Mountain Building in Taiwan: Insights From 3‐D Geodynamic Models

Abstract

Taiwan is widely considered to be a typical example of an arc‐continent collision surrounded by two opposite dipping subduction zones. The manner by which the interaction of the two neighboring slabs caused plate collision and mountain building is insufficiently understood. Various hypotheses have been proposed, but the geodynamic feasibility of those remains to be tested. Here we present 3‐D thermomechanical models to study the geodynamic evolution process of a Taiwan‐like setting after an initial transform fault was consumed. In our model setup, the boundary between the Eurasian plate and the South China Sea is northeast trending. The results show that all simulations result in toroidal mantle flow around the slab edges and that slab breakoff as well as a small‐scale mountain belt with high topography and crustal exhumation occurs in most cases. The Eurasian continental crust is exhumed in a dome‐like manner exposing higher‐grade metamorphic rocks, facilitated by high erosion rates and a weak continental lower crust rheology, but inhibited by the presence of a weak arc. A high topography within the orogen, as well as continental slab detachment, can develop for the convergence direction of N307° and large convergence rates. Our modeling results are thus generally consistent with the Eurasian slab‐tearing model proposed for Taiwan based on seismic tomographic studies, and we suggest that the main characteristic features in Taiwan can be explained by the combined effects of fast erosion, a weak lower crust, fast convergence, and a small convergence azimuth.

P‐wave Tomography and Azimuthal Anisotropy of the Manila‐Taiwan‐Southern Ryukyu Region

“…The present results generally coincide with previous findings, including isotropic tomography (e.g., Ai et al., 2019; Fan et al., 2016, 2015; T. Y. Huang et al., 2012; H. Huang et al., 2014; Koulakov et al., 2015, 2014; Kuo‐Chen et al., 2012; Toyokuni et al., 2016; Ustaszewski et al., 2012; Z. Wang et al., 2006; Zheng et al., 2013), seismic anisotropy (e.g., Fan & Zhao, 2019; B. S. Huang et al., 2006; T. Y. Huang et al., 2015; Koulakov et al., 2015; Kuo et al., 2018; Kuo‐Chen et al., 2009), and 3‐D thermomechanical modeling (e.g., X. X. Wang et al., 2019).…”

Mantle Flow Patterns Beneath the Junction of Multiple Subduction Systems Between the Pacific and Tethys Domains, SE Asia: Constraints From SKS‐Wave Splitting Measurements

“…In addition, the northeastern, eastern, and southern edges of the Celebes Sea are bordered with several subduction zones, including the Cotabato and North Sulawesi subduction zones and the double‐sided subduction of the Molucca Sea plate (Figure 1). Numerical simulations have suggested that dynamic interactions take place in an active, complex tectonic setting composed of multiple subducting slabs (e.g., Király et al., 2016, 2018; Lyu et al., 2019; X. Wang et al., 2019). The upper mantle around the Celebes Sea is also proposed to have experienced a complex deformation history due to the subduction of multiple slabs in adjacent subduction zones (e.g., Di Leo et al., 2012a, 2012b; Király et al., 2018; Roy et al., 2017).…”

3D Geodynamic Models for HP‐UHP Rock Exhumation in Opposite‐Dip Double Subduction‐Collision Systems

“…Moreover, the simulated peak temperatures and pressure are determined to be 300°C and 0.5 GPa in the Backbone Range, 230°C and 0.32 GPa in the Hsuehshan Range, and 140°C and Lee et al (2015) shown and in Figure 9b2 computed from Fuller et al (2006). Temperature-time paths for tracers of (c1) profiles AA′ and BB′ in this study and (c2) profiles AA″ and BB″ in Wang et al (2019). The locations of the four profiles and the dashed lines are shown in Figure 9b.…”

“…The horizontal distance between the plate edges, which is represented by Dp at 70 km in all of the initial 3D double subduction-collision model setups, is sufficiently low to cause strong slab-slab interactions (Holt & Royden, 2020;Király et al, 2016Király et al, , 2021Peral et al, 2018;Wang et al, 2019). These interactions lead to different crustal deformation behaviors in the initial transform-fault region (Figures 3, 4, 6 and 7d).…”