摘要： The convergence of the Philippine Sea and the Eurasian plates in the Taiwan region led to the formation of a young collisional mountain between two subduction zones of nearly orthogonal polarities. The geological processes underlying the collision and its relation to subduction are the primary targets of TAIGER (Taiwan Integrated Geodynamic Research) project. Newly acquired passive and active sources data on land, supplemented by ocean bottom as well as permanent seismic network data, are used to derive a new 3‐D tomographic velocity model. Using the 7.5 km/sec contour as a marker for crustal deformation, two trend‐parallel “roots,” one under the Central Range with a maximum depth of 55 km and the other under the Coastal Range at 40 km, are found to extend from southern to central (∼24°N) Taiwan. Between the two roots and lying approximately beneath the Longitudinal Valley, the 7.5 km/sec contour rises to 25 km depth. In the upper mantle, a high velocity zone, east‐dipping and its upper surface coinciding with a Wadati‐Benioff zone in the south (∼22.8°N), becomes near vertical and ill‐defined in the north (∼23.9°N). The crustal deformation as defined by the “roots” and the along‐trend variations of the upper mantle structures under Taiwan provide key information for the orogeny. With the thickening of crust to 55 km or more processes such as eclogitization and delamination may come into play. 其他題名： J. Geophys. Res 出版者： Washington, DC: Blackwell Publishing Ltd 出版日期： 2012-06 出處： Journal of Geophysical Research Atmospheres, 2012-06, Vol.117 (B6), p.B06306--n/a 資源來源： Wiley Online Library All Journals 版權： Copyright 2012 by the American Geophysical Union 版權： 2015 INIST-CNRS 識別號： ISSN: 0148-0227 識別號： ISSN: 2169-9313 識別號： ISSN: 2156-2202 識別號： EISSN: 2156-2202 識別號： EISSN: 2169-9356 識別號： DOI: 10.1029/2011JB009108
