探査工学部門委員会，陸海資源探査委員会合同企画セッション「陸から海にいたる探査技術とビッグデータ処理技術」（Division of Exploration Technology / Research and investigation committee on resource exploration from land to ocean to develop fundamental and big data processing techniques）

[3101-06-05] Integration of spatial models of resistivity and chemical concentration data by drillings for metal-grade imaging of a seafloor hydrothermal vent area

○Ribeiro de Sá Vitor¹、小池 克明¹、後藤 忠徳¹、鈴木 勝彦² (1. 京都大学、2. 海洋研究開発機構)

司会：木崎彰久（秋田大学）
Chairman: Akihisa Kizaki (Akita university)

キーワード：地球統計学、海底熱水噴出域、比抵抗検層データ、元素濃度、沖縄トラフ

Seafloor hydrothermal vent areas have been important exploration target as a source of volcanogenic massive sulphide (VMS) type deposit. As compared to land areas, geological information usually obtained by drilling surveys and well logging is quite limited in seafloor in both the amount and location. Therefore, spatial modeling of metal grade is difficult to be archived with adequate accuracy. For this problem, this study aims to enable such modeling by geostatistical analyses of resistivity and chemical concentration data by drillings in a seafloor hydrothermal vent area by selecting the Iheya North Knoll, situated 150 km NW of Okinawa Island, as a case study. This area is in the middle Okinawa Trough, a back-arc basin under an extensional stress field. Turning band, a geostatistical simulation method, is used to clarify the 3D resistivity distribution and then, the distribution is combined with the metal concentrations for producing a preliminary metal-grade model. As the result, high grade zones of layered shape are estimated at certain depths and their formation is considered to be controlled by hydrothermal fluid flows and mixing with sea water.