TY  - JOUR
A1  - Hetzel, Ralf
A1  - Niedermann, Samuel
A1  - Tao, Mingxin
A1  - Kubik, Peter W.
A1  - Strecker, Manfred
T1  - Climatic versus tectonic control on river incision at the margin of NE Tibet: Be-10 exposure dating of river terraces at the mountain front of the Qilian Shan
T2  - Journal of geophysical research : Earth surface
N2  - [1] We document late Pleistocene - Holocene aggradation and incision processes at the mountain front of the Qilian Shan, an active intracontinental fold-and-thrust belt accommodating a significant portion of the India-Asia convergence. The Shiyou River cuts through a NNE vergent fault propagation fold with Miocene red beds in the core and Pliocene - Quaternary growth strata on the northern forelimb. South of the anticline, Miocene strata dip 20 degrees SSW, suggesting a similar orientation for the basal decollement. After aggradation of an similar to 150-m-thick, late Pleistocene valley fill, the Shiyou River formed three terraces. The highest terrace, located 170 m above the river, constitutes the top of the fill. The other terraces are fill cut terraces: their treads are located 130 - 105 m and 37 m above the river, respectively. The 10 Be exposure dating of the terraces suggests that river incision accelerated from 0.8 +/- 0.2 mm yr(-1) to similar to 10 mm yr(-1) at 10 - 15 kyr. We interpret fast Holocene river incision as largely unrelated to tectonic forcing. The late Pleistocene incision rate of 0.8 +/- 0.2 mm yr(-1) places an upper limit of 2.2 +/- 0.5 mm yr(-1) on the horizontal shortening rate, assuming that incision is solely caused by rock uplift above a decollement dipping 20 degrees. However, the actual shortening rate may lie between similar to 2.2 mm yr(-1) and zero because deformation of the terraces and the valley fill cannot be unequivocally demonstrated. Our estimate is consistent with the bulk shortening rate of similar to 5 - 10 mm yr(-1) across several faults in NE Tibet derived from neotectonic and GPS data, although in case of the Shiyou River, Holocene deformation is barely discernible owing to intense climate-induced river incision.
Y1  - 2006
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/47000
SN  - 2169-9003
SN  - 2169-9011
VL  - 111
PB  - Union
CY  - Washington
ER  -