Erosion in northwest Tibet from in‐situ‐produced cosmogenic ¹⁰Be and ²⁶Al in bedrock

Abstract

Concentrations of in-situ-produced cosmogenic nuclides 10

<sup>10</sup>Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

“…0.04 to 0.2 mm yr −1 ). These low denudation rates are of the same order of magnitude as previously published bedrock and detrital denudation rates in other areas of the plateau (Lal et al, 2004;Kong et al, 2007;Hetzel et al, 2011;Strobl et al, 2012;Li et al, 2014;Rades et al, 2015). The slightly higher denudation rates measured for the two northern tributaries, the Lhasa-He (Kyi) (pt.…”

Too young or too old: Evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages

“…Figure 4c shows the exposure age pattern adopting a maximum duration of prior exposure of 150 ka and a maximum prior sample depth of 5 m. The 150 ka maximum prior exposure duration is based on exposure ages of bedrock surface samples collected from unglaciated areas on the Tibetan Plateau (Kong et al, 2007;Lal et al, 2003;Supplementary Fig. S7; Supplementary Dataset).…”

Landscape evolution of a bedrock peneplain on the southern Tibetan Plateau revealed by in situ-produced cosmogenic 10Be and 21Ne

“…Although the study by Lal et al (2003) suggests that rates of bedrock erosion on the Tibetan Plateau are low, the limited geologic and geomorphic information provided on the studied sites precludes a detailed interpretation of their data. A second study in western Tibet (80°E, 35°N) focussed on mafic volcanic cones that contain quartz xenocrysts (Kong et al, 2007). The erosion rates inferred from 10 Be and 26 Al concentrations in ten quartz samples from these cones range from 4 to 24 m Ma -1 and support the view that bedrock is generally eroding at low rates.…”

“…In order to allow a direct comparison of our data with those of previous studies (Lal et al, 2003;Kong et al, 2007), we used the constant production rate scaling model of Lal (1991) -Stone (2000 in the online calculator. The local 10 Be denudation rates obtained from bedrock exposures and bedrock blocks vary from 2.7 to 20.2 m Ma -1 , whereas the amalgamated clast and grus samples cluster between 5.3 and 14.2 m Ma -1 (mean = 8.1 m Ma -1 ) (Fig.…”

“…The erosion rates inferred from 10 Be and 26 Al concentrations in ten quartz samples from these cones range from 4 to 24 m Ma -1 and support the view that bedrock is generally eroding at low rates. Interestingly, five of the investigated samples indicated a complex exposure history with significant periods of burial, which may result from a prolonged cover by ice or snow (Kong et al, 2007).…”