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At least 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Infrared and Raman spectroscopic studies of structural variations in minerals from Apollo 11, 12, 14 and 15 samples, volume 3

Infrared and Raman vibrational spectroscopic data, yielding direct information on molecular structure, were obtained for single grains ( 150 microns) of minerals, basalts, and glasses isolated from Apollo 11, 12, 14, and 15 rock and dust samples, and for grains in Apollo 14 polished butt samples. From the vibrational data, specification substitutions were determined for the predominant silicate minerals of plagioclase, pyroxene, and olivine. Unique spectral variations for grains of K-feldspar, orthopyroxene, pyroxenoid, and ilmenite were observed to exceed the ranges of terrestrial samples, and these variations may be correlatable with formation histories. Alpha-quartz was isolated as pure single grains, in granitic grains composited with sanidine, and in unique grains that were intimately mixed with varying amounts of glass. Accessory minerals of chromite and ulvospinel were isolated as pure grains and structurally characterized from their distinctive infrared spectra. Fundamental vibrations of the SiO4 tetrahedra in silicate minerals were used to classify bulk compositions in dust sieved fractions, basalt grains and glass particles, and to compare modal characteristics for maria, highland and rille samples. No hydrated minerals were found in any of the samples studied, indicating anhydrous formation conditions.

Estep, P. A.↗
NASA NTRS1972

Quantitative micro-luminescence and related studies of fine and/or glassy lunar surface materials

Papers on Raman and soft X-ray spectroscopy of lunar glasses and electron microscopy of lunar fines are presented. Individual particles of glasses from Apollo 11, 12, 14, and 15 samples were analyzed separately. Silicon emission shifts vary between parent rock types and can be interpreted as a range of Si-O distances from 1.612 to 1.637 A. Aluminum emission shifts relate to the amount of 4- and 6-coordinated Al in the glass. Raman spectra show broadened bands. Certain bands recur in many specimens and relate to the main normative minerals for the glass bulk composition, olivine, pyroxene, and anorthite. Quantitative size and shape analyses were carried out on six Apollo 14 and 15 samples of fines by computer evaluation of scanning electron microspace images. For the size range of 0.50 to 30 micron diameter, the distributions are log-normal on a number count basis. Aspect ratios range from 0.1 to 1.0 with an average value of about 0.6. The aspect ratios and a shape complexity factor vary only slightly among the samples.

Roy, R.↗
NASA NTRS1971

Contributions to Astrogeology: Geology of the lunar crater volcanic field, Nye County, Nevada

The Lunar Crater volcanic field in east-central Nevada includes cinder cones, maars, and basalt flows of probably Quaternary age that individually and as a group resemble some features on the moon. Three episodes of volcanism are separated by intervals of relative dormancy and erosion. Changes in morphology of cinder cones, degree of weathering, and superposition of associated basalt flows provide a basis for determining the relative ages of the cones. A method has been devised whereby cone heights, base radii, and angles of slope are used to determine semiquantitatively the age relationships of some cinder cones. Structural studies show that cone and crater chains and their associated lava flows developed along fissures and normal faults produced by tensional stress. The petrography of the basalts and pyroclastics suggests magmatic differentiation at depth which produced interbedded subalkaline basalts, alkali-olivine basalts, and basanitoids. The youngest flows in the field are basanitoids.

Scott, D. H.↗
NASA NTRS1971

Subsolidus reduction of lunar spinels.

Discussion of evidence that some lunar basalts must have exceeded the lower limit of crystallization oxygen fugacity (fO2) by several orders of magnitude. The evidence is based primarily on the decomposition of Cr-Al-ulvospinel, and is further supported in one case by the decomposition of olivine. The data suggest that some rocks have undergone intense nonequilibrium subsolidus reduction. The reduction phenomenon is widespread, and is considered to have developed either during initial deuteric cooling or as a result of a postcrystallization reduction event.

Haggerty, S. E.↗
NASA NTRS1972

Oxygen isotope temperatures of 'equilibrated' ordinary chondrites.

Measurements have been made of O-18/O-16 ratios of coexisting minerals (plagioclase, pyroxene, olivine) from nine ordinary chondrites. The O-18 content of a given mineral increases systematically from H through L to LL group. Isotope fractionations for mineral pairs fall on a concordancy line, suggesting that these minerals were crystallized in oxygen isotope equilibrium. The isotopic temperature is estimated to be 950 (plus or minus 100) C for seven of the type 5 and type 6 chondrites.

