Simultaneous mountain building in the Taiwan orogenic belt
Tuesday, 16 December 2014: 4:00 PM
The Taiwan orogenic belt results from a collision between the Luzon Arc and Eurasia Plate. Since the pioneering work of Suppe (1984), many researches have considered the collision to be a result of an oblique collision between the N-S trending Luzon Arc, which moves NW at 8-9 cm/yr., and the NE trending continental margin of the EurasiaPlate. This collision is thought to have produced a southward propagating orogenic system. We combine zircon fission-track ages along the Hsüehshan and Central Ranges with timing of rapid subsidence in the foreland basin to identify the timing of the onset of orogenesis. The oldest completely reset zircon fission-track ages are ca.5 Ma along nearly the entire length of the orogen and the onset of rapid tectonic subsidence in both the northern and southern parts of the foreland basin is also ca. 5Ma. We propose that N-S rifting in the South China Sea created a N-S trending continental margin before the collision rather than the commonly assumed northeast trending margin. Consequently, both this N-S trending continental margin and the Luzon arc of the Philippine Sea Plate were sub-parallel, resulting in a simultaneous collision.