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Showing papers in "Geochimica et Cosmochimica Acta in 1989"


Journal ArticleDOI
TL;DR: In this article, new abundance tables have been compiled for C1 chondrites and the solar photosphere and corona, based on a critical review of the literature to mid-1988.

10,322 citations



Journal ArticleDOI
TL;DR: It appears that distinct microenvironments may exist in marine sediments, where, in one microenvironment, sulfide reacts with Fe oxides locally precipitating Fe sulfide minerals, and in another, Fe reduced and solubilized by microorganisms migrates freely into solution.

983 citations


Journal ArticleDOI
TL;DR: In biological carbonates, two patterns of isotopic disequilibria are particularly common as discussed by the authors, i.e., kinetic and metabolic, which involve simultaneous depletions of 18O and 13C as large as 4%.

978 citations


Journal ArticleDOI
TL;DR: In this paper, a case is made that glacial-to-interglacial transitions involve major reorganizations of the ocean-atmosphere system, and that these reorganizations constitute jumps between stable modes of operation which cause changes in the greenhouse gas content and albedo of the atmosphere.

892 citations


Journal ArticleDOI
TL;DR: Isotope analyses of Os, Sr, Nd, and Pb elements were caried out on twelve peridotite xenoliths from the Jagersfontein, Letseng-la-terae, Thaba Patsoa, Mothae, and Premier kimberlites of southern Africa, to investigate the timing and the nature of melt extraction from the continental lithosphere and its relation to the continent formation and stabilization.

688 citations


Journal ArticleDOI
TL;DR: In this article, a model for the decomposition of organic matter in marine sediments is presented, which is based on organic carbon versus depth profiles of well-dated cores and laboratory experiments.

598 citations


Journal ArticleDOI
TL;DR: In this article, a chemical kinetic model is presented that uses Arrhenius rate constants to calculate vitrinite elemental composition as a function of time and temperature, which is valid for %Ro values from slightly less than 0.3 to slightly greater than 4.4.

596 citations


Journal ArticleDOI
TL;DR: A detailed and systematic study of the major ion chemistry of these rivers and their tributaries, as well as the clay mineral composition of the bed sediments has been conducted in this paper.

591 citations


Journal ArticleDOI
TL;DR: In this paper, rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge.

586 citations


Journal ArticleDOI
TL;DR: In this article, a new and simple mechanism of kerogen formation is proposed, which clarifies the interrelationships between extant biomass, kerogen, and fossil fuels, and it is shown that recognizable entities in kerogen and their extant counterparts suggest a new mechanism of formation.

Journal ArticleDOI
TL;DR: In vitro simulation of the calcifying environment produced heavy isotope depletions qualitatively similar to, but somewhat more extreme than, those seen in biological carbonates.

Journal ArticleDOI
TL;DR: In this paper, the authors compare the hard-sphere modified Redlich-Kwong equation of state of Kerrick and Jacobs (1981) and an empirical equation derived from the regression of available P-V-T data for the H2O-NaCl system.

Journal ArticleDOI
TL;DR: In this article, the pH-dependence of far from equilibrium steady-state dissolution rates of silicates can be understood by considering the detachment rates of their oxide components through surface protonation-deprotonation reactions.

Journal ArticleDOI
TL;DR: Wehrli and Stumm as mentioned in this paper showed that the rate of oxidation of VO2+ by oxygen is significantly enhanced by hydrolysis or adsorption to hydrous oxide surfaces and showed that coordinated OH-groups of solid surfaces are able to mediate the electron transfer from the metal ions to the O2-molecule.

Journal ArticleDOI
TL;DR: In contrast to its unreactive behavior in the open ocean, uranium is removed from seawater to sediments of anoxic marine basins such as the Black Sea by four biogeochemical processes: active uptake by organisms whose remains are preserved by the anoxic conditions of the sediments, complexation by particulate organic matter, chemical reduction of soluble U(VI) to insoluble U(IV) which is scavenged to the sediment by settling particles, and precipitation of uranium within the sediment themselves.

Journal ArticleDOI
TL;DR: In this paper, replicate neutron activation analysis was performed on 66 ordinary chondrites (22 H, 20 L, 17 LL, 2 intermediate between H and L and 5 intermediate between L and LL).

Journal ArticleDOI
TL;DR: In this article, a chemical equilibrium model is described which is used to calculate solubilities within experimental uncertainties in the Na-K-Ca-Cl-SO4-H2O system from zero to high ionic strength.

Journal ArticleDOI
TL;DR: Tetrahymanol has been identified in several sediment samples from different depositional environments by gas chromatography-mass spectrometry and by coinjections with an authentic standard as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, the bitumen of the Jurf ed Darawish Oil Shale has been analyzed for organic sulphur compounds (OSC) and a number of these compounds were reported for the first time: several C 28 8, C 37 and C 38 2,5-dialkylthiolanes and -thiophenes and 2,6-di-n -alkylthianes, and C 19 branched thiophens possessing the 9-methyl octadecane carbon skeleton.

Journal ArticleDOI
TL;DR: In this paper, a set of fractionation factors suitable for isotopic thermometry and for test of disequilibrium in natural systems is presented. But the results are compared with published theoretical estimates as well as data derived from hydrothermal experiments.

Journal ArticleDOI
TL;DR: In this article, the authors measured the oxidation of Fe(II) with H2O2 in seawater as a function of pH (2 to 8.5), temperature (5 to 45°C) and salinity (0 to 35).

Journal ArticleDOI
TL;DR: In this paper, two pyrolysis-gas chromatography (Py-GC) techniques were used to gain a succinct perspective of kerogen composition and structure which, by comparison with (13C NMR data, appears to be representative of the kerogen structure in toto.

Journal ArticleDOI
TL;DR: The ferric iron contents of spinels from 30 spinel Iherzolite xenoliths have been measured by 57 Fe Mossbauer spectroscopy as discussed by the authors, with an uncertainty of 0.2 to 0.3 mol%.

Journal ArticleDOI
TL;DR: The 3.0 Ga Pongola Supergroup of South Africa is one of the oldest well-preserved supracrustal successions as discussed by the authors, which is divided into the Nsuze and Mozaan groups.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed groundwaters from near surface to a depth of 1232 m in the Stripa granite and found that the groundwater composition consists of two general types: a typical recharge water of Ca-HCO3 type ( 700 m depth) of high pH (8-10) that reaches a maximum of 1250 mg/L in total dissolved solids (TDS).

Journal ArticleDOI
TL;DR: Based on geochemical studies of six spinel peridotite xenoliths in basanite, the upper mantle beneath Hannuoba, eastern China is compositionally heterogeneous as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, the solubility of gold was measured in aqueous sulfide solutions at pH from 3 to 8, 150° to 350°C, and at pressures determined by the liquid-vapor pressure of the solution, with oxidation state fixed or buffered by either sulfate-sulfide equilbria or H2(g).

Journal ArticleDOI
TL;DR: In this paper, the distributions of sulphur-containing compounds generated by flash pyrolysis of macromolecular sedimentary organic matter (kerogen, coal, asphaltenes) were studied by gas chromatography in combination with Sselective flame photometric detection or mass spectrometry.

Journal ArticleDOI
TL;DR: It is shown that the porphyrin isotopic record reflects primary isotopic variations more closely than the TOC isotopicrecord, and that, in these sediments, TOC is enriched in 13C relative to its primary precursor by 0.6 to 2.8%.