2, Junji Kaneko^1,2, Cruise members of YK15-15, Cruise members of NT13-13, Cruise members of KR15-E01, Cruise members of KR16-01 (1.Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology, 2.Project Team for Development of New-generation Research Protocol for Submarine Resources, Japan Agency for Marine-Earth Science and Technology, 3.Institute of Industrial Science, The University of Tokyo, 4.Science Research Center, Kochi University, 5.Graduate school of Integrated Arts and Sciences, Kochi University)

Keywords:ferromanganese crust, Takuyo-daigo seamount, MBES, AUV, Urashima

It has been aware of that existence of ferromanganese crusts are closely concerned to microtopographies of seamounts. However, there are insurmountable geographical "scale gap" between bathymetry obtained by ship's multi-beam echo sounder (MBES, ~100m grid data) and observation records of Remotely Operated Vehicle (ROV, description of few meter-scale outcrop). A research cruise YK15-15, Strategic Innovation Program (SIP), New-generation Technology for Ocean Resources Survey (ZIPANG in ocean), "Research on formation process and mechanism of cobalt-rich ferromanganese crusts covering over seamounts in the northwestern Pacific - precise bathymetric survey and seawater sampling by AUV -", was carried out in 2015, to obtain detailed seafloor topography and side scan sonar (SSS) images using Automonous Underwater Vehicle (AUV) "Urashima", for realizing a relationship between distribution of the crusts and microtopographies around southwestern ridge of Takuyo-daigo seamount, where we researched as a typical field of ferromanganese crusts since 2009. Here we report some of the results about detailed topographies and SSS images obtained by AUV "Urashima", comparing with dive logs and photographs obtained by past ROV dives. This project has been implemented as part of “Scientific Research on Genesis of Marine Resources” for “Next-generation Technology for Ocean Resources Exploration,” an initiative that is part of the “Cross-ministerial Strategic Innovation Promotion Program (SIP)” by the Japanese government.