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Boynton, W. V.

Publications and source records attributed to Boynton, W. V..

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Composition of bulk samples and a possible pristine clast from Allan Hills A81005

Abundances of thirty-five elements were determined in two bulk samples and a white clast in the Allan Hills A81005 meteorite. High siderophile element content indicates that the sample is a regolith breccia. An Fe/Mn ratio of 77 in this meteorite eliminates parent bodies of known differentiated meteorites as the source of ALHA 81005. The incompatible elements are very similar to those found in most lunar highlands rocks, and provide very strong evidence that the sample is lunar in origin. The clast sample has the trace element pattern of a lunar anorthosite and is very low in KREEP and siderophile elements. It may be a fragment of a pristine lunar rock.

Boynton, W. V.↗
NASA NTRS1983

Lunar and Planetary Science Conference, 13th, Houston, TX, March 15-19, 1982, Proceedings. Part 2

The second part of the proceedings of the Thirteenth Lunar and Planetary Science Conference considers sedimentary processes and crustal cycling on Venus, a model for the formation of the earth's core, evidence of resurfacing in the lunar nearside highlands, the geology of Tethys, thermal stresses in planetary elastic lithospheres, the petrology and comparative thermal and mechanical histories of clasts in breccia 62236, lunar paleointensity data and its implications for the origin of lunar magnetism, and a model for the accumulation of solar wind radiation damage effects in lunar dust grains. Also discussed are fluid inclusions in stony meteorites, nuclear track and compositional studies of olivines in CI and CM chondrites, the impact of an asteroid or comet in the ocean and the extinction of terrestrial life, cooling rates for glass-containing lunar compositions, and the homogeneity of lava flows.

Boynton, W. V.↗
NASA NTRS1982

Lunar and Planetary Science Conference, 13th, Houston, TX, March 15-19, 1982, Proceedings. Part 1

The present conference on planetary and lunar science considers theoretical models for the composition of the Venus crust, the lunar crust, the prediction of phase relationships in planetary mantles, the volumetric analysis of complex lunar craters, grazing impacts on Mars, the determination of lunar structure by means of electrical conductivity and seismic experiments, results of studies on the Apollo 16 site rocks, as well as Apollo 14, 15 and 17 lunar glasses and regoliths, and carbon components and isotopic compositions of chondritic meteorites. Also discussed are iron meteorites, interplanetary dust and tektites, and such theoretical and experimental issues as refractory condensates and chondrules from solar furnace experiments, molecular synthesis through the irradiation of silicates, and the adsorption of excess fission Xe.

Boynton, W. V.↗
NASA NTRS1981

Superheavy elements - An early solar system upper limit for elements 107 to 110

The abundance of samarium-152 in the Santa Clara iron meteorite is found to be 108 x 10 to the 7th atoms per gram. This quantity, if attributed to fission of a superheavy element with atomic number 107 to 109, limits the amount of superheavy elements in the early solar system to 0.000017 times the abundance of uranium-238. For element 110, the limit is 0.000034.

Nozette, S.↗
NASA NTRS1979

Magnetite in CI carbonaceous meteorites - Origin by aqueous activity on a planetesimal surface

The composition and morphology of magnetite in CI carbonaceous meteorites appear incompatible with a nebular origin. Mineralization on the meteorite parent body is a more plausible mode of formation. The iodine-xenon age of this material therefore dates an episode of secondary mineralization on a planetesimal rather than the epoch of condensation in the primitive solar nebula.

Kerridge, J. F.↗
NASA NTRS1978

Fractionation in the solar nebula. II - Condensation of Th, U, Pu and Cm

Reasonable assumptions concerning activity coefficients allow the calculation of the relative volatility of the actinide elements under conditions expected during the early history of the solar system. Several of the light rare earths have volatilities similar to Pu and Cm and can be used as indicators of the degree of fractionation of these extinct elements. Uranium is considerably more volatile than either Pu or Cm, leading to fractionations of about a factor of 50 and 90 in the Pu/U and Cm/U ratio in the earliest condensates from the solar nebula. Ca,Al-rich inclusions from the Allende meteorite, including the coarse-grained inclusions, have a depletion of U relative to La of about a factor of three, suggesting that these inclusions may have been isolated from the nebular gas before condensation of U was complete. The inclusions, however, can be used to determine solar Pu/U and Cm/U ratios if the rare earth patterns are determined in addition to the other normal measurements.

Boynton, W. V.↗
NASA NTRS1978

The chaotic solar nebula - Evidence for episodic condensation in several distinct zones

Abundances of rare earth elements in Allende inclusions are considered along with the rim sequence on coarse-grained chondrules. It is found that in at least several zones the nebula went through episodes of condensation and gas/grain separation. Four separate zones are required to make the two types of fine-grained aggregates and the two types of coarse-grained chondrules. Other types of inclusions in Allende, such as the olivine aggregates, may well require additional condensation zones. All of these conclusions are based on data from one meteorite. Although the details of the gas/grain separation mechanism in these zones is not well understood, it is clear that a single monotonic-cooling condensation sequence followed by isolation of grains from gas cannot account for the observations.

Boynton, W. V.↗
NASA NTRS1977

Distribution of 28 elements in size fractions of lunar mare and highlands soils

Four volatile, six siderophile and 18 generally lithophile elements were determined in six sieve fractions of mare soil 15100 (moderately mature) and seven sieve fractions of highlands soil 66080 (highly mature). Previous work (Boynton et al., 1976) showed that the volatile elements in lunar soils were enriched in the finest size fraction relative to the coarsest factors by up to about 20. The present investigation tests Boynton's interpretation that the distribution pattern of the volatiles indicates the presence of two components: a volume-correlated component having volatile concentrations independent of grain size and a surface-correlated component with concentration increasing with decreasing grain size.

