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We present the results of determinations of the ellipsoids of magnetic susceptibility anisotropy and of the paleomagnetic directions for 17 sedimentary rock sites of the northeastern collision belt of Taiwan.

Detailed studies of fracture patterns and paleostress reconstructions based on analyses of fault-slip data sets allow identification of four main patterns of compressional paleostress orientations in the Cenozoic rocks of northern Taiwan. These patterns correspond to five successive tectonic events dominated by (1) N-S, (2) WSW-ENE, (3) WNW-ESE, (4) NW-SE and (5) WNW-ESE directions of compression. The first two events are characterized by relatively minor structures in the foreland fold-and-thrust belt; the first event probably reflects major left-lateral shear along NNE-SSW trends which occurred in the adjacent eastern metamorphic belt during the middle-late Miocene. These first two events do not affect the Plio-Pleistocene in the localities studied. In contrast, the last three events created the major compressional structures of the foreland belt during the Plio-Pleistocene collision in Taiwan. Preliminary studies suggest that the magnetic fabric of the rocks has been significantly influenced by compressional deformation along WNW-ESE and NW-SE trends, especially in the Slate Belt, thus confirming the importance of these last three events.