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Explosive volcanism and the compositions of cores of differentiated asteroidsEleven iron meteorite groups show correlations between Ni and siderophile trace elements that are predictable by distribution coefficients between liquid and solid metal in fractionally crystallizing metal magmas. These meteorites are interpreted to be fragments of the fractionally crystallized cores of eleven differentiated asteroids. Many of these groups crystallized from S-depleted magmas which we propose resulted from removal of the first partial melt (the Fe,Ni-FeS cotectic melt) by explosive pyroclastic volcanism of the type envisaged by Wilson and Keil (1991). We show that these dense, negatively buoyant melts can be driven to asteroidal surfaces due to the presence of excess pressure in the melt and the presence of buoyant bubbles of gas which decrease the density of the melt. We also show that, in typical asteroidal materials, veins will form which grow into dikes and serve as pathways for migration of melt and gas to asteroidal surfaces. Since cotectic Fe, Ni-FeS melt consists of about 85 wt pct FeS and 15 wt pct Fe, Ni, removal of small volumes of eutectic melts results in major loss of S but only minor loss of Fe,Ni, thus leaving sufficient Fe,Ni to form sizeable asteroidal cores.
Document ID
19930061592
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Keil, Klaus
(Hawaii Univ. Honolulu, United States)
Wilson, Lionel
(Hawaii Univ. Honolulu; Lancaster Univ., United Kingdom)
Date Acquired
August 16, 2013
Publication Date
May 1, 1993
Publication Information
Publication: Earth and Planetary Science Letters
Volume: 117
Issue: 2-Jan
ISSN: 0012-821X
Subject Category
Lunar And Planetary Exploration
Accession Number
93A45589
Funding Number(s)
CONTRACT_GRANT: NAGW-3281
CONTRACT_GRANT: NAG9-454
Distribution Limits
Public
Copyright
Other

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