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DOI	10.1016/j.earscirev.2020.103147
	A global rate of denudation from cosmogenic nuclides in the Earth's largest rivers
	Wittmann H.; Oelze M.; Gaillardet J.; Garzanti E.; von Blanckenburg F.
发表日期	2020
ISSN	00128252
卷号	204
英文摘要	Cosmogenic nuclide analysis in sediment from the Earth's largest rivers yields mean denudation rates of the sediment-producing areas that average out the local variations commonly found in small rivers. Using this approach, we measured in situ cosmogenic 26Al and 10Be in sand of >50 large rivers over a range of climatic and tectonic regimes covering 32% of the Earth's terrestrial surface. In 35% of the analyzed rivers, we find 26Al/10Be ratios significantly lower than these nuclides´ surface-production-rate ratio of 6.75 in quartz, indicating radioactive decay over periods exceeding 0.5 Myr. We invoke a combination of slow erosion, shielding in the source area, and sediment storage and burial during long-distance transport to explain these low ratios. In the other 65% of studied rivers we find 26Al/10Be ratios within uncertainty of their surface production-rate ratio, indicating cosmogenic steady state. For these rivers, we obtain a global source area denudation rate of 141 t/km2×yr (54 mm/kyr of rock-equivalent) that translates to a flux of 3.07 ± 0.56 Gt/yr. By assuming that this sub-dataset is representative of the global land surface, we upscale this value to the total surface area for exorheic basins, thereby obtaining a global denudation flux of 15.2 ± 2.8 Gt/yr that integrates over the past 11 kyr. This value is slightly lower than published values from cosmogenic nuclides from small river basins (23 (+53/−16)) Gt/yr) upscaled using a global slope model, and also lower than modern sediment and dissolved loads exported to the oceans (24.0 Gt/yr). Our new approach confirms an estimate of global dissolved and solid matter transfer that converges to an encouragingly narrow range of within 35%; whereas the use of paired nuclides in large rivers provides estimates of the buffering timescales of sediment transport. © 2020 Elsevier B.V.
英文关键词	cosmogenic radionuclide; denudation; fluvial deposit; quartz; sediment transport
语种	英语
来源期刊	Earth Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203931
作者单位	GFZ German Research Centre for Geosciences, Potsdam, Germany; Institut de Physique du Globe, Paris, France; Department of Earth and Environmental Sciences, Università di Milano-Bicocca, Milano, Italy; Institute of Geological Sciences, Freie Universität Berlin, Germany
推荐引用方式 GB/T 7714	Wittmann H.,Oelze M.,Gaillardet J.,et al. A global rate of denudation from cosmogenic nuclides in the Earth's largest rivers[J],2020,204.
APA	Wittmann H.,Oelze M.,Gaillardet J.,Garzanti E.,&von Blanckenburg F..(2020).A global rate of denudation from cosmogenic nuclides in the Earth's largest rivers.Earth Science Reviews,204.
MLA	Wittmann H.,et al."A global rate of denudation from cosmogenic nuclides in the Earth's largest rivers".Earth Science Reviews 204(2020).