Impact of Basement High on the Structure and Kinematics of the Western Taiwan Thrust Wedge:Insights From Sandbox Models

Abstract

Experimental modeling allows description of the development and kinematics of structures in mountain belts formed during oblique convergence. In the collision geometry of the Taiwan mountain belt, the Chinese continental margin is oriented about N60E, whereas the N16E Philippine Sea plate backstop is moving toward the Eurasian plate in a N55W direction. In addition to this oblique convergence mechanism, most of the foreland structures are strongly influenced by the shape of the backstop and structural highs. Sandbox experiments have been conducted to simulate the neotectonics of western Taiwan. The kinematics of deformation comprises a combination of compression and rotation, which results in a local partitioning between thrusting and strike-slip movements. The results of specific analog models demonstrated that: (1) most of the tableland structures in the western Taiwan, such as the Tatu, Pakua, chungchou and Chia-Yi tablelands can be interpreted as a hinge part of drag anticline formed by fault-propagating fold process; (2) most of the basin and plain structures in the western Taiwan, such as Taichung and Chianan basins, can be inter preted as a part of piggy back basins; (3) the frontal thrust may have the first appearance of rupture in front of and between the Peikang high and the Kuanyin high; (4) NW trending link faults may be developing within the transfer aones; and (5) an escape structure formed to the south of the Peikang high can be correlated with bathymetric map and models.

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