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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Petrology of Luna 20 regolith from the lunar highlands.

The Luna 20 regolith sample contains crystalline lithic fragments of mare basalt, the anorthosite-norite-troctolite group, and feldspathic basalt. Discrete mineral fragments and mineral fragments in regolith breccias can generally be assigned, based on chemical criteria, to one or the other of the first two rock types. A complex history is indicated for the regolith fragments involving repeated metamorphism and melting of the highlands due to impact events. The glass fragments and the feldspathic basalts probably are the result of this melting and their composition may be representative of a large portion of the regolith at this site.

Crawford, M. L.↗
NASA NTRS1973

Luna 20 - Mineralogy and petrology of fragments less than 125-micron size.

Two milligrams of less than 125-micron size particles from the Luna 20 soil sample (22001,17) have been examined. The results of the mineral identification and analysis verify earlier assumptions that the nature of the lunar highlands is predominantly anorthositic in composition. The presence of highly magnesian clinopyroxene, orthopyroxene, and olivine suggests crystallization of highland rocks in an ultrabasic environment. No fragments were observed that could be unequivocally assigned to mare basalt types.

Meyer, H. O. A.↗
NASA NTRS1973

Petrology of some lithic fragments from Luna 20.

Microscopic and electron microprobe studies were made of polished thin sections of part of a 30-mg sample of 250- to 500-micron 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. Twenty-seven 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 28 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.

Roedder, E.↗
NASA NTRS1973

Apollo 16 rocks - Petrology and classification.

The Apollo 16 rocks are classified in three broad intergradational groups: (1) crystalline rocks, subdivided into igneous rocks and metaclastic rocks, (2) glass, and (3) breccias, which are subdivided into five groups on the basis of clast and matrix colors. Most of the rocks were derived by impact brecciation of an anorthosite-norite suite but may represent ejecta from more than one major basin. First-cycle breccias are believed to have consisted of clasts of crushed anorthosite-norite in a fine-grained partly fused matrix with a chemical composition similar to that of the clasts. Most of the other recognized breccia types could have been produced by rebrecciation of first-cycle breccias.

Wilshire, H. G.↗
NASA NTRS1974

Petrology

Boulder 1 as a whole can be considered a complex polymict breccia consisting of lithic and breccia clasts seated in a matrix that ranges from friable and poorly sintered to densely welded. Only two of the four samples collected from boulder 1, Station 2 have been examined in detail: 72255 and 72275. Of the remaining two, only two undocumented thin sections from 72235 have been studied, while none from 72215 has been examined. Sample 72275 was collected as representative of the boulder matrix, whereas the other three samples were thought to be large clasts.

Stoeser, D. B.↗
NASA NTRS1974

Lunar petrology conference

Papers delivered at the conference, held in July, 1973, in Houston, are reviewed. The prominent topics include the recognition of primary highland rock types, the nature of lunar breccias, the calculation of mineral equilibration in breccias as a temperature-time function, the nature of lunar regolith, a classification of mare basalts based on composition and texture, and current theories of origin of mare basalts. An attempt to evaluate the relation between the earliest period of lunar evolution and the available lunar data is also noted.

Ridley, W. I.↗
NASA NTRS1973

Composition, mineralogy, and petrology of 28 mare basalts from Apollo 15 rake samples

Twenty-eight mare basalts from three Apollo 15 rake sample sections are divided into five rock groups which are considered to represent at least five rock units. Three of these groups (pyroxene-phyric basalt, olivine-phyric basalt, and olivine microgabbro) are from the mare area and are probably near-surface local mare rock units. The remaining groups (feldspathic peridotite and feldspathic microgabbro) are found outside the mare, in Spur Crater at the foot of the Apennines; they may come from deeper levels of the local mare or from a more distant source.

Dowty, E.↗
NASA NTRS1973

The petrology of 76055,10, a thermally metamorphosed fragment-laden olivine micronorite hornfels

General petrographic description of a large regolith specimen collected at the Taurus-Littrow landing site of Apollo 17. The specimen consists of a large clast of olivine micronorite hornfels with well-devepoled porphyroblastic texture, surrounded by highly vesicular olivine micronorite hornfels with incipient development of the porphyroblastic textures. Pink spinels with radial anorthite rims occur in both the clast and the surrounding matrix.

Chao, E. C. T.↗
NASA NTRS1973

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 Po2 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.

Walker, D.↗
NASA NTRS1973

Petrology of Apollo 16 lunar highland rocks

Four lunar highland rocks collected by the Apollo 16 astronauts were studied both optically and with the electron microscope. The compositions of cataclastic anorthosite 60025,132, feldspathic basalt 68416,78, spinel troctolite 62295,68, and recrystallized breccia 60315,62 are discussed and graphically presented. Melting experiments were carried out on troctolite 62295,49 and felspathic basalt 68416,21 at temperatures from 1,220 to 1375 C and at pressures from 5 to 12 kb. Hypotheses concerning their petrogenesis are presented.

Hodges, F. N.↗