The Shuilikeng fault in the central Taiwan mountain belt

For over 200 km along strike the Shuilikeng fault of Taiwan separates Miocene rocks of the Western Foothills from the largely Eocene and Oligocene rocks of the Hsuehshan Range to the east. Despite its importance in the Taiwan mountain belt, the structure and kinematics of the Shuilikeng fault are not well known. Here, we present results from new geological mapping along 100 km of its strike length. At the surface, the Shuilikeng fault is a steeply east-dipping brittle fault with a series of splays and bifurcations. Along its southern part, it cuts an earlier fold and fault system. Outcrop kinematic data vary widely, from thrusting to strike-slip. The surface data are integrated with a relocated and collapsed seismicity database to interpret the fault location at depth. These data indicate that the Shuilikeng fault can be traced to greater than 20 km depth. Some 260 focal mechanisms from this dataset indicate that its kinematics is overall transpressive. From a regional perspective, we interpret the Shuilikeng fault to reactivate a pre-existing rift-related basin-bounding fault to the east of which rocks in the Hsuehshan Range are being exhumed.