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Published March 1973 | public
Book Section - Chapter

Experimental petrology and origin of rocks from the Descartes Highlands


Petrographic studies of Apollo 16 samples indicate that rocks 62295 and 68415 are crystallization products of highly aluminous melts. 60025 is a shocked, crushed and partially annealed plagioclase cumulate. 60315 is a recrystallized noritic breccia of disputed origin. 60335 is a feldspathic basalt filled with xenoliths and xenocrysts of anorthosite, breccia, and anorthite. The Fe/(Fe + Mg) of plagioclase appears to be a relative crystallization index. Low pressure melting experiments with controlled P_(o2) indicate that the igneous samples crystallized at oxygen fugacities well below the Fe/FeO buffer. Crystallization experiments.at various pressures suggest that the 62295 and 68415 compositions were produced by partial or complete melting of lunar crustal materials, and not by partial melting of the deep lunar interior.

Additional Information

© 1973 Pergamon Press. We have benefited from discussions with A. E. Bence, M. J. Drake, D. H. Lindsley, C. Simonds, G. J. Taylor, J. Warner, and R. J. Williams. We thank D. H. Green, I. Kushiro, and R. J. Williams for their careful and constructive critiques of the manuscript. Our electron probe is ably maintained by M. Campot. This study was supported by NASA grants NGR 22-007-175 and NGL 22-007-247 and the Harvard Committee on Experimental Geology and Geophysics.

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October 18, 2023