Other
Scientific paper
Jul 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994metic..29q.475h&link_type=abstract
Meteoritics (ISSN 0026-1114), vol. 29, no. 4, p. 475
Other
3
Abundance, Chondrites, Meteoritic Composition, Rare Earth Elements, Anomalies, Cathodoluminescence, Ion Probes, Melts (Crystal Growth), Volatility
Scientific paper
Previous Rare Earth Elements (REE) analyses of unequilibrated enstatite chondrites (UECs) have shown that the REE patterns of enstatite grains tend to be mirror images of those of oldhamite, the major REE carrier in UECs. A detailed study of REE concentrations in Qingzhen (EH3) has also demonstrated that enstatites with red and blue cathodoluminescence (CL) have REE patterns that cannot be distinguished, and therefore these two types of enstatite must have been formed by similar processes, contrary to a suggested model. We have extended our ion microprobe study of enstatite to five UECs: Qingzhen (EH3), Yamato-691 (EH3), Indarch (EH4), MAC 88136 (EL3), and EET 90299 (EL3). The new and more extensive set of data confirms our previous conclusions. In addition to the negative Eu and Yb anomalies that characterize many enstatite grains, we also observed enstatite grains with a negative Sm anomaly that is always associated with a negative Yb anomaly. We analyzed both red and blue CL enstatite in chondrules as well as single grains. The absolute REE concentrations vary from measurement to measurement. However, there are no REE patterns or abundances that uniquely characterize either the CL color or the mode of occurrence of enstatite. Three REE patterns are commonly observed in both red and blue CL enstatite. In UECs, enstatite usually contains numerous tiny inclusions of albitic and sulfidic compositions. By monitoring the Ca and S signals throughout the measurements, we ascertained that the enstatite patterns were not due to the presence of oldhamite inclusions. Evaporative loss of Eu, Yb, and sometimes Sm during enstatite crystallization may be responsible for their depletions. Under the highly reducing conditions during formation of enstatite chondrites, Yb, Eu, and Sm (listed here in the order of decreasing volatility) are relatively volatile in comparison with the other REEs.
Crozaz Ghislaine
Hsu Weibiao
No associations
LandOfFree
REE concentrations and anomalies in the enstatite of unequilibrated enstatite chondrites 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 REE concentrations and anomalies in the enstatite of unequilibrated enstatite chondrites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and REE concentrations and anomalies in the enstatite of unequilibrated enstatite chondrites will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-822124