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Glass Veins in the Unequilibrated Eucrite Yamato 82202The unequilibrated eucrite Yamato 82202 (Y82202) contains a network of glass veins, which are relatively thick (up to 1 mm in width) and are not devitrified. The host of the meteorite represents volcanic rock that crystallized >4.3 Gyr ago, probably as a lava flow on the surface of 4 Vesta. The impact event that formed the glass veins occurred at approx. 3.9 Gyr under conditions of low effective fo2 and very rapid cooling. A S-rich vapor probably was generated by impact vaporization of sulfides. The impact melt was not superheated and it retains some disordered structural characteristics of the original pyroxene and feldspar of the eucritic target lithology. The unequilibrated pyroxenes of this eucrite and the pristine character of the glass indicate that the meteorite experienced no significant metamorphism after initial crystallization. Hence, it was not buried to a significant depth or covered by a lava flow or hot layer of impact ejecta. The meteorite resided at a shallow level (though not at the surface) on 4 Vesta or on one of the vestoids until it was ejected and traveled to Earth, probably with other HED materials that have Ar-36 exposure ages of approx. 13 Myr.
Document ID
20050217237
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Bogard, Donald
(NASA Johnson Space Center Houston, TX, United States)
Buchanan, Paul
(National Inst. for Research Kaga, Japan)
Noguchi, T.
(National Inst. for Research Kaga, Japan)
Katavama, Ikuo
(Tokyo Inst. of Tech. Japan)
Date Acquired
August 23, 2013
Publication Date
January 1, 2004
Subject Category
Geophysics
Funding Number(s)
OTHER: 344-31-30-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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