Elephant Moraine 87521: The first lunar meteorite composed of predominantly mare material
- Univ. of California, Los Angeles (USA)
The trace-element chemistry and detailed petrography of brecciated Antarctic meteorite EET87521 reveal that it is not, as originally classified, a eucrite. Its Fe/Mn ratio and bulk Co content are fair higher than expected for a eucrite. Only one known type of extraterrestrial material resembles EET87521 in all important respects for which constraints exist: very-low-Ti (VLT) lunar mare basalts. Even compared to VLT basalts, EET87521 is enriched in REE. However, other varieties of high-alumina, low-Ti mare basalt are known that contain REE at even higher concentrations than EET87521. Several clasts in EET87521 preserve clear vestiges of coarse-grained igneous, possibly orthocumulate, textures. Mineralogically, these coarse-grained clasts are diverse; e.g., olivine ranges from Fo{sub 15} in one to Fo{sub 67} in another. One clast with an anomalously fine-grained texture is anorthositic and contains exceptionally Mg-rich pyroxene and Na-poor plagioclase, along with the only FeNi-metal in the thin section. Its FeNi-metals have compositions typical of metals incorporated into lunar soils and polymict breccias as debris from metal-rich meteorites. However, the low Ni and Ir contents of our bulk-rock analysis imply that the proportion of impact-projectile matter in our chip sample is probably small. The moderate degree of lithologic diversity among the lithic lasts and the bulk composition in general indicate that EET87521 is dominated by a single rock type: VLT mare basalt.
- OSTI ID:
- 6712665
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Vol. 53:12; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
METEORITES
COSMOCHEMISTRY
MINERALOGY
ORIGIN
PETROGRAPHY
BASALT
COBALT
CONCENTRATION RATIO
ELEMENT ABUNDANCE
GEOLOGIC HISTORY
IRON
LUNAR MATERIALS
MANGANESE
ABUNDANCE
CHEMISTRY
ELEMENTS
IGNEOUS ROCKS
MATERIALS
METALS
ROCKS
TRANSITION ELEMENTS
VOLCANIC ROCKS
580000* - Geosciences
640106 - Astrophysics & Cosmology- Cosmology