| 講演要旨(和文) | | 本研究では，発達中の海底熱水鉱床の電気物性を解明することを目的に，2016年2月から3月にかけて行われた沖縄県沖での掘削航海”ちきゅうCK16-01航海” (戦略的イノベーション創造プログラム"次世代海洋資源調査技術"の枠組みの下実施) において掘削試料の比抵抗・IP特性計測を行った．その結果，堆積層の比抵抗は，多孔質なマトリックスを満たす低比抵抗の海水により本質的に規制されていることが分かった．また，IP特性に関しては，硫化鉱物を含む堆積層で比較的大きな位相差が生じることが分かった．局所的に，400mradを超える位相差が計測された箇所も存在した．位相差が最大値を取る時の交流周波数は試料により異なり，硫化鉱物の粒径の違いを反映している可能性が示唆された．これらのことから，海底下で発達中の熱水鉱床においてもIP効果が有効である可能性が示された． |
|
|
| | 講演要旨(英文) | | The present study investigated the electrical properties of the drillcore samples from the seafloor hydrothermal system in Okinawa, Japan, under the program of Cross-ministerial Strategic Innovation Promotion Program (SIP). Particularly, their features about resistivity and Induced Polarization (IP) were successfully measured. Resistivity features showed that the resistivity is essentially controlled by the connectivity of pore fluids, compared with the results of porosity measurements. A discrepancy between the resistivities measured in this study and those from Logging While Drilling (LWD) suggested that the resistivity is also affected by high temperature condition provided by the hydrothermal activity of the system. Relatively strong signals of the IP effect were obtained from the samples containing a large amount of sulfides. Differences of the peak frequency between the samples could be due to the grain size of the sulfides. |
|
|
|
| |
|