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Rhodes, J. M.

Publications and source records attributed to Rhodes, J. M..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

A chemical model for lunar non-mare rocks

Nearly all rocks returned from the moon are readily divided into three broad categories on the basis of their chemical compositions: (1) mare basalts, (2) non-mare rocks of basaltic composition (KREEP, VHA), and (3) anorthositic rocks. Only mare basalts may unambiguously be considered to have original igneous textures and are widely understood to have an igneous origin. Nearly all other lunar rocks have lost their original textures during metamorphic and impact processes. It is shown that for these rocks one must work primarily with chemical data in order to recognize and define rock groups and their possible modes of origin. Non-mare rocks of basaltic composition have chemical compositions consistent with an origin by partial melting of the lunar interior. The simplest origin for rocks of anorthositic chemical composition is the crystallization and removal of ferromagnesian minerals. It is proposed that the rock groups of anorthositic and non-mare basaltic chemical composition could have been generated from a single series of original but not necessarily primitive lunar materials.

Hubbard, N. J.↗
NASA NTRS1974

The relationships between geology and soil chemistry at the Apollo 17 landing site

Within the wide compositional range of the Apollo 17 soils, three distinct chemical groups have been recognized, each one corresponding broadly with a major geological and physiographic unit. These groups are: (1) Valley Floor type soils, (2) South Massif type soils, and (3) North Massif type soils. The observed chemical variations within and between these three groups is interpreted by means of mixing models in terms of lateral transport and mixing of prevailing local rock types, such as high-titanium basalts, KREEP-like noritic breccias, anorthositic gabbro breccias and orange glass. According to these models, North Nassif types evolved on the lower slopes of the North Massif and Sculptured Hills where anorthositic gabbro predominates over noritic breccia and where lateral mixing with basalt is effective, whereas the South Massif type soils originally developed on the upper slopes of the South Massif, where anorthositic breccia and noritic breccias are equally abundant, and where lateral mixing with basalt was minimal.

Rhodes, J. M.↗
NASA NTRS1974

Chemical evidence for the origin of 76535 as a cumulate

Lunar sample 76535 is a coarse-grained troctolitic granulite. It is characterized by low REE concentrations and a positive Eu anomaly. Its original petrographic character has been disturbed by metamorphic reequilibration. Its chemical characteristics are those of an olivine-plagioclase cumulate. The amount of trapped parent liquid in the rock is estimated to be in the range of 8-16%. The REE concentrations of the parent liquid, if 16%, range from 13 times the chondritic value for Lu to 27 times for La. The parent liquid had no appreciable Eu anomaly.

Haskin, L. A.↗
NASA NTRS1973

Chemistry of lunar basalts with very high alumina contents.

A chemically distinct group of lunar rocks with the trace element characteristics of basaltic lunar rocks is apparently ubiquitous on the lunar surface. Such rocks have been found at the Apollo 15, Apollo 16, and Luna 20 landing sites. They may be derived from the plains-forming material that has been designated Cayley Formation.

Hubbard, N. J.↗
NASA NTRS1973

Lunar rock types - The role of plagioclase in non-mare and highland rock types

Some nonmare and highland rock types (14310 type KREEP and very high Al2O3 basalts) have the internal chemical variations expected for a plagioclase-liquid system. The observed Eu variations in these rock types suggest a D(Eu) 1/p of 0.6 to 0.7. The Sr variations suggest a D(Sr) 1/p of about 0.6, with values as low as 0.35 suggested for some materials from sample 14063. Common Apollo 14 KREEP and Apollo 15 KREEP do not show internal Sr, Eu, Al2O3 variations consistent with the D(Eu, Sr) 1/p values derived for 14310 type KREEP. Major element and experimental data indicate that olivine or pyroxene is a large, perhaps dominant, controller of chemical variations within common Apollo 14 KREEP. The application of these distribution coefficients to pure anorthosites like 15415 yields the model dependent conclusion that the silicate liquids with which such anorthosites may have been chemically equilibrated have not yet been analyzed and perhaps not directly sampled.

Hubbard, N. J.↗
NASA NTRS1972

The chemical composition of soil from the Apollo 16 and Luna 20 sites.

The concentrations of the rare earth elements K, Rb, Sr, Ba, U, Zr, and Cr for the Luna 20 soil and four different Apollo 16 soils are reported. These trace element abundances imply: (1) that the lunar highlands consist of a mixture of rocks rich in large ion lithophile (LIL) elements and LIL-element improverished anorthosites; or (2) that the bulk of the aluminum-rich crust did not originate by upward segregation of plagioclase in a primitive liquid shell. The Luna 20 soil is distinguished from the Apollo 16 soil by lower aluminum and LIL element abundances.

Bansal, B. M.↗
NASA NTRS1972

Chemical features of the Luna 16 regolith sample.

The Luna 16 regolith sample differs from Apollo 11, 12 and 14 regolith and basalt samples by having smaller negative Eu and Sr anomalies and nearly chondritic Eu/Sm and Eu/Sr ratios although the overall REE, Ba, Sr and U concentrations are 25 to 45 times chondrites. Major element data, in particular FeO vs Al2O3, show that the Luna 16 regolith sample is composed of materials that follow a quantitatively different Fe/Al variation than do Apollo 11, 12, 14 and 15 samples. The small Eu and Sr anomalies and the displaced Fe/Al variation are two chemical features unique to the Luna 16 regolith sample. The Luna 16 regolith sample can contain little if any of the rock types abundant at Apollo sites, thus indicating that the unique chemical features are typical of local or nearby materials and indicate a separate petrogenetic province for major component rock types of the Luna 16 regolith.

Hubbard, N. J.↗
NASA NTRS1972

Nonmare basalts. II.

Chemical characteristics of KREEP basalts from the Apollo 12 site are discussed. It is indicated that nonmare basalts are chemically distinct from mare basalts, primarily in FeO and Al2O3 concentrations and their ratios, and that the spectra of the former are closely related to the degree of partial melting. It is also noted that the chemical compositions of KREEP basalts from Apollo 12, 13, and 14 show very little chemical variation.

Hubbard, N. J.↗
NASA NTRS1965

Physiology

Physiological parameters recorded from chimpanzees before, during, and after rapid decompression to near vacuum - aerospace medicine

DECOMPRESSION↗