Deciphering the rate of mountain growth during topographic presteady state: An example from the NE margin of the Tibetan Plateau

Abstract

We use field investigations, topographic profiles, and 10Be exposure dating to constrain the growth rate of the Yumu Shan, a thrust-bounded mountain range at the northeastern margin of Tibet. Wind gaps, fault scarps at the mountain front, and hanging paleocatchments indicate that the Yumu Shan is growing both laterally and vertically. Scarp profiles and 10Be ages yield rock uplift rates of ∼500 and ∼800 mm ka-1 for the eastern and central parts of the range, respectively. The fact that the rock uplift rate in the high center of the Yumu Shan exceeds catchment- wide 10Be denudation rates, which range from ∼180 to ∼280 mm ka-1, indicates that the mountain range continues to rise and has not yet reached a topographic steady state. Combining the total structural relief of the range with the rates of rock uplift and denudation suggests that the growth of the Yumu Shan started 3.7 ± 0.9 Ma ago. Copyright 2009 by the American Geophysical Union.