[S-CG48] Ocean Floor Geoscience

[SCG48-P24] An attempt to collect long sediment samples by modifying a multiple corer

*Katsura Kameo¹, Makoto Takeuchi¹, Masanari Ashida¹, Junichiro Kuroda¹, Juichiro Ashi¹, Taisei Hatano², RYO NAKANISHI³, Masafumi MURAYAMA⁴ (1.Atomosphere and Ocean Research Institute, The Unviersity of Tokyo, 2.Graduate School of Integrated Arts and Sciences,Kochi University, 3.Graduate School of Science,Kyoto University, 4.Faculty of Agriculture and Marine Science,Kochi University)

Keywords:Multiple corer, modification, longer sediment core, bottom surface sediment

The multiple corer is one of an essential observation tool for biology, geochemistry, and geology as it allows for undisturbed sampling of surface sediments around the seafloor (e.g., Ikahara, 1993). Currently, it utilizes a 60 cm-long coring tube to collect approximately 30 cm of surface sediment, but there is a growing demand for collecting longer sediment cores. Therefore, modifications have been made to the multiple corer (Rigosha Co., Ltd.) operated at the Atmosphere and Ocean Research Institute, The University of Tokyo, by attaching extended coring tubes (100 cm or 140 cm in length) to enable sampling of longer sediment cores. Modifications have been made to the arm length, spring strength, and additional weight of the corer, and repeated tests have been conducted during several research cruises to successfully collect surface sediments exceeding 60 cm in length. Particularly, a self-recording deep-sea camera has been mounted on the multiple corer frame to confirm the operation of the corer and sediment sampling conditions on the seafloor.
In the northwestern Pacific region (at a depth of about 6000 m), sediment samples were collected, with a 60 cm-long corer tube retrieving sediment from only the oxidized layer and a 100 cm-long corer tube retrieving sediment from the 60 cm-thick oxidized to reduced layer. Furthermore, off the coast of Kuji (at a depth of 4200 m), the sampling conditions of surface sediments were compared using three types of corers: the multiple corer, gravity corer and piston corer. This report presents the results of these comparisons and the conditions of the surface sediments.

Reference
Ikehara, K. (1993) Multiple corer, a sampler for taking undisturbed surface sediments; for study on interaction between water and sediments. Journal of the Sedimentological Society of Japan, 39, 85-89.