Onuma, N.↗
NASA NTRS1972

Infrared spectral emittance in geological mapping - Airborne spectrometer data from Pisgah Crater, California.

Measurements of spectral emittance in the IR region from 6.8 to 13.3 microns were made with an airborne spectrometer on flights at 650 m above the olivine basalt flows at Pisgah Crater in the southern Californian desert. Readings were taken at a rate of six spectra per second. The spectra show chemical and mineralogical differences that can be related to differences in the terrain below the aircraft.

Lyon, R. J. P.↗
NASA NTRS1972

Microprobe studies of three Luna 16 basalt fragments.

Three small fragments of Luna 16 basalt (NASA sample designation G38) have been analyzed with an electron microprobe. The mineralogy is generally similar to that found in Apollo 11 and 12 igneous rocks: major amounts of clinopyroxene, plagioclase, ilmenite and olivine; accessory spinel, troilite, Fe metal and residual phases. Unlike some Apollo 12 basalts, there is continuous zoning with no composition gap in the G38 spinels. Plagioclase analyses follow the same nonstoichiometric trends previously found in Apollo 11 and 12. The samples indicate a magmatic history (rapid crystallization from reduced melts) similar to that inferred from studies of Apollo 11 and 12 basalts.

Grieve, R. A. F.↗
NASA NTRS1972

Petrology of a portion of the Mare Fecunditatis regolith.

Extensive microprobe analyses have been made of pyroxenes, plagioclases, olivines, opaque minerals, and glasses in two 0.025 g lunar samples returned from the Luna 16 mission, with the aim to characterize the Mare Fecunditatis regolith. No major differences were found between the near surface soil horizon A and horizon D at approximately 30 cm depth. Resulting characteristics of the mineral examined are presented and discussed.

Jakes, P.↗
NASA NTRS1972

Luna 16 sample G36 - Another crystalline product of an extremely mafic magma.

Luna 16 sample G36 is a microbasalt containing skeletal olivine, plagioclase, ilmenite, and interstitial pyroxene. It apparently resulted from very rapid crystallization of a highly fractionated, totally liquid mafic magma. Although different in many details, G36 is generally similar to the ferromagnesian-rich Apollo 11 and 12 basalts. In this respect, it emphasizes the continuing problem of identifying a process on the moon which generated highly mafic magmas.

Hollister, L. S.↗
NASA NTRS1972

Mineral and bulk compositions of three fragments from Luna 16.

Electron microprobe analyses of fragment G37 show that it is a mare basalt with high aluminum and low magnesium content. Detailed analyses are given of olivine, pyroxene, ilmenite, ulvospinel and plagioclase. Fragment G46 is a cinder with bulk composition fairly similar to G37. Fragment G51 is entirely composed of plagioclase, An(93-96), with low contents of minor elements.

Steele, I. M.↗
NASA NTRS1972

Lunar properties from transient and steady magnetic field measurements.

The electrical conductivity of the lunar interior has been determined from magnetic field step transients measured on the lunar dark side. The simplest model which best fits the data is a spherically symmetric three layer model having a nonconducting outer crust, an intermediate layer with electrical conductivity of .00035 mhos/m, and an inner core with conductivity of .01 mhos/m. Temperatures calculated from these conductivities in the three regions for an example of an olivine moon are as follows: crust, below 440 K; intermediate layer, 890 K; and core, 1240 K. The whole-moon relative permeability has been calculated from the measurements to be 1.03 plus or minus 0.13.

Dyal, P.↗
NASA NTRS1972

Shock melting and vaporization of lunar rocks and minerals.

The entropy associated with the thermodynamic states produced by hypervelocity meteoroid impacts at various velocities are calculated for a series of lunar rocks and minerals and compared with the entropy values required for melting and vaporization. Taking into account shock-induced phase changes in the silicates, we calculate that iron meteorites impacting at speeds varying from 4 to 6 km/sec will produce shock melting in quartz, plagioclase, olivine, and pyroxene. Although calculated with less certainty, impact speeds required for incipient vaporization vary from 7 to 11 km/sec for the range of minerals going from quartz to periclase for aluminum (silicate-like) projectiles. The impact velocities, which are required to induce melting in a soil, are calculated to be in the range of 3 to 4 km/sec, provided thermal equilibrium is achieved in the shock state.

Ahrens, T. J.↗
NASA NTRS1972

Occurrence of diopside and Cr-Zr-armalcolite on the moon.

