How Was The West Philippine Basin Created ?
Ching-Ming Chang
Abstract
These three articles are all primary based on the bathymetry data in west Philippine Basin which acquired from multibeam system.
West of the Central Basin Spreading Center (CBSC), ．．fast-spreading・・ features (overlapping spreading centers, volcanic axial ridges, and smooth abyssal hill fabric) are identified. In contrast, ．．Slow-spreading features・・ (deep rift valleys and nodal basins, rough abyssal hills on the ridge flanks, and mantle Bouguer anomaly lows beneath segment centers) are observed in the eastern CBSC.
Based on geological and geophysical data in WPB and its boundaries, the authors` model shows that it is a back arc basin that developed between two opposed subduction zones. Rifting started around 55 Ma and spreading ended at 33/30 Ma. The Gagua and Palau-Kyushu ridges acted as transform margins accommodating the opening. Then shortly after the end of the spreading, a late stage of amagmatic extension occurred between about 30 and 26 Ma in the central part of the basin, being responsible for the deep rift valley that cut across the older spreading fabric.
Reference
A. Deschamps, S. Lallemand, The West Philippine Basin,an Eocene to Early Oligocene back-arc basin opened betweentwo opposed subduction zones, J. Geophys. Res.,submitted.
A. Deschamps, S.E. Lallemand, S. Dominguez, The last spreading episode of the West Philippine Basin revisited,Geophys. Res. Lett. 26 (1999) 2073^2076.
Okino, K., and K. Fujioka, The Central Basin Spreading Center in the Philippine Sea: Structure of an extinct spreading center and implications for marginal basin formation, J. Geophys. Res., 108(B1), 2040, doi:10.1029/2001JB001095, 2003.