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The Qilian (祁连) Mountain is an active orogenic belt located at the northeastern margin of the Tibetan Plateau. During the process of continuous convergence between Indian and Eurasian plates, the Qilian Mountain grow correspondingly by means of reaction of old faults and generation of new ones. Here we present apatite fission-track data along a river profile crossing three minor fault (the Minle (民乐)-Damaying (大马营) fault, the Huangcheng (皇城)-Taerzhuang (塔尔庄) fault and the Kangningqiao (康宁桥) fault) which compose the North Qilian fault (NQF) to test the timing and patterns of the fault activities. Apatite fission-track (AFT) results indicate that these minor faults experienced two active phases in the Cretaceous and the Oligocene-Miocene. Further research indicate that the initiation timing of faulting became younger northward in both active periods and the later phase probably more active than the former phase. These tectonic activities might be highly related to the docking of the Lhasa Block to the south in the Cretaceous and uplift and expansion of the Tibetan Plateau in the Cenozoic. [ABSTRACT FROM AUTHOR]

The rate and distribution of deformation along the Qilian Mountain, on the northeastern Tibetan Plateau, is needed to understand the evolution of high topography associated with the plateau. Recently, a number of empirical studies have provided support for the contention, common to most models of fluvial incision, that rock uplift rate exerts a first-order control on the gradient of longitudinal river profiles. Along the northern Qilian Mountain, this method is used to extract information about the spatial patterns of differential rock uplift. Analysis of the longitudinal profiles of bedrock channels reveals systematic differences in the channel steepness index along the trend of the frontal ranges. Local comparisons of channel steepness reveal that lithology and precipitation have limited influence on channel steepness. Similarly, there is little evidence suggesting that channel steepness is influenced by differences in the sediment loads. We argue that the distribution of channel steepness in the Qilian Mountain is mostly the result of differential rates of rock uplift. Thus, channel steepness indices reveal a lower rock uplift rate in the eastern portion of the Qilian Mountain and a higher rate in the middle and west. The highest rates appear to occur in the middle-west portions of the range, just to the west of the Yumu Shan. [ABSTRACT FROM AUTHOR]

Abstract: The uplift rate and pattern of the Qilian Shan Mountain, which lies in the northeast margin of the Tibetan Plateau, are key to understanding the dynamics of crustal deformation in the northeastern Tibetan Plateau. In this work, late Quaternary terraces in seven river valley sections in the eastern Qilian Shan Mountain are studied to determine terrace abandonment ages by OSL (optical simulating luminescence) and terrace heights by GPS (global positioning system) surveys. River incision rates since ~76kaBP are calculated ranging from 0.37mm/a to 1.49mm/a. Distribution of river incision rates shows that higher river incision rates (0.85–1.49mm/a) are located at the rivers'' upstream reaches where mean mountain elevation is ~4000m, and relatively lower incision rates (0.32–0.62mm/a) are located at the mountain front where the mean mountain elevation is <3200m. This difference of the river incision rate reflects spatial difference in rock uplift patterns within the eastern Qilian Shan Mountain. The high mountain range is characterized by a high river incision rate (on average of 1.2±0.4mm/a) and high relief, suggesting high rock uplift rate; whereas the low mountain range is characterized by low river incision rate (on average of 0.5±0.2mm/a) and lower relief, suggesting relatively low rock uplift rate. Based on fault distributions and slip rates, we propose that the differential rock uplift of eastern Qilian Shan is mainly controlled by the thrusting along active thrust faults separating different mountain ranges and by oblique thrusting along strike-slip faults near the mountain crest. [Copyright &y& Elsevier]