Sub-bottom profiles at massive gas hydrate recovery area between the Umitaka Spur and the Ogi Spur in the Sea of Japan
Massive gas hydrates of biogenic methane were recovered from mound structures at ~20 km northeast to the Umitaka Spur in the Sea of Japan. Mound structures at the Umitaka Spur are associated with thermogenic methane. This is owing to influence of hydrocarbon source rocks at deep sediment depths. These source rocks are widely distributed for the oil and gas fields along the eastern margin of the Sea of Japan. Therefore, the local occurrence of intensive biogenic methane production suggests unique trigger in deep. Investigation of this area and comparison with the Umitaka spur will be useful for understanding complicated nature in deep sediment depths. Sub-bottom profiles (SBPs) were obtained during the 7K18 cruise (September 2018) and the 2K19 cruise (July 2019) by R/V Kaiyo Maru No.7 and R/V Kaiyo Maru No.2 of the Kaiyo Engineering Co., Ltd. (http://kaiyoeng.com/eng/), respectively. A sub bottom profiler (2000DSS of EdgeTech) was towed during the 7K18 cruise and four SBPs (SBP_Site4-A, _Site4-B, _Site5-D, and _Site5-E, respectively) crossing the mound structures were obtained. Position of the towed profiler was obtained by an ultra-short baseline (USBL) acoustic positioning system (cNODE MiniS 34-180 of Kongsberg Maritime) attached to the profiler. SBPs during the 2K19 cruise were obtained using an equipment attached to the ship bottom (TOPAS PS18 of Kongsberg). Two SBPs (SBP_B and _G, respectively) were obtained. Uploaded data Topography map with locations of 6 SBPs SBP (7K18); four SBPs obtained during the 7K18 cruise SBP (2K19); two SBPs obtained during the 2K19 cruise SEG-Y (7K18); four SEG-Y files from the 7K18 cruise SEG-Y (2K19) and SEG-Y (2K19)_2; two SEG-Y files from the 2K19 cruise (note that file format “.seg” in SEG-Y (2K19) was changed to “.sgy” in SEG-Y (2K19)_2) Profiler track (7K18); track of towed sub bottom profiler during the 7K18 cruise Column “J” and “K” of “Original data” are used for “for Generic Mapping Tools”. Profiler track (2K19); track of sub bottom profiler (same with ship track) during the 2K19 cruise Column “I” and “J” of “Original data” are used for “for Generic Mapping Tools”.