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Initiation of arc magmatism in an embryonic continental rifting zone of the southernmost part of Okinawa Trough
Author(s) -
Chung S.L.,
Wang S.L.,
Shinjo R.,
Lee C.S.,
Chen C.H.
Publication year - 2000
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.2000.00298.x
Subject(s) - geology , trough (economics) , rift , volcanic rock , magmatism , subduction , back arc basin , volcano , island arc , volcanism , rhyolite , andesite , volcanic arc , paleontology , rift zone , geochemistry , tectonics , seismology , economics , macroeconomics
The Okinawa Trough is a young, intracontinental backarc basin that has formed behind the Ryukyu arc–trench system since late Miocene time. In the Southernmost Part of the Okinawa Trough (SPOT), a cluster of active submarine volcanoes delineates a volcanic belt, which is located only ∼100 km above the Wadati–Benioff zone. We report herein new major and trace element data for the SPOT volcanic rocks. These rocks show a compositional range from medium‐K andesite to rhyolite. Their geochemical characteristics are similar to those of pre‐backarc rifting volcanic rocks from the central Ryukyu arc, and different from those of backarc basin lavas from the Middle Okinawa Trough and the post‐backarc rifting Ryukyu arc volcanics. Therefore, despite being topographically contiguous with the rest of the Trough, the SPOT that developed in the Quaternary is not a simple backarc basin but instead an embryonic rift zone in which early arc volcanism occurs as a result of the Ryukyu subduction.