Propagators and ridge jumps in a back‐arc basin,the West Philippine Basin |
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| Authors: | Anne Deschamps Ryuichi Shinjo Takeshi Matsumoto Chao‐Shing Lee Serge E Lallemand Shiguo Wu Scientific party of KR‐ and KR‐ cruises |
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| Institution: | 1. Université Européenne de Bretagne, Université de Brest/CNRS, UMR 6538 Domaines Océaniques, IUEM, Place N. Copernic, 29280 Plouzané, France;2. Department of Physics and Earth Sciences, University of the Ryukyus, Senbaru‐1, Okinawa 903‐02313, Japan;3. Institute of Applied Geophysics, National Taiwan Ocean University, 2 Pei‐Ning Road, Keelung 202, Taiwan;4. Géosciences Montpellier, Université Montpellier 2, CC.60, Place E Bataillon 34095 Montpellier Cedex 05, France;5. Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China;6. KR03‐04 and KR04‐14 Cruises Scientific Party: M. Shirahashi (Univ. Ryukyus: UR), S. Inoue (UR), Y. Maeda (UR), R. Matsumura (UR), M. Miyamoto (UR), H‐M. Kao (National Taiwan Ocean Univ.: NTOU), J. Lee (NTOU), C‐H. Tsai (NTOU)), T. No (Nippon Marine Enterprises, Ltd.: NME), S. Hosoya (NME), H. Shibata (NME), T. Kodera (NME), Y. Sato (Marine Works Japan, Ltd.: MWJ), Y. Sagawa (MWJ), O. Cabrera (Dept Foreign Affairs, Maritime and Ocean Affairs Center, Philippines) |
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| Abstract: | We explore the tectono‐magmatic processes in the western West Philippine Basin, Philippine Sea Plate, using bathymetric data acquired in 2003 and 2004. The northwestern part of the basin formed through a series of northwestward propagating rifts. We identify at least five sequences of propagating rifts, probably triggered by mantle flow away from the mantle thermal anomaly that is responsible for the origin of the Benham and Urdenata plateaus. Gravitational forces caused by along‐axis topographic gradient and a ～30° ridge reorientation appear to also be driving the rift propagations. The along‐axis mantle flow appears to be reduced and deflected along the Luzon‐Okinawa fracture zone, because the spreading system remained stable west of this major fault zone. North‐east of the Benham plateau, a left‐lateral fracture zone has turned into a NE–SW‐trending spreading axis. As a result, a microplate developed at the triple junction. |
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