Crustal accretion in the Manila trench accretionary wedge at the transition from subduction to mountain-building in Taiwan
Journal
Earth and Planetary Science Letters
Journal Volume
375
Pages
430-440
Date Issued
2013
Author(s)
Abstract
New marine seismic reflection and coincident wide-angle ocean-bottom seismometer data acquired offshore Taiwan provide high-resolution constraints on the crustal structure of an incipient mountain belt during the earliest stage of arc-continent collision. The new seismic reflection image and travel-time tomography velocity model show evidence for crust of the distal southern Chinese continental margin being subducted eastward beneath the Manila trench and underplated to the accretionary wedge before collision with the southern Chinese continental shelf. The distal margin crust consists of highly extended continental crust interspersed with volcanic bodies and a high-velocity lower crustal layer of likely magmatic intrusions. The distal margin crust is 10-14. km thick outboard of the trench, but thins to 6. km thick beneath the lower slope of the Manila trench accretionary wedge. Along the lower slope of the accretionary prism, we image westward-verging imbricate thrusts and folded strata up to 10. km thick. A sharp decrease in bathymetry marks the transition from lower to upper slope, where we observe a fast (>6.0. km/s) seismic velocity anomaly at the base of the wedge that we interpret as structurally underplated crust from the distal continental margin. Our results support a model of arc-continent collision in Taiwan where the accretionary wedge is first thickened by structural underplating of distal margin crust prior to collision with the continental shelf. The crustal rocks exposed throughout the Central Range in Taiwan may be similarly derived from subducted and structurally underplated crust from the highly extended distal continental margin. © 2013 Elsevier B.V.
Subjects
Arc-continent collision; Manila trench subduction zone; Seismic reflection; Taiwan; Tomography
SDGs
Other Subjects
Arc-continent collision; Continental shelves; Magmatic intrusions; Marine seismic reflections; Seismic reflections; Subduction zones; Taiwan; Travel time tomography; Seismic waves; Tomography; Tectonics; accretion; accretionary prism; arc-continent collision; continental crust; continental margin; continental shelf; crustal deformation; crustal structure; seismic reflection; seismic tomography; seismic velocity; subduction zone; underplating; Manila Trench; Pacific Ocean; South China Sea; Taiwan
Type
journal article