Holocene uplift and subsidence along an active tectonic margin southwestern Taiwan

Abstract

Taiwan is located along a convergent plate boundary, where the Luzon Arc collides with the Eurasia continental margin. The Tainan Plain of southwestern Taiwan is incorporated into and deformed by a regional fold-and-thrust belt associated with this convergent plate margin. In this study we establish a tentative regional Holocene relative sea-level curve that allows us to analyze crustal uplift and subsidence rates of the Tainan Plain. The maximum Holocene uplift rates on the Tainan Plain occur on the Tainan Tableland and the Chungchou Terrace. These two areas have experienced long-term (Holocene) uplift rates of 5 and 7 mm/yr, respectively. The Tawan Lowland, located between these two areas, is subsiding at a long-term rate of about 1 mm/yr. Based on this pattern of the crustal movement, the Tainan Tableland is interpreted as a mud diapiric dome, and the Chungchou Terrace as the product of a blind thrust fault. The Holocene reference sea-level curve proposed in this study can be used to determine the pattern of crustal movements elsewhere in Taiwan. It also can suggest that the Holocene terrace development does not occur in area where the uplift rate exceeds 8 mm/yr, while late Holocene regression, the general trend around the western Pacific, is not recorded where the rate of subsidence is lower than 1 mm/yr.