Using an autonomous underwater vehicle (AUV) equipped with a three-axis electric field receiver we were able to make measurements of self potential (SP) fields over a hydrothermal prospect in the Iheya area of the Okinawa Trough, southwest of Japan. Additionally, by deploying battery-powered controlledsource EM (CSEM) transmitters on the seafloor, we were able to make CSEM measurements out to ranges of about 800 m. We observed negative SP anomalies associated with seafloor mounds, localized close to the seafloor and probably associated with hydrothermal venting. Apparent conductivities computed from the CSEM data were as high as 30 S/m, and were not correlated with the largest SP anomalies. A preliminary 3D inversion yielded a compact, 10 S/m body extending 100 m below the seafloor. The high conductivities may be associated with hydrothermal systems, but more likely are a manifestation of submarine massive sulfide (SMS) deposits.
Presentation Date: Thursday, October 18, 2018
Start Time: 8:30:00 AM
Location: 213A (Anaheim Convention Center)
Presentation Type: Oral