Petrographic and electron-microprobe examination of the sample of 1 to 2 mm fines, Apollo 14166,6, has revealed a fragment with the unique lunar mineralogy of plagioclase, olivine, diopside, a Ti-Fe-Zr phase, and a trace of ilminite. The second occurrence of diopside is reported together with the third occurrence of a recently identified Ti-Fe-Zr phase. Microprobe analyses of the principal phases of the fragment studied are presented in a table. The relatively pure diopside analyses reported represent the most Mg-rich calcic pyroxene found in lunar material.

Steele, I. M.↗
NASA NTRS1972

The Seoni chondrite.

Description of the Seoni (India, 1966) chondrite in terms of its mineralogy, bulk chemistry, and sample shape and mass. It is an H6 group ordinary chondrite that contains olivine, orthopyroxene, clinopyroxene, plagioclase, together with chromite, troilite, kamacite, taenite, chlorapatite, and whitlockite. Recrystallization has been quite extensive, as indicated by the presence of a few remnant chondrules, low abundance of clinopyroxene, and relatively high abundance of well formed plagioclase.

Bunch, T. E.↗
NASA NTRS1972

Elasticity of some mantle crystal structures. I - Pleonaste and hercynite spinel.

The elasticity of high-pressure mantle phases can be characterized by using data for chemically similar crystal compounds. The single-crystal elastic constants are determined as a function of pressure and temperature for pleonaste spinel and at room conditions for hercynite spinel. The bulk modulus increases from 1.95 Mb for pleonaste spinel to 2.10 Mb for hercynite spinel. Low or negative values of the pressure derivatives of shear constants are characteristic of the spinel structure and imply a low kinetic barrier to phase transformations and diffusion. Compressional and shear velocities of the spinel phase of olivine are estimated as a function of mean atomic weight by using the pleonaste and hercynite data.

Wang, H.↗
NASA NTRS1973

Photometric and polarimetric properties of the Bruderheim chondritic meteorite

Photometric and polarimetric laboratory measurements were made as a function of phase angle in the U(0.36 microns), G(0.54 microns) and R(0.67 microns) bands for 0, 30 and 60 deg incident illumination on four particle size ranges of Bruderheim, an L6 olivine-hypersthene chondritic meteorite. The four particle size ranges were: 0.25-4.76 mm coated with less than 74 microns powder, 74-250 microns, and less than 37 microns. In addition, normal reflectance measurements were made in the spectral range from 0.31 to 1.1 microns. Comparison with astronomical data reveals that none of the asteroids in the main belt for which adequate observations exist can be matched with Bruderheim, which is representative of the most common meteoritic material encountered by the Earth. However, it appears from the polarization and photometry data that the surface of the Apollo asteroid Icarus is consistent with an ordinary chondrite composition. This suggests the possibility that this material, although common in Earth-crossing orbits, is rare as a surface constituent in the main asteroid belt.

Egan, W. G.↗
NASA NTRS1972

Pyroxenes from breccia 14303.

Review of the investigation results obtained on the adjacent polished thin sections 47 and 53 of breccia 14303, the largest rock returned by Apollo 14 for which a location has not been established. A basaltic lithic clast, composed mainly of plagioclase, olivine, and pigeonite zoned to subcalcic augite, is found to occupy the same relative position in both sections and is assumed to represent a single lithic chip. Further study of lithic and fragmental clasts in breccias is seen likely to yield information on lunar history between 4.6 and 3.9 b.y. ago.

Weigand, P. W.↗
NASA NTRS1972

Experimental petrology and origin of Fra Mauro rocks and soil.

Results of melting experiments over the pressure range from 0 to 20 kb on Apollo 14 igneous rocks 14310 and 14072, and on comprehensive fines 14259. It is found that low-pressure crystallization of rocks 14310 and 14072 proceeds as predicted from the textural relationships displayed by thin sections of these rocks. The mineralogy and textures of these rocks are the result of near-surface crystallization. The chemical compositions of these lunar samples all show special relationships to multiply saturated liquids in the system anorthite-forsterite-fayalite-silica at low pressure. Partial melting of a lunar crust consisting largely of plagioclase, low-calcium pyroxene, and olivine, followed by crystal fractionation at the lunar surface, is a satisfactory mechanism for the production of the igneous rocks and soil glasses sampled by Apollo 14. The KREEP component of other lunar soils, may have a similar origin.

Walker, D.↗