Rare earth element partitioning between minerals from anhydrous spinel peridotite xenoliths |
| |
| Authors: | Heinz-Günter Stosch |
| |
| Institution: | Mineralogisch-Petrographisches Institut der Universität zu Köln, Abteilung für Transzendentale Geochemie, Zülpicher Straβe 49, D-5000 Köln 1/West Germany |
| |
| Abstract: | REE abundances in minerals from spinel peridotite xenoliths from West Germany, the south-western U.S. and Mongolia decrease in the order clinopyroxene > orthopyroxene > olivine > spinel. While clinopyroxenes are similar in absolute chondrite-normalized concentrations to those known from other studies, orthopyroxenes and olivines are significantly lower in LREE although comparable in HREE. Spinels are much lower in all REE than any previously reported values and are completely negligible for the REE budget of peridotites.Partition coefficients for most orthopyroxene/clinopyroxene pairs increase systematically from La to Lu. Olivine/clinopyroxene and spinel/clinopyroxene partition coefficients increase from the intermediate rare earth elements to Lu and normally are higher for La compared to Sm.The application of Nagasawa's (1966) elastic lattice model suggests that all heavy but only minor amounts of the light REE substitute into structural positions of orthopyroxene and olivine.Significant differences between orthopyroxene/clinopyroxene partition coefficients for various xenoliths may be assigned to dependences upon equilibration temperature and bulk chemistry.Apart from grain surface contaminations, fluid inclusions which are practically always present in mantle minerals, can highly concentrate light rare earth elements and thus may be responsible for unexpectedly high concentrations of incompatible elements frequently reported for mantle olivines or orthopyroxenes. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
