Embryonic rifting zone revealed by a high-density survey on the southern
margin of the southern Okinawa Trough
- Ayanori Misawa
, - Masahiko Sato,
- Seishiro Furuyama,
- Jih-Hsin Chang,
- Takahiko Inoue,
- Kohsaku Arai
Seishiro Furuyama
Department of Marine Resources and Energy, Tokyo University of Marine Science and Technology
Author ProfileJih-Hsin Chang
Geological Survey of Japan, the National Institute of Advanced Industrial Science and Technology (AIST)
Author ProfileTakahiko Inoue
Geological Survey of Japan, the National Institute of Advanced Industrial Science and Technology (AIST)
Author ProfileKohsaku Arai
National Institute of Advanced Industrial Science and Technology
Author ProfileAbstract
Offshore northern Ishigaki-Jima Island, in the southern Okinawa Trough,
offers outstanding opportunities to explore the rifting stage of a
backarc system. We report the results of integrated marine geological
and geophysical surveys with high-density survey lines in this area. We
identify a graben bounded by normal faults and extending approximately
59 km in an ENE-WSW direction off-axis of the southern Okinawa Trough.
Submarine volcanoes with active hydrothermalism and associated intrusive
structures lie in the graben. Magnetic anomaly and seismicity data in
and around the graben suggest the presence of relatively shallow magma
acting as a heat source. All features identified in and around the
graben suggest active rifting in the southern Okinawa Trough.
