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At least 163 records · Page 9

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NASA NTRS1978

Trace element composition of Luna 24 Crisium VLT basalt

The origins of the individual particles analyzed from the Luna 24 core and the information they provide on the trace-element composition of Mare Crisium basalt are considered. Previous analyses of several Luna 24 soil fragments are reviewed. It is concluded that: (1) the average trace-element concentrations for 12 VLT basalt fragments are the best available estimates for bulk samples of Crisium VLT basalt; (2) there is weak evidence that the average Crisium basalt might have a small positive Eu anomaly relative to chondritic matter; (3) the soils contain components from sources other than the Crisium VLT basalt; and (4) there is no convincing information in concentrations of rare-earth elements, Co, Sc, FeO, or Na2O among the analyzed fragments to indicate more than one parent basalt.

Haskin, L. A.↗

NASA NTRS1978

Origin and history of the adcumulate eucrite, Moama as inferred from REE abundances, Sm-Nd and U-Pb systematics

The abundances of Sm-Nd and U-Pb isotopes and of rare earth elements (REE) in Moama cumulate eucrite were investigated. The Sm-Nd data plotted on a Nd-143/Nd-144 vs Sm-147/Nd-144 evolution diagram define a line with a slope corresponding to an age of 4.58 plus or minus 0.05 billion years and an initial Nd-143/Nd-144 ratio of about 0.50684. Moama was found to contain the lowest overall trivalent REE abundances, the most light REE-depleted abundance pattern, and largest positive Eu anomaly of any eucrite yet studied. The REE data indicate that Moama could have been derived by about 1 to 5% fractional crystallization from a liquid with REE contents similar to Juvinas, or about 20 to 30% fractional crystallization from a Sioux County-like liquid. The data are consistent with the hypothesis that the Moama, Serra de Mage, and Moore county cumulate meteorites could have been derived from the same parent liquid. Results of the U-Th-Pb study indicate that the majority of the Pb in Moama is of terrestrial origin, and suggest that the meteorite has undergone a minor thermal event causing re-equilibration of the U-Pb system.

Hamet, J.↗

NASA NTRS1978

Major and trace element chemistry of separated fragments from a hibonite-bearing Allende inclusion

The major and trace elements of separated fragments and a bulk sample from CG-11, a hibonite-bearing inclusion in the Allende meteorite, were analyzed. Major element abundances were used to determine the minerology of separated fragments. The high degree of correlation between Eu/Sm ratios and Lu/Yb ratios for the samples studied indicates that their rare earth element (REE) distributions are governed by two components. One, Lu-, Eu-rich, is probably hibonite; the other, depleted in these elements, seems to be associated with the secondary alteration phases, grossular, nepheline and anorthite. The REE distribution in CG-11 precludes melting events after formation of the secondary alteration phases, but a melting event involving the primary minerals cannot be excluded. The enrichment of Lu with respect to other measured REE in hibonite can be explained by present REE condensation models. Two Hf-bearing components, most likely hibonite and perovskite, are necessary to account for variations in Sc/Hf ratios in the fragments studied. The lithophile volatiles Na, Mn, Fe, Zn, and probably Cr increase in the same order as the amount of secondary alteration minerals; the volatile siderophile elements Co and Au, however, do not.

Davis, A. M.↗

NASA NTRS1979

Trace elements in the Allende meteorite. IV - Amoeboid olivine aggregates

INAA data for Ca, Sc, Hf, La, Ce, Sm, Eu, Tb, Yb, Lu, Os, Ir, Ru, Na, Cl, Br, Fe, Mn, Cr, Co, Au, As, and Sb are presented for ten amoeboid aggregates from the Allende meteorite. Only one lacks olivine. Seven of the remainder, as a group, have cosmic proportions of refractory lithophile and siderophile elements and appear to have formed when coarse-grained Allende inclusion material underwent partial reaction with a low-temperature nebular gas and mixture with FeO-rich olivine. The other two have highly fractionated abundances of refractory elements relative to one another compared to Cl chondrites, including Group II REE patterns, and probably formed by the mixing of fine-grained Allende inclusion material with FeO-rich olivine. Non-refractory siderophile components are also different in composition in each type of amoeboid olivine aggregate.

Grossman, L.↗

NASA NTRS1979

The LASL program in nuclear pumped liquid lasers

The development of nuclear-pumped, liquid-based lanthanide ion lasers is discussed. Early investigations of lanthanide ion lasers have lead to solid-state and gaseous neodymium lasers, and a demonstration of lasing in the liquid state. Solvents containing organic chelating agents have been employed in liquid Eu(+3) and Tb(+3) lasers to extend fluorescence lifetimes, however aprotic solvents have been found to enable the development of large-scale liquid lasers. The advantages to be gained from high-power nuclear-pumped lasers based on lanthanide solutions include the high density of fissile materials possible, and a nuclear pumping cell which can operate in either a nuclear or optical pumping mode is being fabricated at the Los Alamos Scientific Laboratory to investigate the nuclear pumping of liquid lanthanide ion lasers. Areas that need exploration before specific laser design features can be considered include energy channeling within the liquid upon excitation, radiation damage due to solvent dissociation, and reactor technology for the development of a self-critical liquid reactor.

