DOI: 10.1016/j.epsl.2018.01.013
Scopus记录号: 2-s2.0-85044368897
论文题名: Formation of magmatic brine lenses via focussed fluid-flow beneath volcanoes
作者: Afanasyev A. ; Blundy J. ; Melnik O. ; Sparks S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 486 起始页码: 119
结束页码: 128
语种: 英语
英文关键词: brine lens
; electrical resistivity
; magmatic fluid
; ore deposit
; transport in porous medium
Scopus关键词: Degassing
; Electric conductivity
; Flow of fluids
; Geothermal fields
; Hydrodynamics
; Ore deposits
; Porous materials
; Sodium chloride
; Volcanoes
; Electrical conductivity
; High electrical conductivity
; High salinity brines
; Hydrodynamic simulation
; Hydrothermal ore formation
; Magmatic fluids
; Parametric -analysis
; Porous medium
; Transport properties
; brine
; computer simulation
; electrical resistivity
; fluid flow
; formation mechanism
; hydrodynamics
; magmatism
; magnetotelluric method
; numerical model
; ore deposit
; porous medium
; transport process
英文摘要: Many active or dormant volcanoes show regions of high electrical conductivity at depths of a few kilometres beneath the edifice. We explore the possibility that these regions represent lenses of high-salinity brine separated from a single-phase magmatic fluid containing H2O and NaCl. Since chloride-bearing fluids are highly conductive and have an exceptional capacity to transport metals, these regions can be an indication of an active hydrothermal ore-formation beneath volcanoes. To investigate this possibility we have performed hydrodynamic simulations of magma degassing into permeable rock. In our models the magma source is located at 7 km depth and the fluid salinity approximates that expected for fluids released from typical arc magmas. Our model differs from previous models of a similar process because it is (a) axisymmetric and (b) includes a static high-permeability pathway that links the magma source to the surface. This pathway simulates the presence of a volcanic conduit and/or plexus of feeder dykes that are typical of most volcanic systems. The presence of the conduit leads to a number of important hydrodynamic consequences, not observed in previous models. Importantly, we show that an annular brine lens capped by crystallised halite is likely to form above an actively degassing sub-volcanic magma body and can persist for more than 250 kyr after degassing ceases. Parametric analysis shows that brine lenses are more prevalent when the fluid is released at temperatures above the wet granite solidus, when magmatic fluid salinity is high, and when the high-permeability pathway is narrow. The calculated depth, form and electrical conductivity of our modelled system shares many features with published magnetotelluric images of volcano subsurfaces. The formation and persistence of sub-volcanic brine lenses has implications for geothermal systems and hydrothermal ore formation, although these features are not explored in the presented model. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110023
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Institute of Mechanics, Moscow State University, 1 Michurinskiy prospekt, Moscow, 119192, Russian Federation; School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, United Kingdom
Recommended Citation:
Afanasyev A.,Blundy J.,Melnik O.,et al. Formation of magmatic brine lenses via focussed fluid-flow beneath volcanoes[J]. Earth and Planetary Science Letters,2018-01-01,486