James L. Carter

Mineralogy and Chemistry of the Earth's Upper Mantle Based on the Partial Fusion-Partial Crystallization Model

Consideration of phase diagrams, mineralogical and chemical data, and textural evidence suggests that ultramafic and mafic nodules found in basaltic rocks at Kilbourne Hole, New Mexico, were formed by the interaction of partial fusion-partial crystallization processes. The olivine compositions of the nodules vary from 7 to 32 mol percent fayalite. Very few nodules were found with olivine compositions in the Fa 12 percent to Fa 14 percent interval, and significant mineralogical and chemical differences are found on either side of this compositional range. The model proposes that the original undepleted upper mantle composition falls in this range, and that it may be calculated from the modal and chemical data. Comparison of the chemical composition of the Earth9s mantle by models based on extraterrestrial data to the Earth9s unaltered upper mantle by Ringwood9s pyrolite model and Nicholl9s model, and to the partial fusion-partial crystallization model reveals convergence toward a similar over-all composition for the Earth9s undepleted upper mantle. The averaged undepleted upper mantle mineralogical composition for the major phases in volume percent under Kilbourne Hole, New Mexico, is: olivine, 50.9 ± 10.9; orthopyroxene, 21.7 ± 6.2; clinopyroxene, 23.0 ± 6.7; and spinel, 4.3 ± 1.2. The averaged undepleted, vapor-free, upper mantle chemical composition in weight percent under Kilbourne Hole, New Mexico, is: SiO 2 , 42.86 ± 0.32; TiO 2 , 0.33 ± 0.07; A1 2 O 3 , 6.99 ± 0.28; Cr 2 O 3 , 0.18 ± 0.04; total iron as Fe, 7.22 ± 0.17; MnO, 0.14 ± 0.01; NiO, 0.20 ± 0.01; MgO, 35.07 ± 0.24; CaO, 4.37 ± 0.11; Na 2 O, 0.45 ± 0.08; K 2 O, 0.003 ± 0.002; CoO, 0.014 ± 0.001; CuO, 0.0012 ± 0.0005; and ZnO, 0.0087 ± 0.0008.

Mineralogy, Petrology, and Surface Features of Lunar Samples 10062,35, 10067,9, 10069,30, and 10085,16

The primary rocks are a sequence of titanium-rich basic volcanics, composed of clinopyroxene, plagioclase, and ilmenite with minor olivine, troilite, and native iron. The soil and microbreccias are respectively loose and compacted mixtures of fragments and aggregates of similar rocks, minerals, and glassy fragments and spheres. Impact events are reflected by the presence of shock metamorphosed rock fragments, breccias, and glasses and their resulting compaction to form complex breccias, glass-spattered surfaces, and numerous glass-lined craters. Chemistry of the glasses formed by the impact events is highly variable, and the high iron and nickel content of a few moundlike features suggests that at least some of the projectiles are iron and nickel-rich meteorites.

Chemistry and surface morphology of soil particles from Luna 20 LRL sample 22003.

Abstract Six siliceous glass spheres, five siliceous glass-bonded agglutinates and one breccia fragment from Luna 20 LRL sample number 22003 were analyzed by optical microscope, scanning electron microscope, scanning electron microprobe and energy-dispersive techniques. The data suggest that most of the glass spheres were probably derived locally by meteoritic impact processes and that most craters on their surfaces may have occurred from impacts of relatively high velocity particles in the impact-produced debris cloud while the glass sphere was at elevated temperatures. This is suggested by the nature of the craters, the partially buried fragments of plagioclase surrounded by radiating fractures and by the apparent absence of craters on the glass surfaces of the glass-bonded agglutinates. One glass sphere has a surface suggestive of a complex multiple impact origin involving liquid siliceous material and numerous siliceous spherules from 0.1 μm to 1 μm in diameter that may have formed from vaporization and condensation processes possibly in a relatively large scale meteoritic impact event. The surfaces of the siliceous glass spheres have several different types of materials. Concentration of metallic iron spherules on the surfaces of the glass spheres is generally lower than for similar Apollo 11 and 12 glass spheres. This is consistent with reduction processes being of primary importance in the formation of this metallic iron. Surface material composed only of Ca, C and O 2 , possibly CaCO 3 , is probably derived from carbonaceous chondrites. Splashes of material rich in Ca, Al, Fe, K and Cl occur. The origin of the relatively low temperature chlorine-bearing melt is unknown but it may be related to vaporization and condensation processes, possibly volcanic in nature, or possibly to partial fusion of components of carbonaceous chondrites. Siliceous surface material rich in potassium may represent either fused splash material of granitic composition or material enriched by vaporization and condensation processes.

VLS (Vapor-Liquid-Solid): Newly Discovered Growth Mechanism on the Lunar Surface?

A probable vapor-liquid-solid (VLS) type of growth has been discovered for the first time in nature on the surface of lunar rock 15015. Scanning electron microprobe and energy dispersive x-ray data indicate that the growth occurs as metallic iron stalks from about 0.015 to 0.15 micrometer in diameter, with bulbous tips consisting of a mixture of iron and sulfur and measuring from about 0.03 to 0.2 micrometer in diameter. The stalk length is two to ten times the bulb diameter.