HR: 1330h
AN: T32A-0903    [PDF]
TI: Overlapping Spreading Centers, Ridge Jumps and Ridge/Hotspot Interaction: the Northwestern West Philippine Basin as Study Example
AU: * Deschamps, A
EM: adeschamps@whoi.edu
AF: JAMSTEC, Japan Marine Science & Technology Center, Deep Sea Research Dept., 2-15 Natsushima-cho, Yokosuka-shi, Kanagawa 237-0061, Japan Now at WHOI, Geology & Geophysics Department, 360 Woods Hole Rd., Woods Hole, MA 02543-1542 United States
AU: Shinjo, R
EM: rshinjo@sci.u-ryukyu.ac.jp
AF: Univ. Ryukyus, Department of Physics & Earth Sciences, Senbaru-1, Nishihara, Okinawa, 903-0213 Japan
AU: Lallemand, S
EM: lallem@dstu.univ-montp2.fr
AF: Dynamics of Lithosphere Lab, CC.60, place Bataillon, Montpellier, 34095 France
AB: We conducted a geophysical cruise, including ROV dives, in the northwestern part of the West Philippine Basin (WPB) in April-May of 2003. Our survey indicates that the well-established spreading center (uncorrectly known as the Central Basin Fault) of the WPB is relayed in the northwest by a series of at least seven overlapping spreading centers (OSC) that align against the Luzon-Okinawa Fracture Zone. We observe systematic southward ridge jumps with propagating rifts to the south and failed ones to the north. These OSCs reveal the continuous interaction - and cyclic effects - between a propagating spreading center and the hotspot that has produced the Benham Rise (and its derivative Urdaneta Plateau) during Middle and Late Eocene and what could be the present-day Manus hotspot. Fresh basalts and dolerites were collected using ROV Kaiko at the northernmost margin, northern Urdaneta Plateau, and the failed rifts. We thus expect to get soon chronological constraints on rates of ridge propagation and ridge jumps in relation with the simultaneous northward drift of the growing Philippine Sea plate, in addition to geochemical characteristics of source mantle(s).
UR: http://www.whoi.edu/science/GG/people/adeschamps/
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 3045 Seafloor morphology and bottom photography
DE: 3640 Igneous petrology
DE: 8122 Dynamics, gravity and tectonics
DE: 8150 Plate boundary--general (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting