%0 Journal Article %1 LODDERS1993 %A LODDERS, K. %A FEGLEY, B. %D 1993 %J EARTH AND PLANETARY SCIENCE LETTERS %K ABUNDANCE; CHONDRITES; CONDENSATION; ELEMENTS; ENSTATITE FRACTIONATIONS; INCLUSION; JUPITER; METEORITES; ORIGIN; RARE-EARTH REFRACTORY SYSTEM %N 1-2 %P 125--145 %T LANTHANIDE AND ACTINIDE CHEMISTRY AT HIGH C/O RATIOS IN THE SOLAR NEBULA %V 117 %X Chemical equilibrium calculations were performed to study the condensation chemistry of the REE and actinides under the highly reducing conditions which are necessary for the formation of the enstatite chondrites 1,2. Our calculations confirm that the REE and actinides condensed into oldhamite (CaS), the major REE and actinide host phase in enstatite chondrites, at a carbon-oxygen (C/O) ratio greater-than-or-equal-to 1 in an otherwise solar gas. Five basic types of REE abundance patterns, several of which are analogous to REE abundance patterns observed in the Ca, Al-rich inclusions (CAIs) in carbonaceous chondrites, are predicted to occur in meteoritic oldhamites. All of the reported REE patterns in oldhamites in enstatite chondrites can be interpreted in terms of our condensation calculations. The observed patterns fall into 3 of the 5 predicted categories. The reported Th and U enrichments and ratios in meteoritic oldhamites are also consistent with predictions of the condensation calculations. Finally, pure REE sulfides are predicted to condense in the 10(-6) to 10(-9) bar range and may be found in enstatite chondrites if they formed in this pressure range.

@article{LODDERS1993, abstract = {Chemical equilibrium calculations were performed to study the condensation chemistry of the REE and actinides under the highly reducing conditions which are necessary for the formation of the enstatite chondrites [1,2]. Our calculations confirm that the REE and actinides condensed into oldhamite (CaS), the major REE and actinide host phase in enstatite chondrites, at a carbon-oxygen (C/O) ratio greater-than-or-equal-to 1 in an otherwise solar gas. Five basic types of REE abundance patterns, several of which are analogous to REE abundance patterns observed in the Ca, Al-rich inclusions (CAIs) in carbonaceous chondrites, are predicted to occur in meteoritic oldhamites. All of the reported REE patterns in oldhamites in enstatite chondrites can be interpreted in terms of our condensation calculations. The observed patterns fall into 3 of the 5 predicted categories. The reported Th and U enrichments and ratios in meteoritic oldhamites are also consistent with predictions of the condensation calculations. Finally, pure REE sulfides are predicted to condense in the 10(-6) to 10(-9) bar range and may be found in enstatite chondrites if they formed in this pressure range.}, added-at = {2009-11-03T20:21:25.000+0100}, author = {LODDERS, K. and FEGLEY, B.}, biburl = {https://www.bibsonomy.org/bibtex/2e8118ac811403189ab5c9cb73f7b2e2b/svance}, interhash = {c66fc7c98e4bc2fba156806cc81cd7c5}, intrahash = {e8118ac811403189ab5c9cb73f7b2e2b}, journal = {EARTH AND PLANETARY SCIENCE LETTERS}, keywords = {ABUNDANCE; CHONDRITES; CONDENSATION; ELEMENTS; ENSTATITE FRACTIONATIONS; INCLUSION; JUPITER; METEORITES; ORIGIN; RARE-EARTH REFRACTORY SYSTEM}, number = {1-2}, owner = {svance}, pages = {125--145}, timestamp = {2009-11-03T20:21:58.000+0100}, title = {LANTHANIDE AND ACTINIDE CHEMISTRY AT HIGH C/O RATIOS IN THE SOLAR NEBULA}, volume = 117, year = 1993 }