|
| | Abstract | | We have conducted detailed surface geophysical surveys around the hydrothermal sites off Kumejima island in the Mid-Okinawa Trough. New hydrothermal active area was recently discovered off Kumejima island and the existence of hydrothermal mineral deposits were confirmed by seafloor surveys and rock samplings by ROV. In order to clarify characteristics of magmatic activities and spatial distribution of hydrothermal active area, and further understand the genesis of hydrothermal deposits, the dense magnetic, gravity and bathymetric data were collected during the YK16-10 and YK16-12 cruises aboard the R/V Yokosuka and the KR16-16 cruise aboard the R/V Kairei. The distribution of magnetization and Bouguer gravity anomalies were calculated from the collected magnetic and free-air gravity anomalies and bathymetric data. Finally, we revealed that different types of sub-seafloor magnetic features probably caused by magmatic activities by submarine volcanoes and back-arc rifting and that the hydrothermal site off Kumejima island corresponds to the reduced magnetization zone with the higher gradient part of the Bouguer gravity anomalies. |
|
|
|
| |
|