Erosion in northwest Tibet from in-situ-produced cosmogenic Be-10 and Al-26 in bedrock
No Thumbnail Available
Date
2007-01
Journal Title
Journal ISSN
Volume Title
Publisher
John Wiley & Sons
Abstract
Concentrations of in-situ-produced cosmogenic nuclides Be-10 and Al-26 in quartz were measured by accelerator mass spectrometry for bedrock basalts and sandstones located in northwest Tibet. The effective exposure ages range between 23 and 134 ka (Be-10) and erosion rates between 4.0 and 24 mm ka(-1). The erosion rates are significantly higher than those in similarly and Antarctica and Australia, ranging between 0.1 and 1 mm ka(-1), suggesting that precipitation is not the major control of erosion of landforms. Comparison of erosion rates in and regions with contrasting tectonic activities suggests that tectonic activity plays a more important role in controlling long-term erosion rates. The obtained erosion rates are, however, significantly lower than the denudation rate of 3000-6000 mm ka(-1) beginning at c. 53 Ma in the nearby Godwin Austen (K2) determined by apatite fission-track thermochronology. It appears that the difference in erosion rates within different time intervals is indicative of increased tectonic activity at c. 5-3 Ma in northwest Tibet. We explain the low erosion rates determined in this study as reflecting reduced tectonic activity in the last million years. A model of localized thinning of the mantle beneath northwest Tibet may account for the sudden increased tectonic activity at c. 5-3 Ma and the later decrease. © 2006, John Wiley & Sons Ltd.
Description
Keywords
Erosion, Tibet, Beryllium, Aluminium, Tectonics, In-situ processing
Citation
Kong, P., Na, C. G., Fink, D., Ding, L., & Huang, F. X. (2007). Erosion in northwest Tibet from in-situ-produced cosmogenic Be-10 and Al-26 in bedrock. Earth Surface Processes and Landforms, 32(1), 116-125. doi:10.1002/esp.1380