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Magnesian anorthosites and associated troctolites and dunite in Apollo 14 brecciasMagnesian anorthosite, a new type of pristine lunar highlands rock, has been found in Apollo 14 breccias. It has primitive (high Ca and Mg) silicate mineral compositions, and high and variable REE concentrations. Variations in REE contents can be accounted for by variations in modal abundance of REE-rich apatite. Magnesian anorthosites are associated with troctolites and a dunite with very similar mineral compositions and it is suggested that all crystallized from a differentiated troctolitic intrusion. The origin of the REE-rich apatite is enigmatic. It is unlikely to have crystallized from an igneous liquid in equilibrium with the major minerals in the anorthosite. Possible origins are assimilation of urKREEP or metasomatism by REE-rich fluids. REE-rich alkali anorthosites and gabbronorites are also found and are likely to be related to KREEP basalt magmas. Lunar compositional associations are distributed in a regional rather than global manner.
Document ID
19850035504
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lindstrom, M. M.
(Washington University St. Louis, MO, United States)
Knapp, S. A.
(Tennessee Univ. Knoxville, TN, United States)
Shervais, J. W.
(Tennessee Univ. Knoxville, TN, United States)
Taylor, L. A.
(Tennessee, University Knoxville, TN, United States)
Date Acquired
August 12, 2013
Publication Date
November 15, 1984
Publication Information
Publication: Journal of Geophysical Research, Supplement
Volume: 89
ISSN: 0148-0227
Subject Category
Lunar And Planetary Exploration
Accession Number
85A17655
Funding Number(s)
CONTRACT_GRANT: NSG-9062
CONTRACT_GRANT: NSG-9056
CONTRACT_GRANT: NAGW-179
Distribution Limits
Public
Copyright
Other

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