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No.78 (2004/9) >

Title :Paleostress transition by fault-striation analysis in the northern and central Ryukyu arc, southwest Japan
Authors :Teramae, Noriaki
Hayashi, Daigoro
Authors alternative :林, 大五郎
Issue Date :Sep-2004
Abstract :The Ryukyu arc is an active arc-trench system, associate with active intracontinental back-arc basin (Okinawa Trough). Rifting of the Okinawa Trough has occurred since Miocene. The Ryukyu arc is expected to undergo complex geological history. Paleostress fields of the central and northern Ryukyu island are estimated from fault analysis by use of the Multi-inverse method (Yamaji, 2000) and Ginkgo method (Yamaji, 2003a). The stress transition since middle Miocene is found by measurement of the fault-slip data in the northern and central Ryukyu arc. The fault-striation analysis leads the following tectonic evolution in the central and northern Ryukyu arc. In middle Miocene, E-W extension occurred in the northern Ryukyu arc, which may be related to the opening of the Japan Sea. The compressional stress field occurred in late Miocene to early Pliocene (5-8 Ma), which was simultaneous with the formation of the Taiwan-Shinji Fold Belt. Subsequently E-W extension occurred in Pliocene, which was related to the opening the Okinawa Trough. Around at 2 Ma, complex stress regime occurred in the Ryukyu arc. In this time, opening of the Okinawa Trough resumed and the deposition of the Ryukyu group started. In northern Ryukyu arc, strike-slip stress regime has occurred from 2 Ma ago. NE-SW extension, arc-parallel extension is the latest stress regime in the central and northern Ryukyu arc. Arc parallel extension is observed in the whole Ryukyu arc. On the other hand, before the deposition of the Ryukyu group, stress regime of the southern Ryukyu arc is different from the central and northern Ryukyu arc.
Type Local :紀要論文
ISSN :02869-640
Publisher :琉球大学理学部
URI :http://hdl.handle.net/20.500.12000/2614
Citation :琉球大学理学部紀要 = Bulletin of the College of Science. University of the Ryukyus no.78 p.163 -231
Appears in Collections:No.78 (2004/9)

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