In situ laser ablation ICP-MS analyses of dimict diogenites: Further evidence for harzburgitic and orthopyroxenitic lithologies
Article first published online: 28 MAY 2013
© The Meteoritical Society, 2013.
Meteoritics & Planetary Science
Volume 48, Issue 6, pages 1050–1059, June 2013
How to Cite
Beck, A. W., McSween, H. Y. and Bodnar, R. J. (2013), In situ laser ablation ICP-MS analyses of dimict diogenites: Further evidence for harzburgitic and orthopyroxenitic lithologies. Meteoritics & Planetary Science, 48: 1050–1059. doi: 10.1111/maps.12129
- Issue published online: 13 JUN 2013
- Article first published online: 28 MAY 2013
- Manuscript Accepted: 19 APR 2013
- Manuscript Received: 1 NOV 2011
- NASA Cosmochemistry Grant. Grant Number: NNG06GG36G
Trace element concentrations in pyroxene, plagioclase, and olivine were measured in five diogenite breccias previously identified as containing distinct harzburgitic (ol+opx) and orthopyroxenitic (opx) lithologies (dimict). Three samples show two distinct populations of pyroxene trace element abundances, supporting their classification as dimict. These three meteorites show increases in Y, Yb, and HREE concentrations from harzburgitic to orthopyroxenitic pyroxenes, supporting the hypothesis that the lithologies are related through fractional crystallization whereby harzburgite olivine and pyroxene crystallized from the magma first followed by orthopyroxenite pyroxene. Depletions in LREE and Eu concentrations in the orthopyroxenitic lithology are most likely due to equilibration with LREE and Eu-rich phases, likely plagioclase, which is found primarily in that lithology.
Two samples do not show evidence supporting a dimict classification. Large pyroxene trace element variation in one sample indicates that it is polymict, while uniform trace element distribution in the other suggests that it may be a monomict breccia.