Cosmogenic nuclides (Be-10 and Al-26) erosion rate constraints in the Badain Jaran Desert, northwest China: implications for surface erosion mechanisms and landform evolution

摘要

Both tectonics and climate affect surface erosion and change the landform. Long-term surface erosion rates determined by in situ produced cosmogenic nuclides are useful quantitative constraints for landform evolution in geological time scale. Measurements of cosmogenic Be-10 and Al-26 in the granitic rocks exposed in the Badain Jaran Desert, give a mean erosion rate of 7.3 +/- 2.6 m/Ma, which is an order of magnitude higher than those reported in other extremely arid regions. Tectonic activity is supposed to be the first order control on regional erosion rate by comparing the 10Be erosion rates of arid regions with different precipitation ranges and tectonic activities worldwide. However the higher erosion rates in the Badain Jaran Desert compared with other arid regions within the stable tectonic background were attributed to the wind erosion and periodically warmer and wetter climate since late Pleistocene. Besides, the estimated eroded mass flux of 7.8 x 10(4) t/y suggests that erosion products of bedrocks in the Badian Jaran Desert only contribute minor desert deposits, which indicates massive exogenous materials input to the desert.