The West Philippine Basin, is the oceanic crust located underneath the western part of the Philippine Sea. It was formed during the early Oligocene epoch.[1] To its southwest is the Philippine Trench, and to its east is the Kyushu–Palau Ridge.[2] The West Philippine Basin is deeper and older than the eastern basins and has crustal heat-flow values approaching that of old oceanic crust.[3][4] It is roughly bisected by the Central Basin Fault zone which comprises a band of high relief running from the northwest corner to the Kyushu–Palau Ridge near 14°N. Characterized by the presence of several submarine plateaus (Benham Rise and Anami and Oki-Daito Ridges).
Genesis
editIn terms of origin, two models distinguished:
Trapped oceanic basin
editTrapped basin occurs in two stages: Emplacement of an oceanic basin and Individualization/isolation of the oceanic crust from the rest of the basin. It was invoked by Uyeda and Ben-Avraham (1972); Hilde and others (1977) and Hilde and Lee (1984) and suggests West Philippine Basin as a trapped piece of the Pacific Plate. Envisioned a N-S trending transform fault (connecting two ridges, the Kula Pacific Ridge and the Philippine Ridge/Central Basin Fault as turning into a subduction (the proto-Mariana Trench) zone following a change in the Pacific Plate's motion from NNW to WNW during the Eocene. In this model, the basin is originally a part of the Pacific Plate which was isolated during the kinematic reorganization 43 Ma.
Back-arc basin evolution
editFormed behind a subduction zone and involves process that creates an extensional regime oriented perpendicular to the subduction zone. First proposed by Karig (1971), shows the WPB as forming by back-arc spreading behind the Oki-Daito Ridge starting the Eocene. Crustal extension within the plate took place successively in the eastern portion of the plate to form the other inter-arc basins. Supporters include: Lewis et al. (1982); Seno and Maruyama (1984), Rangin et al. (1990); Hall et al. (1995); Lee and Lawyer (1995), and Deschamps (2002); Honza and Fujioka (2004); Queano et al. (2006).
See also
editReferences
edit- ^ Dennis Brown; Paul D. Ryan (29 June 2011). Arc-Continent Collision. Springer Science & Business Media. p. 433. ISBN 978-3-540-88558-0.
- ^ R. R. Hillis; R. D. Müller (1 January 2003). Evolution and Dynamics of the Australian Plate. Geological Society of America. p. 362. ISBN 978-0-8137-2372-3.
- ^ Watanabe, T., Epp, D., Uyeda, S., Langseth, M., and Yasui, M., 1970. Heat flow in the Philippine Sea: Tectonophysics,v. 10, p. 205–22
- ^ Sclater, J. G., 1972. Heat flow and elevation of the marginal basins of the western Pacific: J. Geophys. Res., v. 77, p. 5705–5719.
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