DOI: 10.1016/j.epsl.2017.12.029
Scopus记录号: 2-s2.0-85044787331
论文题名: Serpentinization as a reactive transport process: The brucite silicification reaction
作者: Tutolo B.M. ; Luhmann A.J. ; Tosca N.J. ; Seyfried W.E. ; Jr.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 484 起始页码: 385
结束页码: 395
语种: 英语
英文关键词: aqueous geochemistry
; hydrothermal
; reactive transport
; serpentinization
; silica
Scopus关键词: Geochemistry
; Groundwater flow
; Magnesite
; Olivine
; Serpentine
; Silica
; Silicate minerals
; Silicon
; Talc
; Aqueous geochemistry
; Fundamental constraints
; hydrothermal
; Reactive transport
; Reactive transport experiments
; Reactive transport process
; Serpentinization
; Spatial and temporal scale
; Transport properties
; brucite
; concentration (composition)
; geochemistry
; hydrothermal fluid
; reactive transport
; serpentinization
; silica
; silicification
英文摘要: Serpentinization plays a fundamental role in the biogeochemical and tectonic evolution of the Earth and perhaps many other rocky planetary bodies. Yet, geochemical models still fail to produce accurate predictions of the various modes of serpentinization, which limits our ability to predict a variety of related geological phenomena over many spatial and temporal scales. Here, we use kinetic and reactive transport experiments to parameterize the brucite silicification reaction and provide fundamental constraints on SiO2 transport during serpentinization. We show that, at temperatures characteristic of the sub-seafloor at the serpentinite-hosted Lost City Hydrothermal Field (150 °C), the assembly of Si tetrahedra onto MgOH2 (i.e., brucite) surfaces is a rate-limiting elementary reaction in the production of serpentine and/or talc from olivine. Moreover, this reaction is exponentially dependent on the activity of aqueous silica (aSiO2(aq)), such that it can be calculated according to the rate law: Rate=2.3×10−4aSiO2(aq) 1.5(mol/m2/s). Calculations performed with this rate law demonstrate that both brucite and Si are surprisingly persistent in serpentinizing environments, leading to elevated Si concentrations in fluids that can be transported over comparatively large distances without equilibrating with brucite. Moreover, applying this rate law to an open-system reactive transport experiment indicates that advection, preferential flow pathways, and reactive surface area armoring can diminish the net rate of Si uptake resulting from this reaction even further. Because brucite silicification is a fundamentally rate-limiting elementary reaction for the production of both serpentine and talc from forsterite, our new constraints are applicable across the many environments where serpentinization occurs. The unexpected but highly consequential behavior of this simple reaction emphasizes the need for considering serpentinization and many other hydrothermal processes in a reactive transport framework whereby fluid, solute, and heat transport are intimately coupled to kinetically-controlled reactions. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110079
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
There are no files associated with this item.
作者单位: University of Oxford, Department of Earth Sciences, South Parks Road, Oxford, OX1 3AN, United Kingdom; Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, United States; Department of Earth Sciences, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, MN 55455, United States; University of Calgary, Department of Geoscience, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada
Recommended Citation:
Tutolo B.M.,Luhmann A.J.,Tosca N.J.,et al. Serpentinization as a reactive transport process: The brucite silicification reaction[J]. Earth and Planetary Science Letters,2018-01-01,484