A NEW APPROACH OF WEDGE DEFORMATION (D-LAYER) - EXAMPLE FROM TAIWAN OROGEN

The interpretation of small-scale orogenic processes, such as the Taiwan orogen, has relied on various wedge deformation theories to analyze mountain-building processes. While these models capture the overall dynamics, they often struggle to accurately represent the complexity of natural processes. To address this, we present a novel D-layer wedge deformation theory that incorporates four key parameters: mechanical property transitions from shallow to deep crust, lithology-dependent hillslope diffusion (erosion and sedimentation), complex wedge basement geometry, and a vertical backstop. This new theory successfully reproduces intricate structures, thermochronology dates, metamorphic temperatures, cooling and exhumation rates, and strain conditions observed in the northern Taiwan orogenic belt. Notably, the theory reveals that ductile deformation accounts for nearly half of the shortening and provides an explanation for the recently detected out-of-sequence fault in Taiwan's orogenic belt. The remarkable consistency between the model result and geological observations suggests that D-layer applicability to other similar wedge orogenic systems.