The obliquity of the arc-continent collision in Taiwan is thought to have produced a southward- propagating orogenic system starting as early as 8 Ma. We combine 62 new zircon fission- track ages with timing of rapid subsidence in the foreland basin to identify the timing of the onset of exhumation and orogenesis. The oldest completely reset zircon fission-track ages and the onset of rapid tectonic subsidence in both the northern and southern parts of the foreland basin are ca. 5-6 Ma. We propose that north-south rifting in the South China Sea created a north-trending continental margin before the collision rather than the commonly assumed northeast-trending margin. Consequently, both this north-trending continental margin and the Luzon arc of the Philippine Sea plate were subparallel, resulting in an initial collision that was simultaneous along strike.
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