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Now showing items 10573-10592 of 39003
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(2001)Mineral, chemical, and isotopic (C, O) compositions were studied in carbonatite-like rocks from 11 areas in the Nizhnyaya and the Podkamennaya Tunguska drainage basins. Based on the internal structures and mineral compositions ...
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(2003)For five tektite glasses (moldavites, indochinites, and irgizite), oxygen fugacity (fO2) was measured within the temperature range of 800-1150°C using solid electrochemical cells, and water content was analyzed with FTIR ...
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OXYGEN AND HYDROGEN ISOTOPE COMPOSITIONS IN CLAY MINERALS: A POTENTIAL SINGLE-MINERAL GEOTHERMOMETER (1996)The opposite slopes of the isotopic fractionation of hydrogen and oxygen in the clay-water system and the well-known relationship between δD and δ18O in meteoric waters allow the isotopic composition of clay minerals to ...
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(2000)Hydration complexes of the ions Li+, Na+, Mg2+, F-, Cl-, and Br- that are expected to occur in natural brines, hydrothermal solutions, or volcanic vapors were studied theoretically using quantum mechanical methods, in ...
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(1999)The oxygen and hydrogen isotope compositions of minerals and whole rock were determined for two types of gneiss (biotite gneiss and granitic gneiss) associated with ultrahigh pressure (UHP) eclogites in the Shuanghe district ...
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(2001)Bacterial disproportionation of elemental sulfur is an important process in the sulfur cycle of natural sediments and leads to the formation of hydrogen sulfide and sulfate. The oxygen atoms in sulfate during this anaerobic ...
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(2003)Considered is the problem of diffusion viscosity η determination for minerals (or rocks) with ideal crystalline structure. The calculation is conducted according to the formula: η=(0.05T/D)exp(E/RT), where T - temperature, ...
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(1997)Oxygen diffusion in natural, non-metamict zircon was characterized under both dry and water-present conditions at temperatures ranging from 765°C to 1500°C. Dry experiments were performed at atmospheric pressure by ...
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(1999)The oxidation states of Ni, Co, Mn, Cr, V and Si in magnesiowüstite have been determined in metal-oxide distribution experiments using a multi anvil apparatus at 9 and 18 GPa and 2200°C as a function of oxygen fugacity. ...
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(1996)The oxygen isotopic composition of phosphate (δ18Op) and structural carbonate (δ18Oc) of hydroxylapatite was determined in 31 bone and tooth samples of modern mammals from different countries. These two variables are highly ...
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(1997)The δ18O values of fine-grained materials made with the laser-extraction technique are often lower than those obtained conventionally. We propose a simple method to overcome this problem that involves the mixing of samples ...
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(2002)A comparison has been made of oxygen isotope analyses of natural and synthetic phosphates using three methods in current use and Ag3PO4 as the analyte. Of these methods, conventional fluorination using BrF5 provides the ...
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(1994)Spinel and garnet fades peridotites from the Vitim Volcanic Field in Siberia comprise a suite of fertile mantle xenoliths, which are LREE depleted and have strongly depleted strontium and neodymium isotopic compositions. ...
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(1997)Data from the Nansen Basin of the Arctic Ocean are used to investigate the habitat and conditions under which the polar planktic foraminifer Neogloboquadrina pachyderma (sin.) calcifies. The vertical distribution of δ18O ...
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(1994)The oxygen isotopic composition of 76 samples of olivine in spinel-, garnet- and diamond-facies peridotites, and as syngenetic inclusions within diamond has been determined by laser fluorination (LF). δ18OV-SMOW values of ...
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(1998)The oxygen isotope ratio of diopside correlates with crystal size in many high grade marbles, permitting the intracrystalline self-diffusion rate of oxygen in diopside to be empirically evaluated.Small (75-300 μm) and large ...
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(2003)In the Sm-Nd and Rb-Sr isotopic geochronology of metamorphic rocks, an important question is whether radiometric systems of mineral isochrons have achieved isotopic equilibrium during a given metamorphic event and preserved ...
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(2005)We measured oxygen isotope compositions of 34 adakites, high-Mg andesites, and lavas suspected to contain abundant slab and sediment melts from the Western and Central Aleutians, the Andes, Panama, Fiji, Kamchatka, Setouchi ...
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(1999)Oxygen isotope compositions of individual mineral grains in two spinel-bearing chondrules have been determined by secondary ion mass spectrometry. O isotope ratios of spinel grains in a plagioclase-rich chondrule were ...
Now showing items 10573-10592 of 39003