Ion Microprobe Determination of Rare Earth Elements in Perovskite from Kimberlites and Alnöites
| Autor: | Roger H. Mitchell, Stephen J. B. Reed |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Microprobe
010504 meteorology & atmospheric sciences Analytical chemistry Mineralogy Electron microprobe Fractionation 010502 geochemistry & geophysics 01 natural sciences law.invention Ion Igneous rock Geochemistry and Petrology law Mass spectrum Crystallization Geology 0105 earth and related environmental sciences Perovskite (structure) |
| Zdroj: | Mineralogical Magazine. 52:331-339 |
| ISSN: | 1471-8022 0026-461X |
| DOI: | 10.1180/minmag.1988.052.366.04 |
| Popis: | Ion microprobe analysis ofperovskite from kimberlites and alnöites permits the accurate determination of La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er and Yb at the part per million level. Other rare earth elements (REE) are subject to interferences in the mass spectrum caused by matrix-derived molecular ions and cannot easily be determined with comparable precision. Chondrite-normalized plots of the ion probe REE data are smooth curves, confirming the superiority of this technique over electron microprobe methods at the levels of REE abundance found in these perovskites. The perovskites analysed contain between 2.8 and 7.1 wt. % REE oxides and are highly enriched in the light REE, having La/Yb ratios of 577–3229. These La/Yb ratios are not representative of the parental magmas but result from REE fractionation during crystallization of the perovskite. Parental magma La/Yb ratios are estimated to be of the order of 120–650. The lower La/Yb ratios (80–200) found for whole-rock kimberlites are considered to result from contamination by relatively heavy REE-enriched crustal material. |
| Databáze: | OpenAIRE |
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