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Philpotts, J. A.

Publications and source records attributed to Philpotts, J. A..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Geochemical data synthesis and analysis

Data obtained at the Goddard Flight Center were collected for the purpose of completing analyses started at Goddard in order to maximize the scientific yield of the geochemistry program which was terminated in 1977. The major analytical task undertaken was to complete Gd analyses on a large number of samples already analyzed by mass spectrometry for other rare earth element abundances at Goddard. Gd values are important for pinning down the central part of the geochemically significant rare earth abundance pattern and are especially useful in the high precision definition of the utilitarian Eu anomaly. Isotope-dilution Gd abundances were obtained for 39 samples. The data are for 27 partition-coefficient samples, six Apollo 15 and 16 breccia samples, four terrestrial impactities, and associated rock standards.

Philpotts, J. A.↗
NASA NTRS1978

The law of constant rejection

Improvements in analytical technique, study of multielement partitioning in natural systems, and improvements in ionic radius values have permitted construction of Onuma diagrams, in which the logarithm of partition coefficient is plotted versus ionic radius. The optimum radii, corresponding to crystallographic sites, do change in response to changes in major element composition for any particular mineral-type. In natural systems elements compete for sites rather than substituting for another element. It is proposed on empirical grounds, for equilibrium ionic bonding, that Onuma diagram curves for a particular lattice site are parabolic near optimum radius, linear elsewhere, parallel for different valences, and mirror images on opposite sides of optimum. Deviations may be due to overlapping peaks, liquid structure, polyvalence, bonding differences, contamination, kinetics, alteration, etc. However, dominant crystal-chemical control is indicated.

Philpotts, J. A.↗
NASA NTRS1978

Trace element partitioning between ionic crystal and liquid

The partitioning of trace elements between ionic crystals and the melt has been correlated with lattice energy of the host. The solid-liquid partition coefficient has been expressed in terms of the difference in relative ionic radius of the trace element and the homogeneous and heterogeneous strain of the host lattice. Predictions based on this model appear to be in general agreement with data for alkali nitrates and for rare-earth elements in natural garnet phenocrysts.

Tsang, T.↗
NASA NTRS1977

Trace element distribution in mineral separates of the Allende inclusions and their genetic implications

Concentrations of the rare earth elements (REE), Sc, Co, Fe, Zn, Ir, Na, and Cr were determined for mineral separates of the coarseand fine-grained types (group I and II) of the Allende inclusions. These data in combination with other data suggest that the minerals in the coarse-grained inclusions (group I) crystallized in a closed system with respect to refractory elements although a totally molten stage is precluded. The data also indicate that fine-grained (group II) inclusions were formed by condensation from a super-cooled nebular gas; REE-rich clinopyroxene and spinel were formed earlier than REE-poor sodalite and nepheline. In addition, pre-existing Mg isotope anomalies in the coarse-grained inclusions must have been erased during the heating stage.

Nagasawa, H.↗
NASA NTRS1977

Lunar surface chemistry - A new imaging technique

Detailed chemical maps of the lunar surface have been constructed by applying a new weighted-filter imaging technique to Apollo 15 and Apollo 16 X-ray fluorescence data. The data quality improvement is amply demonstrated by (1) modes in the frequency distribution, representing highland and mare soil suites, which are not evident before data filtering, and (2) numerous examples of chemical variations which are correlated with small-scale (about 15 kilometer) lunar topographic features.

Andre, C. G.↗
NASA NTRS1977

The Apollo 17 'melt sheet' - Chemistry, age and Rb/Sr systematics

Major, minor, and trace-element compositions, age data, and Rb/Sr systematics of Apollo 17 boulders have been compiled, and additional analyses performed on a norite breccia clast (77215) included in the Apollo 17, Station 7 boulder. The Apollo 17 boulders are found to be identical or nearly so in major, minor, and trace-element composition, suggesting that they all originated as an impact melt analogous to melt sheets found in larger terrestrial craters. The matrix dates (Ar-40/Ar-39) and Rb/Sr systematics available suggest that this impact melt formed by a single impact about 4 billion years ago. This impact excavated, shocked, brecciated, and melted norites, norite cumulates, and possibly anorthositic gabbros and dunites about 4.4 billion years old. The impact was likely a major one, possibly the Serenitatis basin-forming event.

