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Petrology of some lithic fragments from Luna 20

Geochimica et Cosmochimica Acta

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Abstract

Microscopic and electron microprobe studies were made of polished thin sections of part of a 30-mg sample of 250-500 ??m lunar soil returned by Luna 20 from a point between Mare Fecunditatis and Mare Crisium. Very fine-grained lithic (crystalline) rock fragments, composing about one fifth of the total sample, have mineralogical compositions equivalent to various types of gabbro, anorthositic gabbro, gabbroic anorthosite and troctolite, with minor basalt. The textures now observed in these fragments are in large part metamorphic. Twentyseven electron microprobe analyses of minerals from these fragments are presented, including olivine, plagioclase, pyroxene, spinel, nickel-iron and a Zr-Ti-REE mineral possibly similar to 'phase B' of Lovering and Wark (1971). Analyses of seven melt inclusions and twenty-eight defocused beam analyses of lithic fragments are also given. Some of the fragments contain 'gas' inclusions which, along with the fine grain size, are believed to indicate final crystallization under low pressure near surface conditions. The almost complete absence of granophyric material in this sample raises the question of whether or not there are at least two distinct magmas for the plagioclase-rich terrae rocks from which this soil sample was derived in part. ?? 1973.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Petrology of some lithic fragments from Luna 20
Series title:
Geochimica et Cosmochimica Acta
Volume
37
Issue:
4
Year Published:
1973
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geochimica et Cosmochimica Acta