No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
AR-40-AR-39 dating of the meteorite Vetluga
... We report 40 Ar-39 Ar ages of individual feldspar crystals and rock clasts taken from specific lithologies within the meteorite. Published 40 Ar/ 39 Ar ages of Kapoeta and other HED meteorites (Kaneoka et al., 1979;Rajan et al., 1979;Shukolyukov et al., 1984;Caffee et al., 1985;Bogard, 1995;Kunz et al., 1997;Bogard and Garrison, 2003;Korochantseva et al., 2005;Shankar et al., 2008;Bogard and Garrison, 2009;Bogard, 2011;Cohen, 2013;Kennedy et al., 2013) lie between 3.1 and 4.5 Ga and are distributed as shown in Fig. 2. The prominent peak in the conventional data at approximately 3.7 Ga and the absence of ages younger than ∼3 Ga are striking. With one notable exception (Kaneoka et al., 1979), young (<1.3 Ga) 40 Ar/ 39 Ar have not been reported in bulk HED meteorites. ...
Kapoeta lithologies sampled as clasts are being systematically documented petrographically, chronologically, and isotopically by microsampling protocols to constrain in detail the history of the source regolith.
We report 40Ar/39Ar ages for several lithological components of the brecciated howardite Kapoeta and compare the ages with results for asteroid 4 Vesta as observed by the Dawn mission. Our Kapoeta sample has an unusual, millimeter wide glass vein that intruded into a complex breccia. The plateau ages of three lithic clasts of basaltic composition that were remote from the glass vein range from 4.2 to 4.5 Ga. Such ages are typical of eucritic material; the oldest reflects early magmatic crystallization ( ), the younger (4.2–4.5 Ga) reflect magmatism associated with protracted cooling. Samples of the glass vein itself, which include relict grains, give apparent ages between 3.1 and 3.9 Ga as do chips from the matrix. We consider both glass and bulk matrix ages as mixing ages; not marking the time of a single event, but dating regolith activity ( ).
ResearchGate has not been able to resolve any references for this publication.