DOI: 10.1038/ngeo2534
论文题名: Open-system dynamics and mixing in magma mushes
作者: Bergantz G.W. ; Schleicher J.M. ; Burgisser A.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2015
卷: 8, 期: 10 起始页码: 793
结束页码: 796
语种: 英语
Scopus关键词: crystal structure
; discrete element method
; fault
; fluid dynamics
; fluid flow
; granular medium
; magma chamber
; mixing
; numerical model
; reservoir
; viscoplasticity
英文摘要: Magma dominantly exists in a slowly cooling crystal-rich or mushy state. Yet, observations of complexly zoned crystals, some formed in just one to ten years, as well as time-transgressive crystal fabrics imply that magmas mix and transition rapidly from a locked crystal mush to a mobile and eruptable fluid. Here we use a discrete-element numerical model that resolves crystal-scale granular interactions and fluid flow, to simulate the open-system dynamics of a magma mush. We find that when new magma is injected into a reservoir from below, the existing magma responds as a viscoplastic material: fault-like surfaces form around the edges of the new injection creating a central mixing bowl of magma that can be unlocked and become fluidized, allowing for complex mixing. We identify three distinct dynamic regimes that depend on the rate of magma injection. If the magma injection rate is slow, the intruded magma penetrates and spreads by porous media flow through the crystal mush. With increasing velocity, the intruded magma creates a stable cavity of fluidized magma that is isolated from the rest of the reservoir. At higher velocities still, the entire mixing bowl becomes fluidized. Circulation within the mixing bowl entrains crystals from the walls, bringing together crystals from different parts of the reservoir that may have experienced different physiochemical environments and leaving little melt unmixed. We conclude that both granular and fluid dynamics, when considered simultaneously, can explain observations of complex crystal fabrics and zoning observed in many magmatic systems. © 2015 Macmillan Publishers Limited. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106162
Appears in Collections: 气候减缓与适应 科学计划与规划
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作者单位: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA, United States; Institut des Sciences de la Terre, CNRS-IRD-Université de Savoie, Campus Scientifique, Le Bourget du Lac, France
Recommended Citation:
Bergantz G.W.,Schleicher J.M.,Burgisser A.. Open-system dynamics and mixing in magma mushes[J]. Nature Geoscience,2015-01-01,8(10)