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  • 1
    Publication Date: 2011-08-19
    Description: Ultrapure minerals separated from eclogite inclusions in kimberlites were analyzed for Sm, Nd, Sr, and oxygen isotopes and for major and trace elements. Clinopyroxene (cpx) and garnet (gnt) are the only primary mineral phases in these rocks, and mineral phases and their alteration products. The WR sub calc. is the reconstructed bulk composition excluding all the contamination influences. Two groups of eclogites: are distinguished: (1) type A Noritic-anorthositic eclogites; and (2) type B Ti-ferrogabbroic eclogites. The oxygen isotopes are primary mantle-derived features of these rocks and are not caused by posteruption processes, as they were measured on unaltered, clean mineral separates and show a correlation with REE pattern and Sr and Nd isotopes. It is suggested that the variation of the oxygen isotopes are caused by crustal-level fluid-rock interaction at relatively low temperature. It is shown that oxygen isotopes variation in MORB basalts caused by the hydrothermal system are in the same range as the observed oxygen isotope variation in eclogites. A model to explain the new set of data is proposed. It is thought that some of these eclogites might be emplaced into the upper lithosphere or lower crust at the time corresponding to their internal isochron age. The calculated WR composition was used to estimate model ages for these rocks.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 40-41
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  • 2
    Publication Date: 2019-01-25
    Description: Kaidun is an unusual chondritic meteorite. Its main mass is of CR-type (Kaidun I) and contains CI-like (Kaidun II), EL, and EH clasts. The classification of Kaidun II based on mineralogy and bulk chemical criteria does not allow an unambigious assignment to CI. Here we report on the bulk chemical composition and the mineralogy of the Kaidun II clasts. The results of our investigation show that Kaidun II has some characteristics of both CI and CM chondrites. A possible relationship to the texture and composition of micrometeorites is indicated. The Kaidun II clast shows some conflicting mineralogical and chemical characteristics that do not allow an unambigious assignment to the well established carbonaceous chondrite classes. The overall texture of the matrix-rich clast and morphology of opaques are typical for CI's. Bulk matrix and bulk sample compositions reveal similarities with CM's. In addition, the presence of low-Fe Mn-enriched olivines and the relatively high abundance of enstatite resembles some micrometeorites.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 177-178
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  • 3
    Publication Date: 2019-01-25
    Description: The effects of oxygen fugacity and temperature on the solubility of Au in silicate melts were determined. Pd-Au alloys were equilibrated with silicate of anorthite-diopside eutectic composition at different T-fO2 conditions. The behavior of Au was found to be similar to that of Pd reported recently. Au solubilities for alloys with 30 to 40 at. percent Au decrease at 1400 C from 12 ppm in air to 160 ppb at a log fO2 = -8.7. The slope of the log(Me-solubility) vs. log(fO2) curve is close to 1/4 for Au and the simultaneously determined Pd suggesting a formal valence of Au and Pd of 1+. Near the IW buffer Pd and Au solubilities become even less dependent on fO2 perhaps reflecting the presence of some metallic Au and Pd.
    Keywords: METALLIC MATERIALS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 147-148
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  • 4
    Publication Date: 2019-06-28
    Description: The results of a study of the small achondrite found in 1974 near Brachina, Australia are presented and discussed. Trace element data for Brachina were found to be quite different from that for Chassigny. The major differences are higher FeO/MnO, Ge/Al, and K/La ratios, W depletion, high siderophile content, near-horizontal REE pattern at about 1 x chondrite level, high refractory/nonrefractory metal ratios (e.g., Ir/Au), and chalcophile element depletion. Brachina's 4.5 billion year age and oxygen isotropic signature within the eucritic field further suggest that it is not related to Chassigny or SNC meteorites, though it may be related to primitive meteorites, such as silicate inclusions in IAB irons and winonaites.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 88; B237-B24
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  • 5
    Publication Date: 2019-06-28
    Description: Single samples from three successive homogeneous but contrasting layers (anorthosite, anorthositic norite, and norite) in the Stillwater Complex Norite 1 subzone were subjected to detailed petrographic and major and trace element chemical analyses. The petrography and the element chemistry of the three layers are found to be generally consistent with formation from a common magma, although a simple model of liquidus phases and trapped magma is not quite consistent with petrography and chemistry. Changes of oxidation level from layer to layer are indicated by both iron in plagioclase and by the distribution coefficient for Eu required for compatibility with a common parent. Such oxidation changes can explain qualitatively the Mg/Fe variation otherwise attributed to trapped liquid. The data demonstrate that for individual lunar highlands igneous rocks, a general picture of the parent magma can be derived, but detailed petrochemical comparisons using a simple trapped liquid model might deny a common parentage for two samples when such in fact existed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; C591-C60
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  • 6
    Publication Date: 2019-06-28
    Description: The compositional and petrologic characteristics of the Johnstown meteorite show it to contain uncontaminated and unbrecciated orthopyroxenite clasts of cumulative origin that (1) must have undergone subsolidus recrystalization, (2) are parental to the brecciated matrix, and (3) show no evidence of a xenolithic, meteoritic contribution to the matrix except for contamination by the projectile which crushed it on impact. The trapped liquid was not introduced in the impact process. The variability of such trace elements as the light rare earth elements, and the presence of plagioclase and olivine in only one of the thin sections studied, demonstrates the heterogeneity of coarse-grained diogenites on a millimeter scale and the difficulty of obtaining representative samples of such meteorites. The data presented indicate that this meteorite is a monominct breccia.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta; 45; Dec. 198
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  • 7
    Publication Date: 2019-07-13
    Description: Apollo 11 fines and rocks major and trace elements data obtained by combined instrumental and neutron activation analysis
    Keywords: SPACE SCIENCES
    Type: APOLLO 11 LUNAR SCIENCE CONFERENCE; Jan 05, 1970 - Jan 08, 1970; HOUSTON, TX
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