Cenozoic basins in northern Taiwan and tectonic implications for the development of the eastern Asian continental margin
Abstract North of Taiwan, four offshore Tertiary basins extend seaward from the inner shelf of the East China Sea to the west of the Okinawa Trough. These basins are characterized by rifting features with NE-SW-trending half-grabens and fault blocks. Episodic rifting events have taken place from Paleocene to Early Miocene with the eastward shift of depositional centers. The Paleogene rift basins are filled primarily with lacustrine to shallow marine sediments, but also contain a slight amount of pyroclastics and basaltic flows. Regional subsidence has dominated during the late Tertiary and these Paleogene half-grabens have united into a large marginal sea basin overlain by a Neogene sedimentary wedge of shallow marine sediments. A fifth basin, the Paleogene Hsuehshan half-graben trough in present-day northern Taiwan has been deformed into mountain ranges by the collision of the Luzon Arc with the eastern Asian margin during the late Cenozoic Era. The tectonic development of eastern Asian margin in northern Taiwan region has evolved into two phases. First, the eastward retreat of the West Pacific subduction zone and accompanied rifting of continental crust occurred during Late Cretaceous to Eocene times. Second, as the intensity of rifting decreased, thermal subsidence of eastern Asian margin prevailed and subsequently caused a tilting seaward continental margin on which a large marginal sea basin rests. Collision of the Luzon Arc with the eastern Asian margin in Taiwan deformed the Paleogene Hseuhshan Trough into mountain ranges (Late Miocene to present)