Dating of erosion surface and terraces in the eastern Qilian Shan, northwest China

The actively deformed foreland of eastern Qilian Shan (mountains) contains well-preserved geomorphic features such as erosion surfaces, river terraces and tectonically uplifted alluvial fans, providing suitable archives for research on regional tectonic activities and palaeoclimatic changes. These geomorphic surfaces are well dated by using a combination of magnetostratigraphy, electron spin resonance, thermoluminescence, infra-red stimulated luminescence, radiocarbon dating, and correlation with the well-established loess-palaeosol sequences of China. Our results show that the erosion surface formed about 1.4 Ma ago, and the age of river terraces is 1.24 Ma, 820-860 ka, 780 ka, 420-440 ka, 230-250 ka, 140 ka, 60 ka and 10 ka, respectively. Valley incision rates of e. 0.09-0.25 m ka(-1) have been identified. The repetitive stratigraphic and geomorphic pattern of these terraces indicates the fluvial sedimentation-incision cycles are tightly associated with the 100-ka glacial-interglacial climatic cycles. Copyright (c) 2006 John Wiley & Sons, Ltd