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| | Abstract | | SMS (Seafloor Massive Sulfide) deposits, including rare and precious metals, have been found in the vicinity of hydrothermal active areas. Geophysical explorations with electromagnetic (EM) methods have been carried out around SMS deposits because SMS deposits are known as low resistivity material. However, resistivity structures below hydrothermal active areas have not been clearly investigated. In this study, we focus on a marine deep-towed DC resistivity survey as an effective tool to the exploration of SMS deposits. The drilling surveys have illustrated the real distributions of SMS deposits are concentrated at narrow (thin) zones. Therefore, we add the Fuzzy C-Means (FCM) clustering constraint into the objective function in the inversion procedure to obtain the sharp-change of resistivity matching given the petrophysical information. The refined inversion results show that the inversion using the FCM clustering constraint can produce the sharp boundaries in resistivity structure, which can incorporate the realistic petrophysical information. We applied the inversion code to the field data obtained at the Okinawa Trough and the inverted resistivity anomalies are consistent with the geological investigations of the hydrothermal fluid flows and the observed distributions of seafloor venting sites. |
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