Wu F.T.Jenkins D.M.Mechie J.Roecker S.W.Wang C.-Y.Huang B.-S.HAO KUO-CHEN2022-06-302022-06-30201200948276https://www.scopus.com/inward/record.uri?eid=2-s2.0-84869990281&doi=10.1029%2f2012GL053649&partnerID=40&md5=f54349932d52d3e8918b40edcd5b4d9fhttps://scholars.lib.ntu.edu.tw/handle/123456789/614595Knowledge of the rock types and pressure-temperature conditions at crustal depths in an active orogeny is key to understanding the mechanism of mountain building and its associated modern deformation, erosion and earthquakes. Seismic-wave velocities by themselves generally do not have the sensitivity to discriminate one rock type from another or to decipher the P-T conditions at which they exist. But laboratory-measured ratios of velocities of P to S waves (Vp/Vs) have been shown to be effective. Results of 3-D Vp and Vp/Vs tomographic imaging based on dense seismic arrays in the highly seismic environment of Taiwan provides the first detailed Vp/Vs structures of the orogen. The sharp reduction in the observed Vp/Vs ratio in the felsic core of the mountain belts implies that the-quartz transition temperature is reached at a mean depth of 24 3 km. The transition temperature is estimated to be 750 25C at this depth, yielding an average thermal gradient of 30 3C/km. © 2012. American Geophysical Union. All Rights Reserved.Temperature; Tomography; Crustal depth; Mountain belts; Mountain building; Pressure-temperature conditions; Quartz transition; Rock types; S-waves; Seismic arrays; Seismic evidence; Tomographic imaging; Seismology; crustal structure; erosion; felsic rock; mountain environment; orogeny; P-T conditions; quartz; seismic tomography; seismic wave; temperature gradient; wave velocity; Taiwan[SDGs]SDG10journal article10.1029/2012GL0536492-s2.0-84869990281