DOI: 10.1016/j.epsl.2021.116988
论文题名: The evolution of lithium isotope signatures in fluids draining actively weathering hillslopes
作者: Golla J.K. ; Kuessner M.L. ; Henehan M.J. ; Bouchez J. ; Rempe D.M. ; Druhan J.L.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 567 语种: 英语
中文关键词: Critical Zone
; lithium isotopes
; reactive transport
; silicate weathering
英文关键词: Catchments
; Dissolution
; Groundwater
; Lithium compounds
; Minerals
; Rivers
; Silicates
; Weathering
; Critical zones
; First order
; Hillslopes
; Isotope signatures
; Lithium isotopes
; Reactive transport
; Secondary mineral formation
; Silicate weathering
; Stable isotopes
; Vadose Zone
; Isotopes
; chemical weathering
; drainage
; fluid
; hillslope
; lithium
; reactive transport
; silicate
; stable isotope
英文摘要: The stable isotopes of lithium (Li) serve as a robust proxy of silicate weathering. The fate and transport of these isotopes in the dissolved load of major rivers have been characterized to infer changes in both contemporary weathering regimes and paleo-conditions. In this contribution, we deconvolve this integrated signal into the individual processes that fractionate Li at the inception of silicate weathering by directly measuring Li isotope ratios of waters (δ7Li) transiting through a rapidly eroding first-order hillslope. We use these data to develop a multicomponent reactive transport framework, which shows that net dissolution of weathered material generates light δ7Li signatures (as low as −9.2‰) in the shallow portion of the vadose zone. An increase in δ7Li deeper into the vadose zone (as much as +18‰) reflects an increasing contribution of secondary mineral formation. Below the water table, congruent weathering occurs and imparts elevated cation concentrations and bedrock δ7Li. Silicate weathering continues within the saturated zone as groundwater travels downslope (δ7Li = +13 to + 24‰) to the stream. The stream signatures (δ7Li = +28 to +29‰) reflect the terminus of this network of silicate weathering reactions and the relative magnitude of each contributing process (e.g., transitions in secondary mineral formation, dissolution of weathered material). We show that fluid progressing through the weathering profile of this first-order hillslope is distinguished by a sequence of characteristic Li isotope signatures, which can be reproduced in a forward, process-based model framework. This model development offers an improved quantitative basis for the use of metal(loid) stable isotopes in disentangling catchment-scale chemical weathering fluxes. © 2021 The Author(s) Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165481
Appears in Collections: 气候变化与战略
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作者单位: Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS, Paris, 75238, France; Section 3.3 Earth Surface Geochemistry, GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, 14473, Germany; Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, United States
Recommended Citation:
Golla J.K.,Kuessner M.L.,Henehan M.J.,et al. The evolution of lithium isotope signatures in fluids draining actively weathering hillslopes[J]. Earth and Planetary Science Letters,2021-01-01,567