Boynton, W. V.↗
NASA NTRS1977

Genesis of howardites, diogenites, and eucrites

The reported investigation was mainly concerned with the precise determinations of major-, minor-, and trace-element abundances, especially the REE abundances in the bulk howardites in order to establish the bulk rock composition for the future chemical-mineralogical, petrographic studies of different rock types on the chemically unique howardites and diogenites if they exist. From the chemical data for the major-element abundances and the REE patterns of the howardites analyzed, it is evident that these howardites are predominantly composed of eucritic and diogenitic components. The analytical results for howardites and diogenites are shown in two tables together with the results for CRB-1. The chondritic normalized K, Sr, Ba, REE, Hf, and Sc abundances of these howardites are plotted in two graphs.

Fukuoka, T.↗
NASA NTRS1977

SCCRV, a major component of highlands rocks

An investigation was conducted of the composition of lunar highlands samples rich in mafics. Most of the samples were Apollo 16 rocks. The compositional data for 13 lunar rocks are listed in a table. The nonpristine rocks 64815 and 77545 having essentially identical KREEP contents of about 32% have very similar, high contents of the mafic component SCCRV. The same amounts of rather similar ingredients were mixed at locations 1000 km apart. The composition of SCCRV is discussed. According to the three most plausible hypotheses for the origin of SCCRV which are proposed the SCCRV is primordial material, SCCRV consists entirely or mainly of a single type of lunar rock, or SCCRV resulted from the mixing of two or more lunar materials.

Wasson, J. T.↗
NASA NTRS1977

Solar wind nitrogen - Mechanisms for isotopic evolution

Isotope systematics of nitrogen implanted in the lunar regolith indicate that the N-15/N-14 ratio at the source of the nitrogen has increased substantially with time. This source is most plausibly identified as the solar wind reservoir. However, rigorous testing of possible mechanisms for isotopic evolution of the solar convective zone shows that they all fail, by large factors, to explain the observed effect. Evolutionary processes on the lunar surface may be similarly eliminated, leaving the lunar nitrogen isotope anomaly currently unexplained.

Kerridge, J. F.↗
NASA NTRS1976

Chemical evidence for the genesis of the ureilites, the achondrite Chassigny and the nakhlites

An investigation has been conducted of the ureilites and the achondrite Chassigny to elucidate differences in their petrogenesis. The experimental studies reported include the determination of elemental abundances by instrumental neutron activation analysis. Attention is given to lithophile elements in ureilites, lithophile elements in Chassigny, the relationship between Chassigny and the nakhlites, and siderophile trace elements in the ureilites.

Boynton, W. V.↗
NASA NTRS1976

Rare earth element abundances in rocks and minerals from the Fiskenaesset Complex, West Greenland

The paper reports activation-analysis determinations of rare-earth-element (REE) and other trace-element concentrations in selected rocks, plagioclase, and mafic separates from the Fiskenaesset Complex. The REE abundances are found to be very low and atypical in comparison with other terrestrial anorthosites. The plagioclases are shown to be characterized by a deficiency in heavy RE elements relative to light ones and a positive Eu anomaly, while the mafic separates are enriched in heavy rare earths and have no Eu anomaly, except in one sample. It is found that the bulk and trace-element abundances of the plagioclases are similar to those observed in some lunar anorthosites, but the degree of Eu anomaly is less in the plagioclases. The data are taken as confirmation of the idea that fractionation processes were involved in the origin of the Complex, and it is concluded that the Complex may have been produced from a magma generated by partial melting of a garnet-bearing source.

Henderson, P.↗
NASA NTRS1976

Volatile compounds released during lunar lava fountaining

A modified radiochemical neutron activation analysis was used to determine 24 elements in three sieve separates and in HCl leach, HF etch, and residue fractions of the 500-62 micron separate of orange glass fines 74220. Six elements - In, Cd, Zn, Ga, Ge, and Au - were strongly concentrated in the leach, indicating that they were present as a surface deposit, probably a sublimate resulting from condensation of lava-fountain volatiles which expelled the orange glass onto the lunar surface.

Wasson, J. T.↗
NASA NTRS1976

Trace element evidence regarding a chondritic component in howardite meteorites

The concentrations of siderophiles Ni, Ge, Ru, Ir, and Au and volatiles Zn, Ga, Cd, and In in howardite meteorites were determined and are discussed along with similar data for eucrites and diogenites. The concentrations of the chondritic component in howardites are remarkably high. The concentrations in four high-siderophile howardites are comparable to those found in mature soils from the lunar highlands. The amounts of excess volatiles are roughly consistent with those expected if the chondritic component resemble CI, CM, or E4 chondrites. Evidence indicates that the howardite parent body had a radius of several hundred kilometers, and the most probable formation location was 1-2 AU from the sun.

Chou, C.-L.↗
NASA NTRS1975

Compositional evidence regarding the influx of interplanetary materials onto the lunar surface

Siderophilic element/Ir ratios are higher in mature lunar soils from highlands sites than in those from mare sites. It is suggested that the population of materials responsible for the early intense bombardment of the moon had high ratios and that the population responsible for the essentially constant flux has low ratios. Arguments are summarized against the viewpoint that the siderophiles in most highlands breccias originated in basin-forming projectiles. Differences in mature soil siderophile concentrations at the Apollo 14 and 16 sites indicate a substantially greater concentration at the latter site immediately following the Imbrium event. Siderophile concentrations are used to estimate mean regolith depths at the landing sites. The long-lived flux is calculated to be 2.9 g per cm per aeon averaged over the past 3.7 aeons. Consideration of the relationship between mass fluence and time indicates that the mass flux decreased with a half-life of about 40 million years immediately following the Imbrium event.

Wasson, J. T.↗