Winzer, S. R.↗
NASA NTRS1977

Chemical character of the partially flooded Smythii Basin based on Al/Si orbital X-ray data

Orbital X-ray fluorescence data indicate that continuous mare-basalt flooding is confined to the northeastern quadrant of the Smythii Basin. Al/Si values for soils in the unflooded northwestern section of the Smythii Basin closely approximate those for the adjacent terra to the west. Terra soils east of Mare Smythii, however, are unusually aluminous compared to terra soils west of the basin. This pronounced contrast between Al/Si values for terra soils to the east and west of Smythii as well as the minimal difference in values between the northwestern section of the basin and adjacent terra to the west are most likely due to a chemically homogeneous layer of ejecta from a large impact event west of Mare Smythii, such as that which formed the Crisium Basin. An alternate hypothesis is that the unflooded section of the basin is predominantly original basin floor material, indicating that the impact forming the 4km deep Smythii Basin did not penetrate into a horizon chemically different from the terra west of Smythii. The chemical contrast between the terra east and west of Smythii, then, would be ascribed to lateral heterogeneity within the lunar crust

Andre, C. G.↗
NASA NTRS1977

The petrology and geochemistry of impact melts, granulites, and hornfelses from consortium breccia 61175

The matrix and 58 clasts from breccia 61175 were analyzed for major, minor, and trace elements. The matrix is anorthositic and has lithophile trace element abundances 20 to 40 times chondrite. Clasts comprise impact melt rocks, xenocryst and xenolith-free very high aluminum (VHA) and anorthositic basalts, anorthosite, anorthosite-norite-troctolite granulites, and hornfelses. The VHA and anorthositic basalts are considered to be impact melts, and the hornfelses were probably formed by incorporation of breccias or preexisting melt rocks into a melt sheet prior to cooling. The range of melt-rock lithophile trace element abundances might indicate more than one melt sheet.

Winzer, S. R.↗
NASA NTRS1977

Geochemical studies of the White Breccia Boulders at North Ray Crater, Descartes region of the lunar highlands

The samples of the White Breccia Boulders obtained during the Apollo 16 mission and investigated in the reported study include an anorthositic breccia (67415), a dark matrix breccia (67435), a light matrix breccia (67455), and a large clast of dark matrix breccia (67475) taken from the 67455 boulder. The chemical analyses of bulk samples of the samples are listed in a table. A graph shows the lithophile trace element abundances. Another graph indicates the variation of Sm with Al2O3 content for samples from the White Breccia Boulders. The North Ray Crater breccias are found to be in general slightly more aluminous than breccias from the other stations at the Apollo 16 site. Analyses of eight Apollo 16 breccias cited in the literature range from 25% to 35% Al2O3. However, the North Ray Crater breccias are more clearly distinct from the other Apollo 16 breccias in their contents of lithophile trace elements.

Lindstrom, M. M.↗
NASA NTRS1976

A correlation study based on Al/Si X-ray fluorescence data from southwestern part of Mare Serenitatis

A correlation study based on Al/Si intensity ratios, broad-spectrum visible-albedo measurements, color-difference photography, color-ratio images, and spectral-reflectivity curves was undertaken to understand why the Tacquet Formation in southwestern Mare Serenitatis has unusually low visible albedos for the Al/Si intensity ratios measured by the Apollo 15 X-ray fluorescence experiment. The statistical analysis of the Al/Si data is described, general correlations among all the remote-sensing data are noted, and correlations in the area of the Tacquet Formation are examined. It is shown that the discrepancy between visible albedos and Al/Si intensities may be due primarily to the presence of unevenly deposited highland-type ejecta from Menaleus crater, although the possibility cannot be excluded that the Tacquet Formation is more complex than a simple mixture of highland and mare materials.

Andre, C. G.↗
NASA NTRS1976

The remarkable chemical uniformity of Apollo 16 layered deep drill core section 60002

Atomic absorption and colorimetric spectrophotometers were used to determine major- and minor-element abundances in 12 samples from layered section 60002 of the Apollo 16 deep drill core. It is suggested that gardening of a relatively thick local unit produced the layering in this section in such a manner that the proportions of materials of different compositions remained virtually unchanged.

Nava, D. F.↗
NASA NTRS1976

A geochemical anomaly contiguous with the Dorsa Geike wrinkle ridge in Mare Fecunditatis

The orbital Al/Si X-ray fluorescence data from Apollo 15 and 16 reveal a concentration of unusually low Al/Si intensity ratios associated with a 220-km long ray along the northeast-southwest trending wrinkle ridge, Dorsa Geike, of the Mare Fecunditatis. The paper describes in detail the analysis of the Al/Si X-ray fluorescence data by which this geochemical anomaly was discovered. Correlation with other remote sensing data also indicates that the ridge area is different from the rest of the mare. It is possible that the material associated with the low Al/Si intensity ratio is of different composition than the adjacent mare regolith. Downslope transport along the ridge and arch could expose basalts which contrast chemically with surrounding regolith. The anomaly could also be due to extrusion of a volcanic rock of different composition at the fracture system represented by the wrinkle ridge.

