DOI: 10.1016/j.epsl.2020.116499
论文题名: Transport, survival and modification of xenoliths and xenocrysts from source to surface
作者: Sasse D. ; Jones T.J. ; Russell J.K.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 548 语种: 英语
中文关键词: abrasion
; attrition
; chemical dissolution
; diamond
; impact pits
; kimberlite ascent
英文关键词: Effluent treatment
; Fluidization
; Garnets
; Grain size and shape
; Mechanical stability
; Morphology
; Olivine
; Residence time distribution
; Supercritical fluids
; Velocity
; Volcanic rocks
; Chemical consequences
; Differential velocity
; Grain size distribution
; Grain-size reduction
; Kimberlite magmas
; Mantle minerals
; Mineral surfaces
; Particle velocities
; Transport properties
; basalt
; clinopyroxene
; garnet
; kimberlite
; magma
; mantle
; olivine
; orthopyroxene
; viscosity
; xenolith
英文摘要: A wide variety of magmas entrain, transport and erupt mantle material in the form of xenoliths and xenocrysts. The host magmas are often low viscosity in nature and range from basalt to more esoteric compositions such as kimberlite, nephelinite and basanite. Here we focus on kimberlite magmas which are particularly successful at transporting deep mantle cargo to the surface, including economically important quantities of diamond. Collections of mantle-derived xenoliths and xenocrysts are critical to our understanding of the structure, stability, composition, thermal state, age, and origin of the lithosphere. However, they also inform on magma transport conditions. Through a series of scaled analogue experiments, we document the relative mechanical stability of olivine, garnet, orthopyroxene, clinopyroxene and diamond xenocrysts during magma ascent. Our experiments fluidized these mantle minerals at a constant gas flux for variable amounts of time approximating transport in a high velocity, turbulent, fluid-rich (supercritical fluid or gas, depending on depth) magma. The evolution of mineral surface features, morphology and grain size distributions is analyzed as a function of residence time. We show that on timescales consistent with magma ascent, each mantle mineral is subject to mechanical modification resulting in mass loss and reshaping (rounding) by grain size reduction and surface pitting. We further discuss the chemical consequences of producing fine particle chips that are highly susceptible to dissolution. Lastly, we utilize an empirical model that relates textural observations (e.g. impact pit size) on xenocrysts to differential particle velocities. Our approach applied to natural kimberlitic olivine and garnet xenocrysts indicates differential velocities of ∼4ms−1 – the first direct estimate for velocity in an ascending kimberlite magma. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165255
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth, Ocean & Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, L69 3GP, United Kingdom
Recommended Citation:
Sasse D.,Jones T.J.,Russell J.K.. Transport, survival and modification of xenoliths and xenocrysts from source to surface[J]. Earth and Planetary Science Letters,2020-01-01,548