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The petrology of high-Mg dikes from the Beartooth Mountains, Montana - A search for the parent magma of the Stillwater ComplexSix geochemically distinct groups of Precambrian high-Mg dikes have been examined to determine if any could have been a sample of or closely related to the parent magma of the Stillwater Complex. Only two groups have sufficiently magnesian olivine and orthopyroxene, but neither of these has sufficiently calcic plagioclase. In terms of major elements there appear to be only two distinct magma types: one has a high orthopyroxene component and is petrographically similar to noritic dikes and sills near the Great Dyke of Zimbabwe and the Bushveld Complex of South Africa; the other is similar to primitive tholeiites with higher plagioclase and diopside components than the first. All of the groups are enriched in light-REE and have unusually high K2O concentrations. Model calculations indicate that crustal contamination of fractionating komatiitic magmas is consistent with the major and trace element characteristics of the first magma type. Less extensive contamination of komatiitic magmas may produce the parental magmas of the large layered intrusions.
Document ID
19840035670
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Longhi, J.
(Yale University New Haven, CT, United States)
Wooden, J. L.
(Lunar and Planetary Institute Houston, TX, United States)
Coppinger, K. D.
(Hampshire College Amherst, MA, United States)
Date Acquired
August 12, 2013
Publication Date
November 15, 1983
Publication Information
Publication: Journal of Geophysical Research, Supplement
Volume: 88
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
84A18457
Funding Number(s)
CONTRACT_GRANT: NAGW-175
Distribution Limits
Public
Copyright
Other

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