[M-IS26] Gas hydrates in environmental-resource sciences

[MIS26-05] Biogenic sedimentary structures in a shallow gas hydrate reserve area off Sakata, eastern margin of the Japan Sea

*Koji Seike^1,2, Yuki Ota³, Eri Ikeuchi¹, Masahiro Suzumura³, Hideyoshi Yoshioka¹, Atsushi Suzuki¹ (1.Geological Survey of Japan, AIST, 2.Department of Natural Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 3.nvironmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST))

Keywords:burrow, benthos, seafloor sediments, X-ray CT scanning

The benthic organisms have an important ecological role in the seafloor environments, because they mix sediments, disrupt microstratigraphy, and influence the biogeochemistry of seafloor sediments. Investigating nature of their subsurface activity is essential for further understanding on the seafloor ecosystems, and is also important for assessing anthropogenic impacts such as deep-sea mining. Analyzing biogenic sedimentary structures such as burrows in seafloor sediments can provide useful insights on subsurface ecology of burrowing organisms. We collected sediment core samples from a shallow gas hydrate reserve area off Sakata, eastern margin of the Japan Sea to observe biogenic sedimentary structures of the seafloor sediments. We analyzed the cores with X-ray CT scanning and revealed 3-dimensional burrow structures in the area. In this presentation, we show preliminary results of our ongoing research project on biogenic sedimentary structures under different settings in the gas hydrate reserve area. This study was conducted as a part of the methane hydrate research project funded by METI (Ministry of Economy, Trade and Industry, Japan).