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Rare earth patterns in shergottite phosphates and residuesLeaching experiments with 1M HCl on ALHA 77005 powder show that rare earth elements (REE) are concentrated in accessory phosphate phases (whitlockite, apatite) that govern the REE patterns of bulk shergottites. The REE patterns of whitlockite are typically light REE-depleted with a negative Eu anomaly and show a hump at the heavy REE side, while the REE pattern of apatite (in Shergotty) is light REE-enriched. Parent magmas are calculated from the modal compositions of residues of ALHA 77005, Shergotty, and EETA 79001. The parent magmas lack a Eu anomaly, indicating that plagioclase was a late-stage crystallizing phase and that it probably crystallized before the phosphates. The parent magmas of ALHA 77005 and Shergotty have similar REE patterns, with a subchondritic Nd/Sm ratio. However, the Sm/Nd isotopoics require a light REE-depleted source for ALHA 77005 (if the crystallization age is less than 600 Myr) and a light REE-enriched source for Shergotty. Distant Nd and Sr isotopic signatures may suggest different source regions for shergottites.
Document ID
19870046807
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Laul, J. C.
(Battelle Pacific Northwest Laboratories Richland, WA, United States)
Date Acquired
August 13, 2013
Publication Date
March 30, 1987
Publication Information
Publication: Journal of Geophysical Research
Volume: 92
ISSN: 0148-0227
Subject Category
Lunar And Planetary Exploration
Accession Number
87A34081
Funding Number(s)
CONTRACT_GRANT: NAS9-15357
Distribution Limits
Public
Copyright
Other

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