Characteristics of Electrical and Gravitational Fields in the Hydrothermal Ore Deposit Areas in the Mid-Okinawa Trough
Abstract
The electrical prospecting by a deep-tow and the ocean bottom gravity survey by a ROV were carried out in both the Izena Hole and the west off Kumejima where the hydrothermal ore deposits exist in the Mid-Okinawa Trough. In the electric survey, clear Self-Potential (SP) anomalies were observed, and the results that the areas showing the negative SP anomalies were lower resistivity than the seawater were obtained at the same time. According to Kawada and Kasaya(2017), such negative SP anomalies are interpreted as being due to the "Geo-battery" formed by ore bodies beneath the seafloor. These negative SP anomalies and low resistivity areas correspond to the hydrothermal deposit area in the Izena Hole, and further in the west off Kumejima, the existence of the sulfide layers were confirmed by surveys using the Benthic Multi-coring System (BMS). From these results, it was confirmed that this exploration method is extremely effective in narrowing down the hydrothermal deposit area. Subsequently, the ocean bottom gravity survey was also conducted on two lines in the west off Kumejima. As a result, high gravity anomalies were observed around the point where the sulfide layer was the thickest, which indicates that the high density materials are buried. This is considered to indicate the scale of the sulfide deposit.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V43F0171K
- Keywords:
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- 0930 Oceanic structures;
- EXPLORATION GEOPHYSICSDE: 1034 Hydrothermal systems;
- GEOCHEMISTRYDE: 3616 Hydrothermal systems;
- MINERALOGY AND PETROLOGYDE: 8424 Hydrothermal systems;
- VOLCANOLOGY