Showing papers in "Geochimica et Cosmochimica Acta in 2005"

TL;DR: In particular, the oldest piece of Earth as discussed by the authors contains both type-1 and type-2 patterns on a 50 μm scale, a phenomenon not yet reported for unaltered magmatic zircon.

TL;DR: In this article, the authors reported SIMS and EMPA analyses showing that As and Au contents of arsenian pyrites plot in a wedge-shaped zone with an upper compositional limit defined by the line of the line connecting the boundary of the wedge and the boundary between the zone of interest.

TL;DR: In this article, the authors extended the analysis of the mutual solubilities of CO2 and H2O to include the effect of chloride salts in the aqueous phase.

TL;DR: In this paper, the isotopic exchange between aqueous Fe(II) and iron oxides was investigated using isotope exchange experiments with 55Fe-labeled IR oxides.

TL;DR: In this paper, the chemical structure of refractory marine dissolved organic matter (DOM) is still largely unknown, and the authors compared two different types of DOM: algal-derived DOM from the Weddell Sea (Antarctica) and terrigenous DOM from pore water of a tropical mangrove area in northern Brazil.

TL;DR: In this paper, the experimental rate data for O2 oxidation of dissolved Mn(II) species at 25°C and to interpret the rates in terms of the solution species of Mn (II) in natural waters were assessed.

TL;DR: In this article, a monitoring program at the Obir Caves, an Austrian dripstone cave system characterized by a seasonally changing air flow that results in a predictable pattern of high pCO2 during summer and low p CO2 in winter.

TL;DR: In this article, a revision of Rees' model for bacterial sulfate reduction is presented, which includes revised fractionation factors for the sulfite-sulfide step and incorporates new forward and reverse steps in the reduction of sulfite to sulfide, as well as exchange of sulfide between the cell and ambient water.

TL;DR: In this article, a model for age correction for U-Th zoned crystals with bipyramidal terminations is presented. But the model is limited to spherical and prismatic grains.

TL;DR: In this article, major element, trace element and Nd-isotope data for 30 alluvial sediments collected from 25 rivers in Queensland, E Australia were presented.

TL;DR: In this paper, a large number of trace elements (Zr, Hf, Nb, Ta, V, Co, Cu, Zn, Sr, REE, Cr, Sb, W, U, Th) were determined for rutile.

TL;DR: In this article, the Fe3+/ΣFe ratio of 104 MORB glasses from the Pacific, the Atlantic, the Indian, and the Red Sea spreading centers has been determined using wet chemical Fe2+ analyses and electron microprobe FeOtotal measurements.

TL;DR: In this paper, the authors used the 182Hf-182W isotopic systematics of Ca-Al-rich inclusions, metal-rich chondrites, and iron meteorites to constrain the relative timing of accretion of their parent asteroids.

TL;DR: In this article, the authors describe pore water and sediment measurements of iron (Fe), manganese (Mn), vanadium (V), uranium (U), rhenium (Re), and molybdenum (Mo) along a transect off Washington State (USA).

TL;DR: The average rate of authigenic U uptake for all the sites examined here is ∼−0.2 nmol cm-2 y-1, which is consistent with published global estimates of sedimentary U uptake.

TL;DR: In this article, a theoretical framework was proposed to analyze a total of 55 sets of proton surface charge data referring to wide ranges of ionic strengths, and types of electrolyte and oxide.

TL;DR: In this paper, the isotopic composition of dissolved Si in weathering systems is determined by the combined effects of rock disintegration, clay mineral neosynthesis, and Si biocycling.

TL;DR: In this paper, the authors explored a novel mechanism during N mineralization by 15 N amendments (single and coupled additions of (NH4+)-N-15, (NO3-N-14, and (NO 3-)-n-15) to surface sediments with a wide range of characteristics and overall reactivity.

TL;DR: In this paper, a 2-site protolysis nonelectrostatic surface complexation and cation exchange (2SPNE SC/CE) model has been used to model the free energies of aqueous or surface metal complexes and thermodynamic properties of the metal ions or ligands.

TL;DR: In this paper, solid-state 1H and 13C NMR spectroscopic experiments have been performed on isolated meteoritic Insoluble Organic Matter (IOM) spanning four different carbonaceous chondrite meteorite groups; a CR2 (EET92042), a CI1 (Orgueil), a CM2 (Murchison), and the unique C2 meteorite, Tagish Lake.

TL;DR: In this article, the authors report elemental and Nd-Sr isotopic data for two coeval postcollisional magmatic suites (∼300 Ma), the Miaogou and Karamay suites, from West Junggar foldbelt (NW China), aiming to determine their source regions and implications for continental growth.

TL;DR: In this paper, the authors measured the peak shift of the sulfur Kα radiation relative to a sulfide standard, whereas oxygen fugacity was calculated from the composition of olivine and spinel present in the assemblages.

TL;DR: In this paper, Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the adsorption of uranyl (UO22+) onto Wyoming montmorillonite.

TL;DR: In this article, the interaction of U(VI) with natural magnetite has been studied using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS).

TL;DR: In this article, the temperature dependence of the Ca isotope fractionation was explained quantitatively by the temperature control on precipitation rates of calcium carbonates in an experimental setting, and this mechanism can in principle also be applied to CaCO 3 precipitation in natural environments in normal marine settings.

TL;DR: In this paper, trace metal clean techniques were used to sample Hawaii Ocean Time-series (HOT) station ALOHA on seven occasions between November 1998 and October 2002, and full water column profile samples were obtained; on the other four occasions, surface and near surface euphotic zone profiles were obtained.

TL;DR: In this article, the magnitude of equilibrium iron isotope fractionation between Fe(H2O)63+ and Fe(O)62+ is calculated using density functional theory (DFT) and compared to prior theoretical and experimental results.

TL;DR: The isotopic composition of dissolved Cu and solid Cu-rich minerals were monitored in batch oxidative dissolution experiments with and without Thiobacillus ferrooxidans.

TL;DR: In this paper, the electron transfer rate for the reactions promoted by the smallest particles is rationalized in the framework of electron transfer theory. But the results in this paper are limited to the case of nanoscale hematite particles with an average diameter of 7.3 nm.

TL;DR: In this paper, the authors present a model of bacterial sulfate reduction that includes equations describing the fractionation relationship between the sulfur and the oxygen isotope composition of residual sulfate (δ34SSO4, δ18OSO4_residual) and the amount of residual sulfur.