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At least 55 records · Page 3

Apollo 14 - Nature and origin of rock types in soil from the Fra Mauro formation.

Compositions of glasses in the Apollo 14 soil correspond to four types of Fra Mauro basalts, to mare basalts and soils, and, in minor amounts, to gabbroic anorthosite and potash granite. The Fra Mauro basalts can be related by simple low pressure crystal-liquid fractionation that implies a parent composition like that of Apollo 14 sample 14310.

Aitken, F. K.↗

Chemical compositions of some soils and rock types from the Apollo 15, 16, and 17 lunar sites

The major and minor element compositions of three Apollo 15 mare basalts, four Apollo 16 breccias, one soil, three Apollo 17 soils, one mare basalt, and one breccia have been determined by semimicro combined atomic absorption and colorimetric spectrophotometries. A discussion regarding analysis of small subsamples of coarse-grained lunar materials, such as certain Apollo 15 and 17 basalts, is given in which the suggestion is made that analytical methods designed to determine the bulk 'representative' chemical composition as well as the presence and extent of specimen heterogeneity are fundamentally necessary for a more complete understanding of genesis and history of lunar materials.

Nava, D. F.↗

Very low Ti /VLT/ basalts - A new mare rock type from the Apollo 17 drill core

Phaneritic fragments, vitrophyres, and glass beads of a new very low Ti (VLT) mare basalt are found in the Apollo 17 drill core. VLT lithic fragments are characterized by TiO2 content of approximately 0.5%, Mg/(Mg + Fe) of approximately 0.52, CaO/Al2O3 of approximately 0.9, and low alkali content. Although mineral systematics and modal composition of VLT basalt are similar to Apollo 12 and 15 low Ti basalts, VLT basalts cannot be related to these mare basalts by crystal fractionation. Since VLT basalt is isochemical with some of the less mafic green glasses, fractionation of VLT magma from a liquid of green-glass composition is a possibility. Spectral reflectance studies suggest that VLT-type basalts may be relatively common in mare basins.

Vaniman, D. T.↗

HCMM imagery for the discrimination of rock types, the detection of geothermal energy sources and the assessment of soil moisture content in western Queensland and adjacent parts of New South Wales and South Australia

Only photographic prints and negative films of day-visible, day-IR and night-IR imagery were received. For northwest Queensland, only five day-visible and day-IR frames of acceptable quality were received. A master-grid was established over these frames within which selected grid sections are being enlarged photographically for the identification of stream courses and geological features permitting an interpretation of the imagery relative to ground truth information. The imagery is also being scanned and digitized using a Joyce-Loebl microdensitometer for classification purposes. For areas for which good quality HCMM imagery is available, valuable information is obtained on ephemeral and seasonal drainage systems. The day-IR cover is particularly helpful.

Cole, M. M.↗

Geobotanical discrimination of ultramafic parent materials An evaluation of remote sensing techniques

Color and color infrared aerial photography and imagery acquired from a Daedalus DEI-1260 multispectral airborne scanner were employed in an investigation to discriminate ultramafic rock types in a test site in southwest Oregon. An analysis of the relationships between vegetation characteristics and parent materials was performed using a vegetation classification and map developed for the project, lithologic information derived from published geologic maps of the region, and terrain information gathered in the field. Several analytical methods, including visual image analysis, band ratioing, principal components analysis, and contrast enhancement and subsequent color composite generation were used in the investigation. There was a close correspondence between vegetation types and major rock types. These were readily discriminated by the remote sensing techniques. It was found that ultramafic rock types were separable from non-ultramafic rock types and serpentine was distinguishable from non-serpentinized peridotite. Further investigations involving spectroradiometric and digital classification techniques are being performed to further identify rock types and to discriminate chromium and nickel-bearing rock types.

Mouat, D. A.↗

Mixing levels, the Apennine Front soil component, and compositional trends in the Apollo 15 soils

New compositional data (by INAA) for 29 samples of Apollo 15 soil fractions are presented along with data for six depth intervals of the bottom half of the double drive tube at station 2 on the Apennine Front. The compositional trends in the Apollo 15 soils are discussed in terms of four techniques used to determine the important components of the regolith: graphical techniques, factor analysis, chemical analysis of individual soil particles, and mixing models. The concept of 'mixing levels' is introduced, which states that a sample of lunar regolith can be considered as a mixture on several different compositional levels (I, igneous rock types; II, local rock types; III, soils), and it is shown that most attempts at modeling lunar soils as mixtures have been directed at level II. It is argued that only four components are required to account for the variation in concentrations of lithophile elements in the Apollo 15 samples: mare basalt, KREEP basalt, green glass, and Apennine front soil (best represented by the station 2 samples).

Korotev, Randy L.↗

Lithologic Distribution and Geologic History of the Apollo 17 Site: The Record in Soils and Small Rock Particles from the Highland Massifs

Through analysis by instrumental neutron activation (INAA) of 789 individual lithic fragments from the 2 mm-4 mm grain-size fractions of five Apollo 17 soil samples (72443, 72503, 73243, 76283, and 76503) and petrographic examination of a subset, we have determined the diversity and proportions of rock types recorded within soils from the highland massifs. The distribution of rock types at the site, as recorded by lithic fragments in the soils, is an alternative to the distribution inferred from the limited number of large rock samples. The compositions and proportions of 2 mm-4 mm fragments provide a bridge between compositions of less than 1 mm fines and types and proportions of rocks observed in large collected breccias and their clasts. The 2 mm-4 mm fraction of soil from South Massif, represented by an unbiased set of lithic fragments from station-2 samples 72443 and 72503, consists of 71% noritic impact-melt breccia, 7% Incompatible-Trace-Element-(ITE)-poor highland rock types (mainly granulitic breccias), 19% agglutinates and regolith breccias, 1% high-Ti mare basalt, and 2% others (very-low-Ti (VLT) basalt, monzogabbro breccia, and metal). In contrast, the 2 mm - 4 mm fraction of a soil from the North Massif, represented by an unbiased set of lithic fragments from station-6 sample 76503, has a greater proportion of ITE-poor highland rock types and mare-basalt fragments: it consists of 29% ITE-poor highland rock types (mainly granulitic breccias and troctolitic anorthosite), 25% impact-melt breccia, 13% high-Ti mare basalt, 31 % agglutinates and regolith breccias, 1% orange glass and related breccia, and 1% others. Based on a comparison of mass- weighted mean compositions of the lithic fragments with compositions of soil fines from all Apollo 17 highland stations, differences between the station-2 and station-6 samples are representative of differences between available samples from the two massifs. From the distribution of different rock types and their compositions, we conclude the following: (1) North-Massif and South-Massif soil samples differ significantly in types and proportions of ITE-poor highland components and ITE-rich impact-melt-breccia components. These differences reflect crudely layered massifs and known local geology. The greater percentage of impact-melt breccia in the South- Massif light-mantle soil stems from derivation of the light mantle from the top of the massif, which apparently is richer in noritic impact-melt breccia than are lower parts of the massifs. (2) At station 2, the 2 mm-4 mm grain-size fraction is enriched in impact-melt breccias compared to the less than 1 mm fraction, suggesting that the <1 mm fraction within the light mantle has a greater proportion of lithologies such as granulitic breccias which are more prevalent lower in the massifs and which we infer to be older (pre-basin) highland components. (3) Soil from station 6, North Massif, contains magnesian troctolitic anorthosite, which is a component that is rare in station-2 South-Massif,contains magnesian troctolitic in impact-melt breccia interpreted by most investigators to be ejecta from the Serenitatis basin.

Jolliff, Bradley L.↗