Apollo 12 feldspathic basalts 12031, 12038, and 12072; petrology, comparison and interpretations

Conference · Mon Jan 01 00:00:00 EST 1979

OSTI ID:6153846

Beaty, E W; Hill, S M.R.; Albee, A L; Baldridge, W S

Modal and chemical data indicate that 12072, 12038, and 12031, the Apollo 12 feldspathic basalts, form a well-defined group which cannot be related to the other Apollo 12 rock types. 12072 contains phenocrysts of olivine and pigeonite and microphenocrysts of Cr-spinel set in a fine-grained, variolitic groundmass. 12038 is a medium-grained, equigranular basalt with a texture indicating it was multiply saturated. 12031 is a coarse-grained rock with granular to graphic intergrowths of pyroxene and plagioclase; it was also multiply saturated. Petrologic observations, as well as the bulk chemistry, are consistent with the interpretation that 12031 could be derived from 12072 through fractionation of Cr-spinel, olivine, and pigeonite, the observed phenocryst assemblage. 12038, however, contains more pigeonite, less olivine, three times as much Ca-phosphate minerals, one-fifth as much troilite, and much more sodic plagioclase than 12072. These differences indicate that 12038 must have come from a separate igneous body. Consideration of the bulk compositions indicates that neither 12072 and 12031 nor 12038 could have been derived from the Apollo 12 olivine, pigeonite, or ilmenite basalts by crystal--liquid fractionation. The general petrologic similarities between 12072, 12031, and the other Apollo 12 basalts suggests that they were produced in either the same or similar source regions. 12038, however, is petrologically and chemically unique, and is probably exotic to the Apollo 12 landing site.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6153846
• Report Number(s): LA-UR-79-1117; CONF-790476-2; TRN: 79-016251
• Resource Relation: Conference: Lunar science conference 10, Houston, TX, USA, 24 Apr 1979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
LUNAR MATERIALS
PETROLOGY
BASALT
CHEMICAL COMPOSITION
OLIVINES
PYROXENES
SOLAR SYSTEM EVOLUTION
ALKALINE EARTH METAL COMPOUNDS
GEOLOGY
IGNEOUS ROCKS
IRON COMPOUNDS
IRON SILICATES
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
MINERALS
OXYGEN COMPOUNDS
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640107* - Astrophysics & Cosmology- Planetary Phenomena