East Asia plate tectonics since 15 Ma: constraints from the Taiwan region
Resource
Tectonophysics 344 (1-2): 103-134
Journal
Tectonophysics
Journal Volume
344
Journal Issue
1-2.
Pages
103-134
Date Issued
2002
Date
2002
Author(s)
Sibuet, Jean-Claude
Hsu, Shu-Kun
Pichon, Xavier Le
Formal, Jean-Pierre Le
Reed, Donald
Moore, Greg
Abstract
15 Ma ago, a major plate reorganization occurred in East Asia. Seafloor spreading ceased in the South China Sea, Japan Sea, Taiwan Sea, Sulu Sea, and Shikoku and Parece Vela basins. Simultaneously, shear motions also ceased along the Taiwan-Sinzi zone, the Gagua ridge and the Luzon-Ryukyu transform plate boundary. The complex system of thirteen plates suddenly evolved in a simple three-plate system (EU, PH and PA). Beneath the Manila accretionary prism and in the Huatung basin, we have determined magnetic lineation patterns as well as spreading rates deduced from the identification of magnetic lineations. These two patterns are rotated by 15°. They were formed by seafloor spreading before 15 Ma and belonged to the same ocean named the Taiwan Sea. Half-spreading rate in the Taiwan Sea was 2 cm/year from chron 23 to 20 (51 to 43 Ma) and 1 cm/year from chron 20 (43 Ma) to 5b (15 Ma). Five-plate kinematic reconstructions spanning from 15 Ma to Present show implications concerning the geodynamic evolution of East Asia. Amongst them, the 1000-km-long linear Gagua ridge was a major plate boundary which accommodated the northwestward shear motion of the PH Sea plate; the formation of Taiwan was driven by two simple lithospheric motions: (i) the subduction of the PH Sea plate beneath Eurasia with a relative westward motion of the western end (A) of the Ryukyu subduction zone; (ii) the subduction of Eurasia beneath the Philippine Sea plate with a relative southwestward motion of the northern end (B) of the Manila subduction zone. The Luzon arc only formed south of B. The collision of the Luzon are with Eurasia occured between A and B. East of A, the Luzon arc probably accreted against the Ryukyu forearc. © 2002 Elsevier Science B.V. All rights reserved.
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