DOI: 10.1016/j.tecto.2021.228972
论文题名: Textural insights into the significance of ophiolitic chromitites, with special reference to Oman
作者: Boudier F. ; Mainprice D. ; Nicolas A. ; Barou F.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2021
卷: 814 语种: 英语
中文关键词: Chromite crystallization
; Crystal preferred orientation
; Melt circulation
; Misorientation at grain boundary
; Semail ophiolite
; Upper mantle dynamics
英文关键词: Crystal orientation
; Crystals
; Grain boundaries
; Olivine
; Crystal preferred orientations
; Dislocation creep
; Fluid circulation
; High temperature
; Micro-structural
; Mis-orientation
; Random boundaries
; Ultrahigh pressure
; Chromite deposits
; chromite
; chromitite
; crystallization
; formation mechanism
; melt
; metallogenesis
; microstructure
; ophiolite
; ore deposit
; source rock
; texture
; upper mantle
; Oman
英文摘要: This paper analyses the process and depth of formation of chromite crystals occasionally including ultrahigh pressure (UHP) minerals, recovered from some investigated ophiolites. We present direct microstructural evidence for crystallization of chromite ores from the Semail ophiolite, in place they are exposed. Similar crystal preferred orientation in olivine-rich layers and in septa from chromite layers indicate deformation of the olivine solid frame by dislocation creep at high temperature, synchronous with the crystallization of chromite. The preservation of the olivine framework throughout the development of joined chromite grains suggests that chromite replaced olivine. Chromite grains crystallized from a melt circulating in an open-system, stress-bearing network of dunitic aggregate, controlled by the olivine high-T slip system. The misorientation of joined crystals at grain boundaries define the ratio of twin vs. random boundaries that were closed to vs. open to fluid circulation, respectively, suggesting that chromite layers may represent planes of channelized melt circulation. The relationship of chromite deposits to ridge tectonics structures suggests that Cr-bearing melt was produced at the transition from an active spreading ridge to deep mantle shear zones acting as possible source of hydration. The occurrence of potential UHP inclusions in chromite crystals is assigned to continental contamination of melts ascending through the Arabian margin. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170780
Appears in Collections: 气候变化与战略
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作者单位: Geosciences Montpellier, CNRS & Université de Montpellier 2, Montpellier, F-34095, France
Recommended Citation:
Boudier F.,Mainprice D.,Nicolas A.,et al. Textural insights into the significance of ophiolitic chromitites, with special reference to Oman[J]. Tectonophysics,2021-01-01,814