TY - JOUR

T1 - Slip Rate of the Danghe Nan Shan Thrust Fault from 10Be Exposure Dating of Folded River Terraces

T2 - Implications for the Strain Distribution in Northern Tibet

AU - Xu, Q.

AU - Hetzel, R.

AU - Hampel, A.

AU - Wolff, R.

N1 - Funding Information: We are indebted to Ryan Gold for kindly generating the digital elevation model used in this study. We thank A. Niehus for her help during preparation of the 10Be samples and the team of Cologne AMS for the timely analysis of all samples. We gratefully acknowledge funding for fieldwork, sample preparation, and AMS analyses provided by the Leibniz Universit?t Hannover (start-up funds to A. Hampel) and the Alexander von Humboldt Foundation (1-year fellowship awarded to Q. Xu). We thank Taylor Schildgen for editorial handling and the Associate Editor, Laura Gregory, and an anonymous reviewer for their comments, which helped to improve the manuscript.

PY - 2021/3/23

Y1 - 2021/3/23

N2 - The northeastward motion of the Tibetan Plateau along the Altyn Tagh strike-slip fault causes thrust faulting in three parallel mountain ranges (Qilian Shan, Daxue Shan, and Danghe Nan Shan) in the plateau interior, and leads to NNE-directed crustal shortening and plateau growth. While slip rates at the plateau margin (i.e., along the Qilian Shan and the Altyn Tagh fault) are well constrained, rates of thrust faulting and the strain distribution in the plateau interior remain poorly resolved. Here, we use field investigations, a high-resolution DEM, and 10Be exposure dating to quantify the shortening rate across the Danghe Nan Shan thrust fault from fluvial terraces, which are deformed by a growing NNE-vergent anticline. 10Be exposure ages from two terrace levels range from 70 ± 5 to 92 ± 7 ka. When combined with uplift values of 37–68 m along the fold hinge, the 10Be ages yield a mean uplift rate of 0.6 ± 0.2 mm/year. Using the cross-sectional area of the fold and the subsurface geometry of the listric thrust fault, we obtain a shortening rate of 0.8 ± 0.2 mm/year, which is consistent with the rate of elastic strain accumulation recorded by GPS data. Together with published fault slip rates and GPS data, our results indicate that northern Tibet experiences NNE-directed shortening at a rate of ∼5 mm/year between the Qaidam Basin and the Hexi Corridor. In the plateau interior, this shortening is accommodated by several range-bounding thrust faults and closely coupled with the eastward decrease in the slip rate of the Altyn Tagh fault.

AB - The northeastward motion of the Tibetan Plateau along the Altyn Tagh strike-slip fault causes thrust faulting in three parallel mountain ranges (Qilian Shan, Daxue Shan, and Danghe Nan Shan) in the plateau interior, and leads to NNE-directed crustal shortening and plateau growth. While slip rates at the plateau margin (i.e., along the Qilian Shan and the Altyn Tagh fault) are well constrained, rates of thrust faulting and the strain distribution in the plateau interior remain poorly resolved. Here, we use field investigations, a high-resolution DEM, and 10Be exposure dating to quantify the shortening rate across the Danghe Nan Shan thrust fault from fluvial terraces, which are deformed by a growing NNE-vergent anticline. 10Be exposure ages from two terrace levels range from 70 ± 5 to 92 ± 7 ka. When combined with uplift values of 37–68 m along the fold hinge, the 10Be ages yield a mean uplift rate of 0.6 ± 0.2 mm/year. Using the cross-sectional area of the fold and the subsurface geometry of the listric thrust fault, we obtain a shortening rate of 0.8 ± 0.2 mm/year, which is consistent with the rate of elastic strain accumulation recorded by GPS data. Together with published fault slip rates and GPS data, our results indicate that northern Tibet experiences NNE-directed shortening at a rate of ∼5 mm/year between the Qaidam Basin and the Hexi Corridor. In the plateau interior, this shortening is accommodated by several range-bounding thrust faults and closely coupled with the eastward decrease in the slip rate of the Altyn Tagh fault.

KW - cosmogenic 10Be

KW - Danghe Nan Shan

KW - fault geometry

KW - folded river terrace

KW - slip rate

KW - Tibet

UR - http://www.scopus.com/inward/record.url?scp=85104570558&partnerID=8YFLogxK

U2 - 10.1029/2020TC006584

DO - 10.1029/2020TC006584

M3 - Article

AN - SCOPUS:85104570558

VL - 40

JO - TECTONICS

JF - TECTONICS

SN - 0278-7407

IS - 4

M1 - e2020TC006584

ER -