The sedimentary evolution of peripheral foreland basin and a case study in Taiwan
Shao-Ping Chiang
Abstract
Foreland basin is a sedimentary basin that lies between the orgenic belt and craton. There are two types of foreland basins, peripheral foreland basins and retro-arc foreland basins, respevtively. Retro-arc foreland basins locates behind a compressional arc in contrast to peripheral foreland basin which formed on the subducting plate during arc-continent or continent-continent collision.
The Taiwan foreland basin has been formed on top of the subducting Eurasian plate since 6.5 Ma due to lithospheric flexure by the overriding Luzon arc and orogenic loading. This foreland basin is developed on top of a passive margin and hence is a peripheral foreland basin. Several lines of evidence show the transitional sedimentation from passive margin to foreland basin: change in paleocurrent directions, reworked nannofossils and first occurrence of Taiwan mountain-derived clasts at about 4Ma. During the early stage of arc-continent collision, the orogenic belt was subdued while the basin was characterized by rapid basement subsidence. This resulted in deep-water basin fills. During a later stage, still rapid basement subsidence has been coupled by rapid sedimentation as large amount of sediments have been shed from Taiwan mountain belts. This has resulted in shallow marine and continental basin fills. The rapid basement subsidence has been compensated by rapid sedimentation and filling up of the basin, suggesting a steady state of the foreland basin has been achieved while the foreland basin has been migrating toward the craton in the west.
Sinclair reviewed the sedimentation of peripheral foreland basins during their early development and suggested a concept called ¡§underfilled trinity¡¨ to exemplify the sedimentary features during the early development of a peripheral foreland basin. ¡§Underfilled trinity¡¨ means that there are three units in early foreland sequence: carbonate deposition on the cratonic margin of the basin (the lower unit); hemipelagic mud sedimentation offshore from the cratonic margin of the basin (the middle unit); and deep water trubiditic siliciclastic sedimentation toward the orogenic margin of the basin (the upper unit).
During the later development of the peripheral foreland basin, thrusts propagated well into the continental margin and orogenic belts become emerged, basin filled with lots of sedments due to high rates of uplift and erosion of the mountain belt. Basin becomes overfilled and the sedimentary environment becomes continental facies.
Reference
Covey, M., 1986, The evolution of foreland basins to steady state: Evidence from the western Taiwan foreland basin, in Allen, P. A., and Homewood, P., eds., Foreland basins: International Association of Sedimentologists Special Publication 8, 77¡V90.
(Abstract) (Full text)
Sinclair, H. D., 1997, Tectonostratigraphic model for underfilled peripheral foreland basins: An Alpine perspective. GSA Bulletin, 3, 324¡V346.