The evolutionary history of the Taipei Basin

Speaker: Shao-Chen Hsu

Abstract

For a long time, scholars want to know how to form the Taipei Basin. Therefore, there are many study are published. But the origin of the Taipei Basin remains uncertainties and argument. In this talk, we will talk about Taipei Basin’s evolution modal.
Taipei Basin is floored with deformed Tertiary basement and filled with Quaternary alluvio- lacustrine sediments. It was formed by collision between the China continent and the Luzon Arc in Pliocene-Quaternary time. Prior to the collision, the Basin were part of the subsiding continental shelf, which was later deformed into a mountain range around 2 Ma. At about 0.8 Ma, the subduction polarity flipped in northeastern Taiwan so that the collisional orogeny was terminated and the mountain range began to collapse. Ryukyu arc magmatism produced massive andesitic volcanics in the Tatun area. The Hsingchuang Thrust Fault was transformed into the Shangjiao Normal Fault, and the mountain range on the hanging wall slide down into a depression. At about 0.4Ma, sediment began to accumulate in the Taipei Basin. Since then the Basin has kept expanding as subsidence and sedimentation continued. Throughout its depositional history, the Basin has been dominated by alluvial fans, fluvial plains, and estuaries, which have waxed and waned with the fluctuating sea level. At around 0.2 Ma, the Basin was dammed up as a deep fresh water lake by a pyroclastic flow from the Tatun volcanoes. As the Tahan River was diverted into the Basin at 30Ka, it brought in a large amount of gravelly sediment that laid down huge alluvial fans over the entire Basin. In early Holocene, the Basin was invaded by marine transgression and turned into a brackish-water bay, which was eventually filled up to its present configuration.

References

Teng, L.S., Lee, C.T., Peng, C.-H., Chen, W.-F., Chu, C.-J., 2001. Origin and geological evolution of the Taipei Basin, northern Taiwan. Western Pacific Earth Sciences 1 (2), 115–142.
Song, S.-R., Chen, T.-M., Tsao, S.J., Chen, H.-F., Liu, H.-C., 2007. Lahars in and around the Taipei basin: Implications for the activity of the Shanchiao fault. Jour. Asian Ear. Sci., 31, 3, 277-286.