Structural Analysis of Bending Fold and Sub-Horizontal Foliation in the Eastern Central Range of Taiwan and Its Tectonic Implications

Rapid exhumation of the youngest blueschist-facies rock is reported along the Yuli belt of the eastern Central Range, Taiwan. Structures and strain distribution associated with blueschist facies exhumation is essential to understanding the structural history and kinematic evolution of Taiwan mountain belt. A km-scale bending antiform cropped out in the eastern slate belt, SE Taiwan. Normal shear parasitic folds, associated sub-horizontal crenulation cleavages (S3) and normal faults with quartz vein are observed in both limbs of bending antiform, which yield conflicting interpretation with buckling folds in Taiwan mountain belt. Both results of 3D MT inversion and temperature distribution also gave the antiform explanation. These results might suggest that a doming structure is growing. 1D shortening analyses of S3-related folds among Tailuko, Yuli and eastern slate belts illustrate that Yuli belt has the most shortening perpendicular to S3 cleavage and Tailuko belt has the highest ratio of simple shear over pure shear. These structure observations and strain distribution pattern must be taken into consideration for the exhumation processes of Taiwan mountain belt.