Mansfield, C. R.↗

NASA NTRS1981

Earth's gravity field mapping requirements and concept

A future sensor is considered for mapping the Earth's gravity field to meet future scientific and practical requirements for earth and oceanic dynamics. These are approximately + or - 0.1 to 10 mgal over a block size of about 50 km and over land and an ocean geoid to 1 to 2 cm over a distance of about 50 km. To achieve these values requires a gravity gradiometer with a sensitivity of approximately 10 to the -4 power EU in a circular polar orbiting spacecraft with an orbital altitude ranging 160 km to 180 km.

Vonbun, F. O.↗

NASA NTRS1981

Foraging westward for pristine nonmare rocks - Complications for petrogenetic models

New advances are reported concerning an investigation which is being conducted to find and characterize more 'pristine' (compositionally endogenous) lunar rocks. Eleven nonmare samples are characterized petrographically and (except for two clasts that were prohibitively small) by chemical composition. The samples are assessed whether they are pristine on the basis of diagnostic features discussed by Warren and Wasson (1977). Five samples are found to be almost certainly pristine. They include the alkali-rich anorthosite 12073c, the troctolite 14179c, the anorthositic troctolite 14321c1, the troctolitic anorthosite 14321c2, and the anorthositic norite 15565c. Correlations between petrochemistry and longitude are also investigated, taking into account Eu fractionations, Sc-Ti-Sm fractionations, and Ca/Na-Mg/Fe fractionations.

Warren, P. H.↗

NASA NTRS1982

Complementary rare earth element patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the earth

Abundances of major, minor, and trace elements are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare earth element (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.

Ma, M.-S.↗

NASA NTRS1982

Iron metal production in silicate melts through the direct reduction of Fe/II/ by Ti/III/, Cr/II/, and Eu/II/

The production of metallic iron in silicate melts by chemical reactions of Ti(3+), Cr(2+), and Eu(2+) with Fe(2+) is demonstrated under experimental conditions in a simplified basaltic liquid. These reactions form a basis for interpreting the role of isochemical valency exchange models in explanations for the reduced nature of lunar basalts. The redox couples are individually investigated in the silicate melt to ascertain reference redox ratios that are independent of mutual interactions. These studies also provide calibrations of spectral absorptions of the Fe(2+) and Ti(2+) species in these glasses. Subsequent spectrophotometric analyses of Fe(2+) and Ti(2+) in glasses doped with both iron and titanium and of Fe(2+) in glasses doped with either iron and chromium or iron and europium ascertain the degree of mutual interactions in these dual-doped glasses.

Schreiber, H. D.↗

NASA NTRS1982

Comparative geochemistry of Apollo 16 surface soils and samples from cores 64002 and 60002 through 60007

New data are presented for the concentrations of 23 to 27 elements in nine Apollo 16 surface soil samples, two subsplits each of 12 splits of core 60002-7, and one subsplit each of 10 splits of drive tube 64002. The surface soils are generally similar to other surface soils collected at their respective stations. All ten 64002 samples are similar to each other and to the station 4 surface soils and distinctly different from soils at other stations. High iron concentrations previously reported for these same subsplits of 60002-7 result primarily from meteoritic metal. One sample from each core is contaminated by stainless steel. The recently proposed ferroan anorthositic norites are required to explain the soil compositions. A yet uncharacterized component with high concentrations of Na, Sr, and Eu is also needed.

Korotev, R. L.↗

NASA NTRS1983

A partially molten magma ocean model

Under the assumption that the outer 300-400 km of the moon was at first only partially, rather than fully molten, an explanation of the properties of the lunar crust and upper mantle is obtained according to which nuclei of anorthositic crust formed over localized bodies of magma segregated from the partial melt, and then grew peripherally until fully covering the moon. Over most of its growth period, the anorthosite crust floated on a layer of magma whose thickness was regulated by the opposing forces of (1) loss of material by fractional crystallization, and (2) addition of magma from the partial melt below. The clustering of Eu, Sr and Mg values found among pristine ferroan anorthosites are predicted by this model.

Shirley, D. N.↗

NASA NTRS1983

Sixth foray for pristine nonmare rocks and an assessment of the diversity of lunar anorthosites

A compositional and petrographic characterization of 11 nonmare samples shows five to be pristine, and four probably pristine. Five of the 11 are unique anorthosites that considerably extend the diversity of lunar anorthosites. Alkali anorthosites are rich in incompatible elements. The nature of the correlations between longitude and such parameters as Eu and Sm concentrations, and Sc/Sm, Ti/Sm, and Ca/Na ratios, has been elucidated for the case of the pristine samples because five are fro a western site (Apollo 14). The ratios determined for the ferroan anorthosite 14312c are close to normal, but significantly displaced in the direction of the nonferroan, western pristine rocks. This suggests that the composition-longitude relationships are as old as the late stages of the crystallization of the putative magma ocean.

