title: Heterogeneity in lunar anorthosite meteorites: implications for the lunar magma ocean model.
abstract: The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites: Dhofar 908 and Dhofar 081. The rare earth elements were present in abundances of approximately 0.1 to approximately 10× chondritic (CI) abundance. Every plagioclase exhibited a positive Eu-anomaly, with Eu abundances of up to approximately 20×CI. Calculations of the melt in equilibrium with anorthite show that it apparently crystallized from a magma that was unfractionated with respect to rare earth elements and ranged in abundance from 8 to 80×CI. Comparisons of our data with other lunar meteorites and Apollo samples suggest that there is notable heterogeneity in the trace element abundances of lunar anorthosites, suggesting these samples did not all crystallize from a common magma source. Compositional and isotopic data from other authors also suggest that lunar anorthosites are chemically heterogeneous and have a wide range of ages. These observations may support other models of crust formation on the Moon or suggest that there are complexities in the lunar magma ocean scenario to allow for multiple generations of anorthosite formation.
authors.affiliation: Natural History Museum, Cromwell Road, London SW7 5BD, UK sarr@nhm.ac.uk.
authors.forename: Sara S
authors.initials: SS
authors.lastname: Russell
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester M13 9PL, UK.
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Joy
authors.affiliation: Natural History Museum, Cromwell Road, London SW7 5BD, UK.
authors.forename: Teresa E
authors.initials: TE
authors.lastname: Jeffries
authors.affiliation: Specola Vaticana, V-00120, Vatican City State.
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Consolmagno
authors.affiliation: Natural History Museum, Cromwell Road, London SW7 5BD, UK.
authors.forename: Anton
authors.initials: A
authors.lastname: Kearsley
keywords: lunar evolution; lunar meteorites; magma ocean; rare earth elements
references.citation: Nature. 2011 Aug 17;477(7362):70-2
references.pmid: 21849974
references.citation: Philos Trans A Math Phys Eng Sci. 2014 Sep 13;372(2024):20130315
references.pmid: 25114318
references.citation: Nature. 2007 Dec 20;450(7173):1206-9
references.pmid: 18097403
references.citation: Philos Trans A Math Phys Eng Sci. 2014 Sep 13;372(2024):20130240
references.pmid: 25114310
references.citation: Science. 2013 Feb 8;339(6120):671-5
references.pmid: 23223394
references.citation: Philos Trans A Math Phys Eng Sci. 2014 Sep 13;372(2024):20130246
references.pmid: 25114305
references.citation: Science. 1970 Jan 30;167(3918):602-4
references.pmid: 17781512