Showing papers in "Chemical Geology in 1992"

TL;DR: In this article, 21 samples collected from a core of the 52.8 cm-thick Stark Shale Member of the Dennis Limestone in Wabaunsee County, Kansas, demonstrate four cycles with two-orders-of-magnitude variations in contents of Cd, Mo, P, V and Zn, and order-of magnitude variations in the contents of organic carbon, Cr, Ni, Se and U.

TL;DR: In this article, the rare-earth elements (REE) in seawater-pure synthetic mineral phase systems were investigated through standard batch equilibration experiments and the results from their adsorption studies were in agreement with features of REE patterns in natural deposits including the Ce anomaly found in deep-sea marine ferromanganese minerals and a general trend of preferential uptake of light relative to heavy (HREE) rare earth elements.

TL;DR: The Siwalik Sequence of northern Pakistan contains a 16-Ma record of carbonate and fossil teeth from which a record of paleovegetation can potentially be reconstructed and compared.

TL;DR: In this article, the Eu anomalies in banded iron formations (BIF's) were investigated using ICP-MS (inductively coupled-plasma mass spectrometry) and INAA (instrumental neutron activation analysis).

TL;DR: In this article, the dissolution rates of various natural calcite samples, e.g. marbles, limestones and marine pelagic sediments, were measured in CO2-H2O solutions of fixed PCO2 and temperature during their approach to equilibrium with respect to calcite.

TL;DR: In this article, the dissolution rate of fayalite as a function of pH at 25°C and 65°C was investigated with forsteritic olivine at pH 1.8, 6.0 and 9.8.

TL;DR: In this article, geochemical data for post-spreading seamount and island lavas define suites of quartz tholeiite, olivine tholeisite, alkali olivines basalt and nephelinite, characterised by OIB-type incompatible-element distributions.

TL;DR: In this article, carbon-sulfur relationships (evaluated on a calcium carbonate-free basis to avoid spurious correlations resulting from dilution effects) demonstrate that organic carbon and pyrite-S are essentially decoupled.

TL;DR: In this article, the authors measured field redox data from borehole investigations and calculated the solubility product for Fe(OH)3 with respect to the half-cell reaction with a precision of ± 25 mV.

TL;DR: In this paper, high-quality Raman spectra of silicate glasses, supercooled liquids and liquids have been obtained in situ to temperatures of 1475°C by focussing the diameter of the exciting laser beam to ∼ 1 mm, and to control the depth of focus in the sample to 6-40-μm depth.

TL;DR: The application of vibrational spectroscopy to the study of silicate liquids and glasses is described, and new Raman data for K 2Si2O5 and K2Si4O9 compositions are presented in this paper.

TL;DR: In this article, the authors compared results obtained from two commonly used sample preparation methods: LiBO2 fusion and open-vessel HF-HClO4 digestion, and compared them with data obtained from microwave-heated, sealedvessel, acid digestion.

TL;DR: In this paper, a combination of techniques is applied to zircon, allanite, sphene, apatite and thorite from both a tonalite and a granodiorite from the Tertiary Alpine Bergell intrusion.

TL;DR: In this paper, the structural properties of a series of SiO2-Al2O3 glasses with up to 59 mole% Al 2O3 were investigated by magic angle spinning NMR and infrared absorption spectroscopies.

TL;DR: In this article, it is proposed that EM2 derives from sub-continental lithosphere or asthenosphere reservoirs, enriched by subduction prior to crustal extension, and that Hainan basalts resemble Dupal-type oceanic island basalt and reflect mixing of EM2 and N-MORB mantle reservoirs.

TL;DR: In this article, the authors measured the oxygen and sulphur isotope compositions of the main evaporitic formations of Mesozoic and Cenozoic ages from Spain, for primary purposes, had to differentiate between marine and continental sulphate evaporites and also make it possible to determine the source of sulphate of the continental evaporites.

TL;DR: The ICP-AES and ICPMS are characterised by wide linear responses of more than five orders of magnitude as discussed by the authors, which can theoretically determine over 70 elements in the sample.

TL;DR: In this article, four distinct granitic magma series developed systematically in space and time during the evolution of the Southern Volcanic Zone of the Archean Abitibi granite-greenstone belt, Canada (∼ 2.75-2.67 Ga).

TL;DR: In this paper, a new technique for boron chemical separation and isotopic analysis in natural silicate rocks and waters is described, where sample dissolution and the subsequent ion-exchange chromatography were conducted using hydrofluoric and hydrochloric acids in the presence of mannitol which suppresses borone volatilization and isotope fractionation by the formation of a boroni-mannitol complex.

TL;DR: The compositional dependence of H2O solubility was investigated at 2 kbar and 800°C in haplogranite melts (system SiO21bNaAlSi3O81bKAlSi 3O8 or Qz1bAb1bOr) as discussed by the authors.

TL;DR: In this article, the presence of mantle-derived 3He in deep groundwaters is discussed in relation to the distribution of surface volcanics, tectonic activity, regional seismicity and heat flow.

TL;DR: The 13C and 18O contents of cryogenic calcites formed by expulsion during the freezing of bicarbonate groundwaters are examined in this article, showing that the rapid rate of reaction is shown to effectively preclude isotopic equilibration, resulting in a kinetic partitioning of 13C between CO2 and CaCO3.

TL;DR: In this article, the authors discuss the application of NMR spectroscopy to both kinds of approaches and present results, primarily from their laboratory, on anionic species distributions, on silicon and oxygen site exchange in liquids and its relationship to viscosity, and on quantification of the abundances of five-coordinated Si in high-pressure and 1-bar-pressure glass samples.

TL;DR: In this paper, a hypersaline system where acid groundwater enriched in K, Al, Fe(III) and SO 4 enter a salt playa lake was investigated. And the results showed that alunite and jarosite occur together or as individual layers and cements within the top 20 cm of the sediments, where the groundwater is most concentrated due to evaporation.

TL;DR: The rare earth element (REE) composition of ferromanganese deposits from the Hawaiian Archipelago was determined as part of a geochemical investigation into the origin and environment of deposition of crusts as mentioned in this paper.

TL;DR: In this article, chemical, crystallographic and isotopic analyses were made on samples containing alunite and jarosite from the sediments of four acid, hypersaline lakes in southeastern and southwestern Australia.

TL;DR: In this article, a small spring-fed stream precipitates calcite by outgassing of CO 2 due to chemically controlled inorganic processes and water analyses were carried out at the same time.

TL;DR: Several compositionally varied suites of plutonic rocks (gabbro-quartz monzogabbro, granite, quartz monzodiorite) in the Bunger Hills were emplaced at depths of ∼ 20 km over a relatively short time interval (1170-1150 Ma) during the waning stages of granulite-facies metamorphism, the peak of which occurred ∼ 1190 Ma ago as mentioned in this paper.

TL;DR: In this paper, the authors presented 29Si, 27Al and 23Na NMR data for a variety of dry and dydrous aluminosilicate glasses and showed that the data are consistent with a model for the mechanism of water dissolution which involves no breakage of T-O-T linkages.