Fülöp R-H, Codilean A T, Wilcken K M, Cohen T J, Fink D, Smith A M, Yang B, Levchenko V A, Wacker L, Marx S K, Stromsoe N, Fujioka T, Dunai T J
School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
Australia's Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia.
Sci Adv. 2020 Jun 19;6(25):eaaz8845. doi: 10.1126/sciadv.aaz8845. eCollection 2020 Jun.
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 Al/Be/C 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.
了解沉积物的搬运和储存如何延迟、减弱甚至消除构造和气候强迫的侵蚀信号，对于我们有效读取和解释地质记录的能力至关重要。在此，我们通过测量现代河流沉积物中宇宙成因铝/铍/碳比率的下游变化，估算了澳大利亚最大的河流系统墨累-达令盆地的沉积物运移时间。结果表明，这些沉积物经历了多次埋藏和再暴露事件，在墨累河和达令河下游，累积滞后时间超过100万年。结合低沉积物供应速率以及覆盖该地区的古老沉积物，我们认为墨累-达令地区的沉积物再循环是一个重要且持续的过程，这将极大地延迟并改变从沉积物腹地传来的外部环境强迫信号。
