Other
Scientific paper
Jul 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992metic..27q.246k&link_type=abstract
Meteoritics, vol. 27, no. 3, volume 27, page 246
Other
5
Scientific paper
While it is widely believed that the minerals in aubrite breccias are of igneous origin (e.g., 1) bulk trace element abundances (e.g., 2) and the distribution of trace elements between phases (e.g., 3-5) are incompatible with an igneous genesis and strongly suggest a nebular origin (e.g., 6). Here we report trace element data on mineral phases in a unique rock fragment from the Bustee meteorite as well as with the N and Ti isotope compositions in osbornite. In the first characterization of Bustee, Story-Maskelyne (7) described a rock fragment consisting of oldhamite, enstatite, augite, and plagioclase in which he also first dicovered osbornite. The rock consists of large (2-3 mm) rounded oldhamite embedded in granular pyroxene (pictures given by 7 and 8). Osbornite is commonly included in oldhamite. Some metal (Si- and Cr-bearing) and a few grains of heideite and other rare sulfides are present. The REE abundances in selected minerals are shown in the figure. Surprisingly, all patterns are nearly flat. The oldhamite is strongly enriched in REE (see also 3-5) and has a positive Eu anomaly. Osbornite shows a slightly fractionated pattern with La>Lu and REE abundances of 0.5-9 x CI. Pyroxenes have the lowest REE contents at 0.2-0.3 x CI (pigeonite) and 0.03-0.08 x CI (enstatite). Isotopic compositions of Ti and N in osbornite and of Ca in oldhamite are indistinguishable from terrestrial. The distribution of REE beween mineral phases does not correspond to experimentally determined distribution coefficients (9). This and the primitive (not crystal-chemically controlled) REE abundances in all phases make it very likely that the minerals of the oldhamite-pyroxenite from Bustee were formed by condensation. The condensation sequence must have been osbornite-oldhamite- pigeonite-enstatite. As the first major phase to condense, oldhamite apparently scavenged most of the REE present in the gas. It must have been formed well below 1380 K (10) and from a slightly fractionated gas enriched in the volatile elements Eu and Yb. References: (1) OKADA A. et al. (1988) Meteoritics 23, 59-74; (2) WOLF R. et al. (1983) Geochim. Cosmochim. Acta 47, 2257-2270; (3) GRAHAM A.L. and HENDERSON P. (1985) Meteoritics 20, 141-149; (4) WHEELOCK M.M. et al. (1990) Lunar Planet. Sci. XXI, 1327- 1228; (5) FLOSS C. and CROZAZ G. (1991) Meteoritics 26, 334; (6) KURAT G. (1988) Phil. Trans. R. Soc. London A325, 459-482; (7) STORY-MASKELYNE N. (1870) Phil. Trans. R. Soc. London 160, 189-214; (8) FLIGHT W. (1875) Geolog. Mag. II, 400-412; (9) LODDERS K. and PALME H. (1990) Lunar Planet. Sci. XXI, 710- 711; (10)LODDERS K. and B. FEGLEY (1992) Lunar Planet. Sci. XXIII, 797-780; Figure 1, which in the hard copy appears here, shows normalized REE contents of some minerals in an oldhamite-pyroxenite from Bustee.
Brandstatter Frans
Kurat Gero
Zinner Emst
No associations
LandOfFree
An Ion Microprobe Study of a Unique Oldhamite-Pyroxenite Fragment from the Bustee Aubrite 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 An Ion Microprobe Study of a Unique Oldhamite-Pyroxenite Fragment from the Bustee Aubrite, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An Ion Microprobe Study of a Unique Oldhamite-Pyroxenite Fragment from the Bustee Aubrite will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1209527