DOI: 10.1016/j.epsl.2020.116448
论文题名: The distribution of sediment residence times at the foot of mountains and its implications for proxies recorded in sedimentary basins
作者: Carretier S. ; Guerit L. ; Harries R. ; Regard V. ; Maffre P. ; Bonnet S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 546 语种: 英语
中文关键词: grain
; landscape evolution modelling
; paleo-environmental proxy
; piedmont rivers
; residence time
英文关键词: Geochemistry
; Landforms
; Recycling
; Sedimentology
; Sediments
; Settling tanks
; Stochastic systems
; Distribution of grains
; Environmental conditions
; Geochemical methods
; Landscape evolutions
; Long residence time
; Mean residence time
; Sedimentary strata
; Terrigenous sediment
; Residence time distribution
; deposition
; landscape evolution
; mountain region
; paleoenvironment
; residence time
; sediment chemistry
; sediment property
; sedimentary basin
; spatial distribution
英文摘要: The geochemical and physical properties of terrigenous sediment stacked in sedimentary basins are used as proxies for the paleo-environmental conditions that prevailed during their period of deposition. Nevertheless, sediment grains have a stochastic transit from mountain sources to sedimentary basins: a fraction of grains are stored for a long time while others are recycled from old deposits. Consequently, the temporal representativity of a population of grains in a sedimentary stratum is uncertain. The potential recycling of old material is a major concern in the reconstruction of paleo-environments and this recycling is usually difficult to evaluate. In particular, the distribution of grain residence times in basins, between sources and sinks, is out of reach. Here we use a landscape evolution model that traces grains to analyse the distribution of residence times in an alluvial apron at the foot of a mountain relief. We study an end-member scenario that is the least favourable for the storage of grains: when the mountain is eroding at the same rate as rock is uplifting. In this case, the alluvial apron behaves as a by-pass zone, when averaging sediment flux over Ma, and the storage of grains of any size should be minimal. Yet, the model predicts that some grains are stored for hundreds of thousands of years before exiting the alluvial apron. Consequently, the mean residence time of sediment grains is much higher than the observed residence time of 95% of the grains exported by the alluvial apron rivers. This process may explain very long residence times found in fluvial systems by geochemical methods based on bulk measurements of sediment. Furthermore, it suggests that grains stored for a very long time, although a minority, can bias time-dependent proxies. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164904
Appears in Collections: 气候变化与战略
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作者单位: GET, Université de Toulouse, IRD, UPS, CNRS, Toulouse, France; University of Rennes, CNRS, Géosciences Rennes, UMR 6118, France; Research Center for Integrated Disaster Risk Management (CIGIDEN), PUC, Santiago, Chile; Department of Earth and Planetary Science, University of California, Berkeley, United States
Recommended Citation:
Carretier S.,Guerit L.,Harries R.,et al. The distribution of sediment residence times at the foot of mountains and its implications for proxies recorded in sedimentary basins[J]. Earth and Planetary Science Letters,2020-01-01,546