沖縄トラフの発生と形成  [in Japanese] Genesis and formation of the Okinawa Trogh, Japan  [in Japanese]

Recent geologic and geophysical data revealed that the Greater Okinawa Trough consisits of two troughs such as the Old and New Okinawa Troughs. The Old Okinawa Trough had been formed during Late Miocene to Pliocene time as a big graben in the continental margin. And then, the New Okinawa Trough, so-called Okinawa Trough, has been formed since some time in Early Pleistocene time (2-1.5 Ma). The present time is regarded as a continental rifting stage in the Okinawa Trough because of no ocean ic crust detected beneath the Okinawa Trough. There exist central rifts in the Okinawa Trough, which are centers of the magmatic uplifting in both of the Okinawa Trough and the Greater Okinawa Trough. The central rifts are most active in the troughat present. There, discovery of a black smoker was reported at one of active hydrothermal vent systems in 1989. Seismic reflection and submarine drilling data strongly show eastward migration of the big trough-type sedimentary basins during Neogene time.