Natural gamma ray logging at sea-floor hydrothermal deposit in Izena Hole off-shore Okinawa

Yoshinori Sanada, Yasuhiro Yamada, Kazuya Kitada, Tatsuo Nozaki, Hidenori Kumagai, Jun Ichiro Ishibashi, Lena Maeda

研究成果: 会議への寄与タイプ論文


Natural gamma ray logging was carried out at the five wells in Izena Hole off-shore Okinawa by D/V Chikyu on November to December in 2016. This is one of the research cruise under an umbrella of Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation technology for ocean resources exploration (Zipangu in the Ocean program)". The purpose of this survey is to understand geological profile and distribution of the subsurface hydrothermal deposit. It is difficult to take good quality and recovery cores in hydrothermal brittle formation. On the other hand, the continuous natural gamma ray logging data allows us to describe continuous vertical formation profile. The memory-type logging tool was stuck out just below the drill bit at the bottom of borehole after cutting cores. The tool measures logging data during pulling out of the hole. Natural gamma ray, temperature and pressure were measured in the boreholes. The gamma ray data by logging tool has good correlation with that in the core data by laboratory measurement until ~30-80m below sea floor at the good core recovery intervals. The logging data are only continuous profile below the depth till maximum 180m below sea floor. The gamma ray data indicate classification of sediment layer, ore body, and alternate layer in this region. The temperature logging indicates potential of hydrothermal deposit activity. The pressure data shows static water column.

出版物ステータス出版済み - 1 1 2017
イベント23rd Formation Evaluation Symposium of Japan 2017 - Chiba, 日本
継続期間: 10 11 201710 12 2017


その他23rd Formation Evaluation Symposium of Japan 2017


All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology
  • Geology
  • Energy Engineering and Power Technology
  • Economic Geology
  • Geochemistry and Petrology


Sanada, Y., Yamada, Y., Kitada, K., Nozaki, T., Kumagai, H., Ishibashi, J. I., & Maeda, L. (2017). Natural gamma ray logging at sea-floor hydrothermal deposit in Izena Hole off-shore Okinawa. 論文発表場所 23rd Formation Evaluation Symposium of Japan 2017, Chiba, 日本.