The orientation of stretching associated with development of the pervasive foliation in Taiwan varies from west to east across the Taiwan mountain belt from down-dip to along-strike. This variation in the stretching direction was developed during the ongoing collision and affected both basement rocks and Tertiary cover. Analyses of incremental and finite strain in Eocene slates of the eastern Central Range of Taiwan indicate finite extension parallel to a shallowly plunging strike-parallel lineation. Pyrite pressure shadows depict complicated histories that are noncoaxial in three dimensions. In y-sections, counterclockwise rotations of the incremental extension direction are consistent with a bulk shear related to oblique, southwest-directed thrusting with a component of right lateral shear. Chlorite-mica aggregates display ellipsoidal shapes that correspond with the fabric elements; the minor axis of aggregates is perpendicular to S1, the major axis is parallel to L1, and the intermediate axis is parallel to S1 and perpendicular to L1. The porphyroclast shapes are prolate as a consequence of growth in the x-direction. Both incremental strain and finite strains from porphyroclasts indicate a lateral or shallowly northeast-plunging stretch of more than 180%.
|Original language||English (US)|
|Number of pages||18|
|Journal||Journal of the Geological Society of China|
|State||Published - Feb 1 1999|
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