Mountain-building in Taiwan and the critical wedge model

Recently accumulated geophysical data for Taiwan have provided an opportunity to examine the deep structure and the construction of an active fold-and-thrust mountain belt. Analyses of gravity anomalies and seismic tomography show the occurrence of high-density and high-velocity rocks beneath the Central Ranges extending from near the surface to depths of 40-70 km. Together with surface geology, fission-track data and radiometric data, the results show that large-scaled, autochthonous uplift of basement rocks from depths beneath the Central Ranges may have occurred since the last 1 Ma. These results are in contrast with the model of thin-skinned growth of a critical wedge, that was thought to occur across the entire Taiwan orogen.