Million-year lag times in a post-orogenic sediment conveyor

R-H Fülöp; A T Codilean; K M Wilcken; T J Cohen; D Fink; A M Smith; B Yang; V A Levchenko; L Wacker; S K Marx; N Stromsoe; T Fujioka; T J Dunai

doi:10.1126/sciadv.aaz8845

Million-year lag times in a post-orogenic sediment conveyor

Sci Adv. 2020 Jun 19;6(25):eaaz8845. doi: 10.1126/sciadv.aaz8845. eCollection 2020 Jun.

Authors

R-H Fülöp^{1

2}, A T Codilean^{1

3}, K M Wilcken², T J Cohen^{1

3}, D Fink², A M Smith², B Yang², V A Levchenko², L Wacker⁴, S K Marx¹, N Stromsoe⁵, T Fujioka², T J Dunai⁶

Affiliations

¹ School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
² Australia's Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia.
³ ARC Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, NSW 2522, Australia.
⁴ Ion Beam Physics, ETH-Zürich, Zürich 8093, Switzerland.
⁵ College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT 0909, Australia.
⁶ Institute of Geology and Mineralogy, University of Cologne, Cologne 50674, Germany.

Abstract

Understanding how sediment transport and storage will delay, attenuate, and even erase the erosional signal of tectonic and climatic forcings has bearing on our ability to read and interpret the geologic record effectively. Here, we estimate sediment transit times in Australia's largest river system, the Murray-Darling basin, by measuring downstream changes in cosmogenic ²⁶Al/¹⁰Be/¹⁴C ratios in modern river sediment. Results show that the sediments have experienced multiple episodes of burial and reexposure, with cumulative lag times exceeding 1 Ma in the downstream reaches of the Murray and Darling rivers. Combined with low sediment supply rates and old sediment blanketing the landscape, we posit that sediment recycling in the Murray-Darling is an important and ongoing process that will substantially delay and alter signals of external environmental forcing transmitted from the sediment's hinterland.

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