Seismic Stratigraphy and Structural Characteristics of Seafloor Hydrothermal Site in the Mid-Okinawa Trough
Abstract
In recent years, integrated survey for marine mineral resources have been conducted. As a part of these surveys, we carried out several high resolution seismic surveys to seafloor hydrothermal sites in the Mid-Okinawa Trough. We obtained high resolution cross-sections of the seafloor hydrothermal site that enabled us to identified structural characteristics from the viewpoint of seismic facies. We identified the stratified area and cracking area within the upper seafloor hydrothermal site. Hydrothermal vent sites within the chimney walls evolve, located on the cracking area, which supports the view that cracking area may provide pathways for hydrothermal fluids. In addition, we identified the low amplitude area below the vent site. These low amplitude areas indicate a lack of acoustic impedance contrast over these sections, suggesting that changing of host rock physical properties may have occurred caused by hydrothermal alteration below the vent site. In the velocity analysis, we identified high velocity anomalies above the negative-polarity reflector. As a result of comparing the information of the drilling core, the lower surface of the massive sulfide ore and the negative-polarity reflections matched well. It is suggested that these high velocity anomalies are coursed by distribution of massive sulfide deposits. These seismic stratigraphy and structural characteristics were identified in areas where seafloor hydrothermal deposits are distributed in the Mid-Okinawa Trough. From these results, it is estimated that the hydrothermal deposits in the Mid-Okinawa Trough have undergone similar formation history.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V33A..02T
- Keywords:
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- 0930 Oceanic structures;
- EXPLORATION GEOPHYSICSDE: 1034 Hydrothermal systems;
- GEOCHEMISTRYDE: 3616 Hydrothermal systems;
- MINERALOGY AND PETROLOGYDE: 8424 Hydrothermal systems;
- VOLCANOLOGY