GEOTECTONIC EVOLUTION OF LATE CENOZOIC ARC CONTINENT COLLISION IN TAIWAN

The active collision between the Luzon arc and the Asian continent in the Taiwan area is investigated in terms of plate kinematics and geological records. Regarding plate kinematics, the tectonic evolution of the collision can be reconstructed by superimposing the paleopositions of Luzon arc on the pre-collisional Asian continental margin. Regarding geological records, the collisional history can be interpreted from the stratigraphy of the Coastal Range and the Western Foothills and from the diastrophism of the Central Range of Taiwan. By incorporating geological information into plate kinematics, it appears that the Luzon arc could have begun overriding the Asian continental margin in the late Middle Miocene (about 12 Ma). In the Late Miocene, the impingement of the arc deformed part of the continental margin and might have caused metamorphism of part of the Central Range, but no distinct effects were produced in the sedimentary record. In Mio-Pliocene times (about 5 Ma), the arc changed its direction of motion from north-northwesterly to west-northwesterly and began to override the continental margin rapidly. The accretionary wedge grew increasingly to emerge above sea level and feed continental detritus to the Luzon forearc basin and to induce foreland subsidence on the continental margin. In the early Late Pliocene (about 3 Ma), the collision drastically uplifted the mountain ranges in northern Taiwan, which shed voluminous orogenic sediments into the forearc and foreland basins. As the collision propogated toward the west and the south, the forearc and foreland basins were progressively accreted to the collisional orogen which eventually grew up to its present configuration. © 1990.