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Impact melting of the Cachari eucrite 3.0 Gy agoThe chemical compositions and Ar-isotope gas-retention ages of host phase and glass veins in the Cachari eucrite are determined by microprobe and neutron-activation analysis and mass spectrometry, respectively. The results are presented in tables, graphs, and back-scattered electron images and characterized in detail. The compositions are found to support the thesis that the glass formed by shock melting of the host rock (or of rock having the same composition). The Ar-39/Ar-40 ages of host and glass are given as 3.04 + or - 0.07 Gyr and 3.47 + or - 0.04 Gyr, respectively; the former value is taken as the true data of melting, and the latter is attributed to incomplete postmelt degassing of Ar from the glass phase. The implications of the relative youth of this and other eucrites and howardites for the regolith history of the parent body are considered.
Document ID
19850054071
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bogard, D. D.
(NASA Johnson Space Center Houston, TX, United States)
Taylor, G. J.
(New Mexico Univ. Albuquerque, NM, United States)
Keil, K.
(New Mexico University Albuquerque, NM, United States)
Smith, M. R.
(Batelle Pacific Northwest Laboratories, Richland, WA; Oregon State University Corvallis, OR, United States)
Schmitt, R. A.
(Oregon State University Corvallis, OR, United States)
Date Acquired
August 12, 2013
Publication Date
April 1, 1985
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 49
ISSN: 0016-7037
Subject Category
Lunar And Planetary Exploration
Accession Number
85A36222
Funding Number(s)
CONTRACT_GRANT: NAG9-63
CONTRACT_GRANT: NAG9-30
Distribution Limits
Public
Copyright
Other

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