Abstract
The weathering of continental surfaces and the transport of sediments via rivers into the oceans is an integral part of the dynamic processes that shape the Earth's surface. To understand how tectonic and climatic forcings control regional rates of weathering, we must be able to identify their effects on sedimentary archives over geologic timescales. Cosmogenic nuclides are a valuable tool to study rates of surface processes and have long been applied in fluvial systems to quantify basin-wide erosion rates. However, in large rivers, continual processes of erosion and deposition during sediment transport make it difficult to constrain how long sediments spend within the fluvial system. In this study, we examine the role of rivers in buffering erosional signals by constraining the timescales of fluvial transport in large rivers across the world. We apply a stochastic numerical model based on measurements of cosmogenic nuclides concentrations and calculate sediment residence times of 104–105 years in large rivers. These timescales are equal to or longer than climatic cycles, implying that changes to rates of erosion brought on by climatic variations are buffered during transport in large rivers and may not be recognizable in the sedimentary record.
Original language | American English |
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Article number | e2021JF006417 |
Journal | Journal of Geophysical Research: Earth Surface |
Volume | 127 |
Issue number | 5 |
DOIs | |
State | Published - May 2022 |
Bibliographical note
Funding Information:This research was supported by the Israel Science Foundation Individual Research Grant No. 385/14 to A. Matmon. This work was partially supported by the BSF Prof. Rahamimoff Travel Grant for Young Scientists to M. Ben‐Israel. M. Armon was supported by an ETH Zürich Postdoctoral Fellowship (Project No. 21‐1 FEL‐67), by the Stiftung für naturwissenschaftliche und technische Forschung and the ETH Zürich Foundation. The authors would also like to thank Aaron Sims and Yonaton Goldschmidt for their assistance in the field and Yona Geller and Ofir Tirosh for their help with sample preparation. Lastly, the authors appreciate all the hard work and constructive comments by Laure Guerit, Hugh Sinclair, Marisa Repasch, and anonymous reviewers.
Publisher Copyright:
© 2022 The Authors.
Keywords
- cosmogenic nuclides
- fluvial transport
- large rivers
- residence time
- sediment transport
- signal buffering