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Browsing ELibrary by Title
Now showing items 8670-8689 of 21934
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(1998)The occurrence of coexisting amphiboles in rocks and the likelihood of concurrent isotope closure allows equilibrium oxygen isotope fractionations among the amphiboles to be recovered from natural samples. Oxygen isotope ...
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(2004)We report a study of the oxygen isotope ratios of chondrules and their constituent mineral grains from the Mokoia, oxidized CV3 chondrite. Bulk oxygen isotope ratios of 23 individual chondrules were determined by laser ...
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(1995)Based upon a compilation and analysis of O-isotope data for Neogene volcanic rocks worldwide, the d18O variation for 743 basalts (historic lavas, submarine glasses, and lavas with 2O) is +2.9 to +11.4‰. Mid-ocean-ridge ...
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(1998)58 samples of fossil mammoth and reindeer teeth and bones of various ages and coming from different locations were studied for the oxygen isotopic composition of their phosphate. Samples from Siberia have interstadial ...
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(2003)The influence of NaCl, CaCl2, and dissolved minerals on the oxygen isotope fractionation in mineral-water systems at high pressure and high temperature was studied experimentally. The salt effects of NaCl (up to 37 molal) ...
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(2006)Phosphomonoesters are an important source of dissolved inorganic orthophosphate (PO4 or Pi), the preferred form of P utilized by microbiota and aquatic plants in marine and freshwater ecosystems. Two enzymes involved in ...
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(1999)The carbonaceous chondrites display the widest range of oxygen isotopic composition of any meteorite group, as a consequence of the interaction of primordial isotopic reservoirs in the solar nebula. These isotopic variations ...
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(1997)New data are reported for the 18O composition of hot hydrothermal fluids from various sites with different tectonic settings. The measured δ18O, in the range 0.53-2.3%% confirm earlier data suggesting that mid-ocean ridge ...
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(1997)Microbial activity has been invoked to explain anomalous oxygen isotope compositions of phosphate mineral deposits as well as fossil biogenic apatite. Results of laboratory experiments on enzyme-mediated reactions of ...
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(1997)Oxygen isotope ratios are reported for olivine phenocrysts from sixty-seven samples of ocean island basalts (OlBs), mid-ocean ridge basalts (MORBs), and related peridotites, including representatives of the various isotopic ...
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(2001)This chapter summarizes the oxygen isotope geochemistry of terrestrial basalts and their mantle sources, including the conceptual framework for interpreting such data and the phenomenology of known variations. In particular, ...
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(1989)The authors describe the fractionation of oxygen isotopes during the generation of horizontal and vertical metasomatic zoning in the typical greisen-rare metal Akchatau deposit in Central Kazakhstan. The oxygen isotope ...
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(2000)Calcium-aluminum-rich inclusions (CAIs) from enstatite chondrites have large 16O excesses, similar to CAIs in carbonaceous and ordinary chondrites, and are also similar in morphology, mineralogy and Al-Mg isotopic systematics. ...
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(2000)Ion-microprobe studies yield Δ17O (=δ17O - 0.52 . δ18O) values in magnetite from the Rumurti chondrite (RC) PCA91241 (which is paired with PCA91002) of +3.1 to +3.9%%, slightly higher than that in O from whole-rock R ...
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(2003)Isotopic and trace element analysis of zircons can provide reliable and robust estimates of age, compositions of coexisting minerals and melts, and constraints on the genesis and protoliths of host rocks. Recent technological ...
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(2001)In order to develop the potential tool of diatom oxygen isotopes for paleoenvironmental studies we compared oxygen isotopes of natural marine diatoms sampled from ocean surface water, sediment traps and surface sediments ...
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(1995)A simple and precise method of determining the oxygen isotopic composition of Ag3PO4 has been developed in which orthophosphate is condensed to pyrophosphate and higher polymeric forms at elevated temperatures using Br2 ...
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(2000)We have located small areas of siderite within the mesostasis of the Nakhla meteorite. High concentrations of Mn (up to ∼50% rhodochrosite) and elevated D/H ratios indicate that the siderite is not a terrestrial alteration ...
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OXYGEN ISOTOPIC COMPOSITION OF OPALINE PHYTOLITHS: POTENTIAL FOR TERRESTRIAL CLIMATIC RECONSTRUCTION (1996)Opaline mineralized bodies are produced by many terrestrial plants and accumulate in certain soils and archaeological sites. Analyses of the oxygen isotopic compositions of these so-called phytoliths from stems and leaves ...
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(2004)Oxygen isotopic compositions of silicate inclusions in IVA iron meteorites have been measured with an in situ UV laser microprobe technique. The homogeneity of oxygen isotopic compositions within and among individual mineral ...
Now showing items 8670-8689 of 21934