MAC88105 - A regolith breccia from the lunar highlands: Mineralogical, petrological, and geochemical studies

Conference · Fri Nov 01 04:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (United States)

OSTI ID:5212002

Koeberl, C ^[1]; Kurat, G; Branstaetter, F ^[2]

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1. Univ. of Vienna, (Austria)
2. Naturhistorisches Museum, Vienna (Austria)

The new large lunar meteorite MAC88105 is a dense breccia, with lithic and mineral clasts and fragments set into a welded matrix. It is a regolith breccia which shows some recrystallization and evidence for a late shock event during which anorthositic glass veins were formed. Shock effects (most probably due to impact ejection from the moon) are present throughout the sample and require a shock pressure of about 25-30 GPa, in agreement with observations made on other lunar meteorites. The presence of devitrified glass (spheres and shards) supports a regolith origin. Most common are meta-meltbreccias consisting of abundant anorthitic plagioclase clasts and a dense, fine-grained matrix. Some fine-grained hornfelsic to granulitic metabreccias are also present. Lithic clast compositions are predominantly anorthositic noritic (or noritic anorthositic), and anorthositic troctolitic. The bulk comparison of MAC88105 is different from that of the lunar meteorites and suggests a different source, which is supported by cosmic-ray and noble gas data. At this time it seems likely that about four individual impact events have been responsible for delivering the seven highland meteorites.

• OSTI ID: 5212002
• Report Number(s): CONF-9003166--
• Conference Information: Journal Name: Geochimica et Cosmochimica Acta; (United States) Journal Volume: 55:11
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ANORTHOSITES
CHEMICAL COMPOSITION
ELEMENTS
GABBROS
GEOLOGIC HISTORY
GEOLOGY
IGNEOUS ROCKS
LUNAR MATERIALS
MATERIALS
METALS
METEORITES
MINERALOGY
MINERALS
ORIGIN
OXIDE MINERALS
OXYGEN COMPOUNDS
PETROGENESIS
PETROLOGY
PLUTONIC ROCKS
PYROXENES
RARE EARTHS
RECRYSTALLIZATION
ROCKS
SILICATES
SILICON COMPOUNDS
SPINELS