Thermomechanical models of Taiwan’s orogeny with along-strike variability

Taiwan is situated within an active arc–continent collision zone and represents one of the most rapidly exhuming orogens on Earth, characterized by complex structural architecture. In our previous work, we developed a comprehensive thermomechanical model that incorporates the depth-dependent transition from brittle to ductile deformation, lithology-controlled erosion, and observed geometries of the basal decollement and backstop. The model successfully reproduces the key structural features of the northern Taiwan orogen and is consistent with metamorphic temperature profiles, thermochronological constraints, spatial patterns of strain, and the observed rates of exhumation and cooling. The results further demonstrate the critical roles of ductile deformation and ramp structures in the formation of the Hsuehshan Range and the Western fold-and-thrust belt.

Structural styles, however, vary systematically from north to south across the Taiwan orogen. Notably, the Hsuehshan Range is absent in southern Taiwan, and total crustal shortening decreases significantly toward the southern tip of the island.

Here, we apply the same thermomechanical framework under varying boundary conditions to reconstruct the along-strike evolution of mountain building across Taiwan.

Our results indicate that the timing of orogenic onset is comparable along strike, whereas the rate of shortening decreases progressively from north to south. The basal decollement extends to approximately 20 km depth and exhibits variable ramp–flat geometries, leading to distinct structural styles along the orogen. The model successfully captures the development of the Pingtung Basin and the structural evolution of the Hengchun Peninsula, providing a unified framework for understanding the along-strike variability of Taiwan’s orogeny.