DOI: 10.1016/j.epsl.2020.116111
论文题名: Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions
作者: Lamy-Chappuis B. ; Heinrich C.A. ; Driesner T. ; Weis P.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 535 语种: 英语
中文关键词: intrusions
; magma
; modeling
; transport
; volatiles
英文关键词: Cooling
; Copper deposits
; Models
; Suspensions (fluids)
; Volcanoes
; intrusions
; Large-scale intrusions
; magma
; Magmatic intrusions
; Physical interactions
; Porphyry copper deposits
; transport
; volatiles
; Transport properties
; cooling
; crystallization
; flow modeling
; fluid inclusion
; igneous intrusion
; magma
; magma chamber
; phase transition
; volatile element
英文摘要: Volatile outgassing from hydrous magma intrusions emplaced and cooling in the Earth's upper crust is key to a number of geologic processes including volcanic eruptions and ore deposition, yet the physical interactions between production, storage and transport of a magmatic volatile phase within magmatic intrusions and their large-scale thermal evolution have remained elusive. We performed numerical simulations of aqueous volatile transport in generic magma chambers as they crystallize in response to conductive and convective cooling and thereby transition from a crystal - volatile - melt suspension to a mush and eventually to a rigid rock. We used simplified but realistic material properties based on published phase equilibrium experiments, published grain-scale modeling results and general geological constraints. We found that the intrusion depth and water content exert decisive control on the rates and mechanisms of intrusion outgassing. Above a critical volatile content, highly permeable capillary tubes develop in crystal mush regions with intermediate crystal volume fractions (∼ 0.5 to 0.7), and such grain-scale tubes provide rapid intrusion-scale degassing paths. These tubes are located in a ring-like mush region inside the intrusion, allowing strongly lateral flow and focusing towards the top of the intrusion. If the water content of the magma is close to saturation at the time of emplacement (5 to 6 wt% H2O) and the depth of the magma chamber roof is at least 4 km deep, initially distributed breakthrough points may coalesce to a single area of fluid release. Large-scale intrusion geometry determines this location of focused fluid release, and cooling rate and size of the intrusion determine overall fluid flux. Feedbacks between local hydrofracturing and heat advection break up the focused fluid expulsion into many short-lived pulses. These conditions for large-scale fluid focusing favor the formation of porphyry copper deposits, but might also trigger caldera-forming ignimbrite eruptions. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165092
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth Sciences, ETH Zurich, Switzerland; GFZ German Research Center for Geosciences, Potsdam, Germany
Recommended Citation:
Lamy-Chappuis B.,Heinrich C.A.,Driesner T.,et al. Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions[J]. Earth and Planetary Science Letters,2020-01-01,535