Fig. 29
Generalized maps, cross sections, and strain states for the Tailuko and Yuli Belts as they are accreted/subducted and extruded. A ~6.0–3.0 Ma, accretion of Tailuko and Slate Belts and subduction of Yuli Belt as continental crust of Eurasia enters the Luzon subduction zone. Kinematics and strain partitioning along the plate boundary are from Ho et al. (2022). Schematic cross section X–X’ at the time shown in A. B ~3.0–0.7 Ma, vertical and westward extrusion of the Yuli Belt accommodated by reactivation of the Tailuko strike-slip shear zone as a high-angle reverse fault, the Shoufeng shear zone (SSZ). Westward extrusion accelerates slip on the Chaochou Fault (CF in cross section) and offsets the left-lateral shear zone in the Tailuko Belt, creating a left-stepping releasing bend. Geochronologic data suggests northeast stretching (black arrows) started ca. 2.4 Ma (this study). The location of reconstructed units relative to Taiwan is for general reference. C General strain states for three deformation stages with “S” representing the stretch (S = 1 + elongation) for each of the principal strains with S1 > S2 > S3. D2: strike-slip deformation in the Tailuko Belt during oblique convergence and strain partitioning (Ho et al. 2022). D3: east-dipping high-reverse fault between Tailuko and Yuli Belts (represented by red dashed and continuous lines). Orientations and relative magnitude of stretches are poorly known, but maximum stretch S1 is assumed to be nearly vertical. D4: vertical thinning and extrusion of the Yuli Belt that minimizes the vertical stretch while the releasing bend during oblique convergence maximizes the horizontal stretch. Black dashed line represents late-stage foliation. Note that the maximum stretch trends northeast for D2 and D4