T53A-05
Geomorphic Indices and Differential Uplift Patterns in the Southern Central Range, Taiwan
Friday, 18 December 2015: 14:40
304 (Moscone South)
Chung Huang1, William B Ouimet2, Timothy B Byrne3, Hsin Tung1, Yi-Wei Chen4 and Jyr-Ching Hu4, (1)Department of Geoscience, National Taiwan University, Taipei, Taiwan, (2)University of Connecticut, Storrs, CT, United States, (3)University of Connecticut, Groton, CT, United States, (4)National Taiwan University, Taipei, Taiwan
Abstract:
The southern Central Range of Taiwan is an active orogeny. The uplift rate measured by recent geodetic survey ranges from 10 to 20 mm/yr. The geodetic benchmarks in the southern Central Range can be only deployed on the major highways because the rough topography makes the survey and maintenance of benchmarks more difficult. Due to the uneven distribution of benchmarks, the surface displacement data is limited in two mountain-crossing highways and edge of the mountain, so the deformation pattern in the center of the southern Central Range is not clear.
In order to understand the comprehensive deformation pattern of the southern Central Range, we then use the geomorphic indices to describe the differential uplift pattern of the active orogeny. The geomorphic indices can reflect the surface deformation, which can help us to reconstruct the deformation pattern in the areas without geodetic measurements. The following two geomorphic indices are used in the study, river steepness index (ksn) and basin asymmetry factor (AF). We first use the two indices to describe the overall surface deformation pattern of the southern Central Range, then we focus on the geomorphic indices an active antiform area. The active antiform is revealed by a geodetic surveying line along the Laonung River which is oblique to the axis of this slate antiform, and the maximum uplift rate is around 11 to 12 mm/yr. The incision rate of Laonung River calculated from terrace dating shows the uplift rate of the antiform is 18 to 19 mm/yr for the past 2000 years.
The result shows the ksn pattern of the southern Central Range can be correlated with uplift rate, and the AF can be correlated with the differential uplift from north to south of the southern Central Range. The ksn in the active antiform area also shows the higher ksn is linked to higher uplift rate, and the AF values around the antiform shows the forelimb of the active antiform is tilted more than the crest.
