Rifting in the Western Pacific Marginal Seas

The structural features of rifting are reviewed during the formation of Cenozoic basins of the Western Pacific marginal seas. The examples of studied basins confirmed a hypothesis that rifting always starts from a passive phase and is only interrupted by episodes of active rifting. Rifting occurred under NE- and NNE-trending horizontal compression with the formation of either a chain of pull-apart basins or fields of diffuse rifting between the large strike-slip faults (the main part of the South China Sea). The NE and NNE directions of horizontal compression are probably related to the upper mantle convective flows from a spreading ridge of the Indian Ocean, which bear the plate fragments variously deformed during the transportation. The related NNE drift of the Indian, Australian, and Eurasian plates has no link with subduction processes from adjacent Paleopacific plates, which continue to move to northwest. The Western Pacific marginal basins mainly formed without any subduction influence from the Pacific Ocean and can be called backarc basins only based on geographical features.