The Active Detachment of Taiwan: Its Interaction With Large-scale Topography Gives Insight Into Taiwan Wedge Mechanics
Abstract
We imaged active faults in 3D in the Taiwan fold and thrust belt using over 110,000 small earthquakes. The most striking feature is the Main Detachment. It is illuminated by a band of earthquakes that, from sub-horizontal under west-central Taiwan, bends downward and steepens to 30-90 degrees in eastern Taiwan. Other faults abut against it, confirming that it is indeed a through-going feature. The crest of the mountain belt follows the inflection of the Main Detachment in eastern Taiwan, suggesting that the first order topography is controlled by the 3D shape of the detachment. We test this suggestion by an analysis of critical-taper wedge mechanics, which indicates that the topographic reversal is caused by increasing dip of the detachment. Knowing the geometry of the Main Detachment, we could measure directly for the first time the wedge tapers over the entire E-W width of the mountain belt. We concluded that above 15-20 km depth the wedge is at critical taper and shows homogeneous brittle behavior, while below this depth larger tapers indicate that the wedge is undergoing brittle- plastic transition.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27..607C