Andre, C. G.↗
NASA NTRS1975

Origin of the Station 7 boulder - A note

The origin of the matrix types from the Apollo 17 Station 7 boulder is considered along with the origin of boulder material from Station 2, Boulder 1, and 73215. It is pointed out that the formation of the matrix rocks in this boulder and in the other Apollo 17 boulders in a single impact event is consistent with the isotopic evidence, ages, major-element chemistry, large ion lithophile (LIL) trace-element abundances, and textures. It had been suggested by Winzer et al. (1974), based on calculations from crystal-liquid partition coefficients for LIL trace elements, that target rocks corresponding in trace-element composition to the matrix types could have been produced by partial fusion of rocks similar to 77215. Using the same type of calculation, liquids quite similar in trace-element composition to the Station 7 boulder matrix types can be produced.

Winzer, S. R.↗
NASA NTRS1975

Origin of 78235, a lunar norite cumulate

A chemical and petrographic study is reported of the phases from the rock 78235 which was returned on the Apollo 17 mission. Petrographic analysis of the thin sections from the bounder confirm its cumulate origin. In order to develop further the crystallization history for 78235, its subsequent shock history, and its relationship to other lunar crustal rocks, orthopyroxene, plagioclase, glass, and whole-rock samples were prepared and analyzed for major, minor, and trace elements. It is speculated that an early fractional crystallization event producing a layer of orthopyroxene-plagioclase cumulate with varying amounts of trapped liquid took place within 20 km of the surface of the moon.

Winzer, S. R.↗
NASA NTRS1975

Correlation of Al/Si X-ray fluorescence data with other remote sensing data from the Taurus-Littrow area

Al/Si intensity ratios from the Apollo 15 X-ray fluorescence experiment have been analyzed in conjunction with such other remote-sensing data as visible albedo measurements, color-difference photographs, and relative spectral reflectivity curves for the purpose of defining geochemical units in the Taurus-Littrow area. A geochemical boundary between the dark-mantle unit and the western edge of the Taurus Mountains is indicated by all the remote-sensing techniques considered. The major component of the ejecta from Catena Littrow, located within the dark-mantle unit, is highland-type material. The areal extent of the ejecta determined from the Al/Si data is at least 30 km along the Apollo 15 ground track. The constraint imposed upon depth to high-alumina material at Catena Littrow is 520 m. If the high-alumina material excavated at Catena Littrow is an extension of the Taurus Mountain 'roots', then the maximum slope of the buried highland surface from Catena Littrow to the Taurus Mountains border is less than 2.0 deg

Andre, C. G.↗
NASA NTRS1974

Origin of Apollo 17 rocks and soils

Lithophile trace element abundances have been determined by mass spectrometric isotope dilution for a suite of Apollo 17 samples. The six mare basalts have generally similar relative trace element abundances; they are also similar to Apollo 11 trace element poor basalts. It is suggested that these basalts were derived by partial fusion of cumulates. The Apollo 17 highland breccias show an order of magnitude range in trace element abundances although there is a clustering of KREEP-rich samples which are interpreted as mixtures. The Apollo 17 soils show only a limited range of trace element abundances. They are mixtures of highland breccias, mare basalts, and orange-black 'soil'. There appear to be two groups of soils, Light Mantle and the rest. Both groups seem to have the same basalt component, which is similar to Station 4 basalt from Shorty Crater and probably is the uppermost basalt unit throughout the Taurus-Littrow valley.

Philpotts, J. A.↗
NASA NTRS1973

A lunar differentiation model in light of new chemical data on Luna 20 and Apollo 16 soils.

Fines from a Luna 20 soil sample and from three Apollo 16 deep drill core samples have been analyzed for major-minor element abundances by a combined, semi-micro atomic absorption spectrophotometric and colorimetric method. Both the major element and large ion lithophile trace element abundances in these soils, the first from interior highland sites, are greatly influenced by the very high normative plagioclase content, being distinctly richer in Al and Ca, and poorer in K, P, Cr, Mn, Fe, and Ti, than most bulk soil samples from previous lunar missions. The relatively large compositional variations in the Apollo 16 core can be ascribed almost entirely to decreasing plagioclase with increasing depth. The chemical composition of the Luna 20 soil indicates less plagioclase and less KREEP than in the Apollo 16 soils. A lunar differentiation model is presented in which is made the suggestion that KREEP is the result of a second fusion event in a lunar crust consisting of early feldspathic cumulates and primary aluminous 'liquid.'

Nava, D. F.↗