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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS014 Poster presentation 2313
Numerical simulation of the transition from subduction to arc-continent
collision in offshore southeastern Taiwan
Prof. Wei-Hau Wang
Institute of Applied Geophysics National Chung Cheng University, Taiwan IASPEI
Hwong-Yi Wu
We conducted 2D finite element modeling to simulate the forearc structures adjacent to the Lutao-
Babuyan ridge in between the Philippines and Taiwan, where the North Luzon Trough, a typical forearc
basin near the Philippines, gradually breaks down into two small basins around the offshore of
southeastern Taiwan as the collision between the Luzon arc and the Eurasian plate initiates. Our
simulation results suggest that the strength contrast between the accretionary wedge and the Luzon arc
is the most important factor controlling regional tectonic style. Northwest of Luzon, the soft sediments
in front of competent volcanic arc lead to a large strength contrast and result in a single forearc basin.
As the Luzon arc moves closer to the Taiwan Island, the Taiwan orogeny would make the accretionary
wedge uplift and lithified. Once the lithified accretionary wedge becomes 10 times stronger than the
sediments deposited in the forearc basin, our model suggests that the lithified accretionary wedge
would act as a new backstop that deforms the sediments in the forearc basin. As a result, a new ridge
forms within the former forearc basin and divides it into two small basins. Our simulation results also
suggest that the transition from unlithified to lithified accretionary wedge would lead to a stress change
from the thrust type to strike-slip type, which is consistent with regional structures.
Keywords: forearc, lutao babuyan, taiwan