气候变化领域集成服务门户(CCPortal): Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions

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DOI	10.1016/j.epsl.2020.116111
	Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions
	Lamy-Chappuis B.; Heinrich C.A.; Driesner T.; Weis P.
发表日期	2020
ISSN	0012821X
卷号	535
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.
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202714
作者单位	Department of Earth Sciences, ETH Zurich, Switzerland; GFZ German Research Center for Geosciences, Potsdam, Germany
推荐引用方式 GB/T 7714	Lamy-Chappuis B.,Heinrich C.A.,Driesner T.,et al. Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions[J],2020,535.
APA	Lamy-Chappuis B.,Heinrich C.A.,Driesner T.,&Weis P..(2020).Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions.Earth and Planetary Science Letters,535.
MLA	Lamy-Chappuis B.,et al."Mechanisms and patterns of magmatic fluid transport in cooling hydrous intrusions".Earth and Planetary Science Letters 535(2020).