Other
Scientific paper
Jul 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992metic..27s.250l&link_type=abstract
Meteoritics, vol. 27, no. 3, volume 27, page 250
Other
3
Scientific paper
As part of our ongoing project on HED meteorites we have begun a study of several Russian eucrites and howardites in collaboration with Michael Nazarov of the Vernadsky Institute in Moscow. We report here the results of our INAA analyses of whole rock and eucritic clasts from eucrites Chervony Kut, Padvarninkai and Vetluga, and howardites Erevan, Yurtuk, and Zmenj. Dr. Nazarov is studying the petrography of these samples. Eucrites and Eucritic Clasts. Chervony Kut is an extremely coarse-grained eucrite, with an estimated average grain size of ~3 mm. The Vernadsky sample is a typical Juvinas group eucrite with Ca, Na, Fe, Sc, Cr, Co and incompatible trace elements (ITE) indistinguishable from the Juvinas group average. Another sample of the meteorite obtained from L. Nyquist appears to be unrepresentative of the whole rock. The very low Ca, Na, and Eu, high Fe, Sc, and Cr, and slightly high ITE suggest that this split is enriched in pyroxene and depleted in plagioclase. Our Padvarninkai clast and whole rock samples are identical within limits of analyses and sample heterogeneity, and are very similar in composition to Juvinas group eucrites. The meteorite is highly shocked and contains some maskelynite and glass veins, and as such has been compared to shergottites, but the composition is clearly that of a typical eucrite. Vetluga appears to be a more unusual eucrite. The meteorite is a light gray breccia with abundant basaltic clasts. Both whole rock and analyzed clast have Fe and Sc slightly higher than Juvinas group eucrites, and have slight negative Eu anomalies (CI normalized Eu/Sm of 0.89 and 0.80, respectively). Vetluga appears to be intermediate between Juvinas group eucrites and Nuevo Laredo and Lakagaon, and hence, may be a residual liquid. Cumulate Eucrites. Two of the clast samples appear to be cumulate eucrites. The Erevan clast was coarse-grained and has extremely low Na and ITE concentrations. La and Sm concentrations are only 5% and 1.4%, respectively; those of normal eucrites and HREE are below the detection limits. The Eu/Sm ratio is about twice that typical of cumulate eucrites, but both Fe and Ca concentrations are within the range of cumulate eucrites. The Yurtuk clast was received as debris. The presence of one ~4-mm plagioclase fragment suggests that the clast is relatively coarse-grained. The sample may not be representative of the original rock as we estimated that there was only ~20% pyroxene in the debris, much less than in cumulate eucrites. This is borne out by our analyses: Ca is atypically high and Fe and Sc are atypically low for cumulate eucrites. The REE pattern is flat at about 10% that of normal eucrites, except for a positive Eu anomaly, and appears to be that of a plagioclase-rich cumulate eucrite. Whole Rock Howardites. Whole rock samples of Erevan, Yurtuk, and Zmenj are typical howardites with compositions intermediate between eucrites and diogenites. Compared to typical eucrites, they have low Ca, Fe, and Sc, and high Cr. Based on Ca content, Erevan, Yurtuk, and Zmenj are estimated to contain approximately 67%, 55%, and 46% basaltic component, respectively. High concentrations of siderophile elements, Co (14-34 micrograms/g), Ni (30-200 micrograms/g) and Ir (up to 3 ng/g), are evidence for a chondritic component of up to 2% in the breccias. This geochemical study of six Russian eucrites and howardites has shown that most are fairly typical HED meteorites, but has identified two cumulate eucrite clasts and shown that Vetluga may be intermediate in composition between typical and evolved eucrites.
Lindström Markus
Mittlefehldt Dave W.
No associations
LandOfFree
A Geochemical Study of Russian Eucrites and Howardites does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Geochemical Study of Russian Eucrites and Howardites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Geochemical Study of Russian Eucrites and Howardites will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1210096