Warren, P. H.↗

NASA NTRS1983

Average sedimentary rock rare Earth element patterns and crustal evolution: Some observations and implications from the 3800 Ma ISUA supracrustal belt, West Greenland

Rare earth element (REE) data is given on a set of clastic metasediments from the 3800 Ma Isua Supracrustal belt, West Greenland. Each of two units from the same sedimentary sequence has a distinctive REE pattern, but the average of these rocks bears a very strong resemblance to the REE pattern for the North American Shale Composite (NASC), and departs considerably from previous estimates of REE patterns in Archaean sediments. The possibility that the source area for the Isua sediments resembled that of the NASC is regarded as highly unlikely. However, REE patterns like that in the NASC may be produced by sedimentary recycling of material yielding patterns such as are found at Isua. The results lead to the following tentative conclusions: (1) The REE patterns for Isua Seq. B MBG indicate the existence of crustal materials with fractionated REE and negative Eu anomalies at 3800 Ma, (2) The average Seq. B REE pattern resembles that of the North American Shale Composite (NASC), (3) If the Seq. B average is truly representative of its crustal sources, then this early crust could have been extensively differentiated. In this regard, a proper understanding of the NASC pattern, and its relationship to post-Archaean crustal REE reservoirs, is essential, (4) The Isua results may represent a local effect.

Dymek, R. F.↗

NASA NTRS1984

Kinetics of the reaction HO2 + NO2 + M yields HO2NO2 + M

The flash photolysis/ultraviolet absorption technique was used to measure the rate constants for the reaction HO2 + NO2 + M yields HO2NO2 + M over the pressure range 50-700 torr and temperature range 229-362 K using He, O2, and N2 as diluent gases. The data were fit to the expression derived by Troe (1979) and co-workers for describing the pressure and temperature dependence of reactions in the falloff region. By combining these data with recent measurements of the rate constant for HO2NO2 thermal decomposition values of 73.8 + or - 2 eu for the standard entropy and -12.6 + or - kcal/mol for the standard enthalpy of formation of HO2NO2 were obtained. A significant enhancement in the rate constant was observed when water vapor was added to the system.

Sander, S. P.↗

NASA NTRS1985

Geochemical confirmation of the lunar magmasphere hypothesis

The lunar magmasphere (or magma ocean) hypothesis was originally conceived to account for the enrichment of cumulus plagioclase (Al and Ca) in the main (highlands) portion of the crust. The great age of the highlands, and the complementary pattern of Eu anomalies between the highlands and the younger mare basalts, helped convince most specialists that the magmasphere hypothesis is correct. Doubts persist, however, particularly among physicists concerned about heat sources. It was shown in 1976 that a plot of Na/Ca vs. Mg/Fe for pristine highlands cumulates manifests a profound bimodality: One group, the Mg-rich rocks, plots along a normal igneous trend of inverse correlation between Na/Ca and Mg/Fe; the other group, the ferroan anorthosites (FAN), features low Na/Ca and low Mg/Fe. Only the FAN group can be plausibly linked to plag. flotation over the magmasphere.

Warren, P. H.↗

NASA NTRS1985

Application of thermoluminescence for detection of cascade shower 1: Hardware and software of reader system

A reader system for the detection of cascade showers via luminescence induced by heating sensitive material (BaSO4:Eu) is developed. The reader system is composed of following six instruments: (1) heater, (2) light guide, (3) image intensifier, (4) CCD camera, (5) image processor, (6) microcomputer. The efficiency of these apparatuses and software application for image analysis is reported.

Akashi, M.↗

NASA NTRS1985

Spatial distribution read-out system for thermoluminescence sheets

A spatial distribution read-out system of thermoluminescence (TL) sheets is developed. This system consists of high gain image intensifier, a CCD-TV camera, a video image processor and a host computer. This system has been applied to artificial TL sheets (BaSO4:Eu doped) for detecting high energy electromagnetic shower and heavy nuclei tracks.

Yamamoto, I.↗

NASA NTRS1984

Chemical compositions of refractory inclusions in the Murchison C2 chondrite

Neutron activation has been used to analyze samples from ten refractory inclusions in Murchison for 36 elements. Two inclusions, BB-5 and MUCH-1, have large negative Yb anomalies unaccompanied by correspondingly large and negative Eu anomalies; six inclusions have group II or III patterns, or variants of such patterns. The frequency of highly fractionated REE patterns, and the absence of group I patterns, suggest that refractory inclusions in Murchison stopped equilibrating with the nebular gas at higher temperatures than most Allende coarse grained inclusions. Murchison inclusions tend to be lower in nonrefractory elements than Allende coarse grained inclusions, further suggesting that, on average, the former underwent less severe secondary alteration than the latter.

Ekambaram, V.↗