Engineering topics
Publications and source records attributed to Goles, G. G..
Variations in initial 187-Os/188-Os for SNC meteorites correlate with epsilon 142-Nd and epsilon 182-W, indicating that the Re-Os systematics were during the earliest differentiation history of Mars.
Forty-nine sub-samples of the polymict breccia 14321,184 have been excavated from the rock and analyzed by instrumental activation analysis techniques, specially modified to allow examination of small samples. Two distinct types of microbreccia clasts were analysed. A mare-type basalt of unusual composition is present as several discrete clasts. Mixing models for the clastic components of the breccia illustrate that at least three stages of assembly may be distinguished on compositional grounds. The first was at a site such that KREEP-rich materials dominated the clastic rocks formed, although a variety of lithic fragments were apparently present. The second assembly stage may have been primarily that of comminution and mixing of the more primitive materials, with addition of mare-type basalt clasts. The third stage saw addition of clasts of 14321-type basalt. In the final assembly stage, the light matrix was apparently formed entirely by mutual abrasion of the pre-existing clasts, resulting in little or no change in bulk composition.
Trace element compositions of petrographically characterized 2-4 mm lithic fragments from Apollo 16 soil samples are used to calculate initial REE concentrations in liquids in equilibrium with lunar anorthosites and to discuss the provenance of the Cayley Formation. Lithic fragments may be subdivided into four groups: (1) ANT rocks, (2) K- and SiO2-rich mesostasis-bearing rocks, (3) poikiloblastic rocks, and (4) (spinel) troctolites. Model liquids in equilibrium with essentially monominerallic anorthosites have initial REE concentrations 5-8 times those of chondrites. The REE contents of K- and SiO2-rich mesostasis-bearing rocks and poikiloblastic rocks are dominated by the mesostasis phases. ANT rocks appear to be more abundant in the Descartes Mountains, while poikiloblastic rocks appear to be more abundant in the Cayley Plains. Poikiloblastic rocks have intermediate to high LIL-element concentrations yet the low gamma-ray activity of Mare Orientale implies low LIL-element concentrations. Consequently, it is unlikely that the Cayley Formation is Orientale ejecta. A local origin as ejecta from smaller impacts is a more plausible model for the deposition of the Cayley Formation.
Trace and major element contents obtained by instrumental neutron activation are reported for a number of Apollo 16 soil samples and miscellaneous breccia fragments. In addition, data obtained by instrumental neutron activation and electron microprobe techniques along with petrographic descriptions are presented for selected subsamples of breccia 66055. The compositions of our soil samples can be modeled by mixtures of various amounts of anorthosite, anorthositic gabbro and low-K Fra Mauro basalt components. These mixtures are typical of those found in a number of petrographic surveys of the fines. Breccia 66055 is a complex regolith breccia which consists of at least four distinct types of microbreccias. No systematic relation with respect to stratigraphic age among the various microbreccia types was observed. Compositionally and texturally, the clasts which compose breccia 66055 are similar to a number of previously reported rock types from the Apollo 16 area. The entire breccia appears to have undergone a complex history of thermal metamorphism. We conclude from the study of these samples that the Cayley Formation is probably homogeneous in its gross compositional and petrographic aspects.
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Ninety sub-samples of Apollo 15 materials have been analyzed by instrumental neutron activation analysis techniques for as many as 21 elements. Soil and soil breccia compositions show considerable variation from station to station although at any given station the soils and soil breccias were compositionally very similar to one another. Mixing model calculations show that the station-to-station variations can be related to important local geologic features. These features include the Apennine Front, Hadley Rille and the ray from the craters Aristillus or Autolycus. Compositional similarities between soils and soil breccias at the Apollo 15 site indicate that the breccias and soils are related in some fundamental way, although the exact nature of this relationship is not yet fully understood.
Measurement of abundances of Na, Al, Sc, Cr, Mn, Fe, Co, and Cu by instrumental neutron activation analyses of 103 chondrites and 17 achondrites. Various sources of error in the method, including sampling errors, are discussed in detail. Examination of the patterns of coherence of the elements determined suggests the presence of effects of fractionation during condensation from the solar nebula of matter parental to chondrites. Such effects seem to be exhibited both in the abundances of lithophilic elements, perhaps being related to varied temperatures of accretion and in the abundances of those elements which would be affected by metal-silicate fractionation in the solar nebula. Atomic abundances relative to Si vary little in carbonaceous chondrites, suggesting that efficient mixing processes operated on these meteorites prior to or during their formation. It is suggested that, at present, no single class of carbonaceous chondrites is clearly more primitive than another. Carbonaceous and unequilibrated ordinary chondrites may represent aggregates of material accreted from the solar nebula at relatively low temperatures. The present data support a model of equilibration and minor mobilization of nonvolatile elements within small domains of chondrites after accretion. Such a model would be consistent with the petrologic types of Van Schmus and Wood (1967).
Consideration of the relationships of craters to scarps and ridges and of the antiquity of Hellas relative to the cratered terrain. Scarps and ridges in the transition zone between Hellas and the cratered terrain both postdate and predate large craters. It appears that there are a number of craters which are older than the transition zone structures, which in turn are presumably related in some way to the formation of Hellas. Sharp et al. (1971) have suggested impact, large-scale volcanic explosion, or subsidence for the origin of Hellas. Volcanic explosion seems the least likely explanation, for the resulting deficiency of mass beneath Hellas should induce later isostatic rebound, contrary to observations of the transition zone which imply subsidence relatively late in the history of the Martian surface. An origin of Hellas by impact with later isostatic subsidence (because of a dense mass under its floor, as suggested by Sharp et al.) to account for the characteristics of the transition zone seems to be the best model, and may also account for the featureless floor of the basin.
Eighty-two subsamples of Apollo 14 materials have been analyzed by instrumental neutron activation analysis techniques for as many as 25 elements. In many cases, it was necessary to develop new procedures to allow analyses of small specimens. Compositional relationships among Apollo 14 materials indicate that there are small but systematic differences between regolith from the valley terrain and that from Cone Crater ejecta. Fragments from 1-2 mm size fractions of regolith samples may be divided into compositional classes, and the 'soil breccias' among them are very similar to valley soils. Multicomponent linear mixing models have been used as interpretive tools in dealing with data on regolith fractions and subsamples from breccia 14321. These mixing models show systematic compositional variations with inferred age for Apollo 14 clastic materials.
Instrumental activation analyses of abundances in lunar rock chips
Apollo 12 specimens elemental abundance from neutron activation analysis, discussing fractional crystallization, partial melting, rare earth abundances and soil mixing model
In light of the new data of Jerome (1970), a brief discussion of genetic relationships between eucrites, howardites and diogenites is presented. Howardites are not direct products of magmatic crystallization, as has sometimes been postulated, but instead are interpreted as polymict breccias resulting from the mechanical mixture of eucrites and diogenites. Testing of this model by means of chemical arguments is made complicated however by the probable presence of a chondritic component in howardites and by a sequence analogous to terrestrial differentiation series, among the eucrites themselves.
Goethite stability on Mars, considering dehydration-rehydration cycle and time average atmospheric water vapor content
Apollo 11 lunar rocks elemental abundances determination by instrumental activation techniques
Apollo 11 sample elemental abundances, investigating environmental, paragenetic and petrogenetic problems and moon evolution
Element abundances in igneous rocks measured by instrumental neutron activation using high resolution lithium drifted germanium detectors
Cl, Br and I abundances in carbonaceous chondrites analyzed by neutron activation in estimating primordial halogen abundance ratios
Ultramafic rock content of Na, Mn, Cr, Sc and Co determined by neutron activation technique