Vestnik Otdelenia nauk o Zemle RAN VOL. 2, NZ6022, doi:10.2205/2010NZ000040, 2010

To question about origin of pallasites

Lavrenteva Z. A., A. YU. Lyul, G. M. Kolesov

Abstract

In the present paper the results of chemical abundances in olivine, metal, tridimite, troilite, daubreelite and 4 fragments from Omolon pallasite are reported. Six groups of olivines with different contents of Co and REE have been revealed. Olivine REE compositions show that pallasite olivine cannot be produced by single stage differentiation from the starting material with an unfractionated REE abundance pattern. Tridimite have HREE-enriched pattern. All fragments enriched in LREE, Na, Ca, Cs, Hf, Th and Ta. The simplest model to explain the observed REE pattern in pallasite minerals need two steps: the LREE and HREE-enriched phases ware removed at first and the olivine crystals ware formed as agglomerate later.

Received 28 April 2010; published 5 June 2010.