Showing papers in "Geochimica et Cosmochimica Acta in 2014"

TL;DR: In this paper, the authors present direct experimental measurements of D PGE sul, based on in situ microanalysis of the sulfide and silicate melt, with values ranging from ∼4.5 × 105 (Ru) to ∼2.3 × 106 (Ir, Pt) and they use their new set of partition coefficients to develop a fully constrained model of PGE behavior during melting which accurately predicts the abundances of PME in mantle-derived magmas and their restites, including mid-ocean ridge basalts, continental picrites, and the parental magmas

TL;DR: In this paper, the authors explored the fundamental factors controlling Au and As ratios in arsenian pyrite from ore deposits using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses.

TL;DR: In this article, the authors quantified the fractional abundance of 6-methyl brGDGTs in globally distributed soils and showed that they are abundant components, comprising on average 24% of the total amount of brDGTs.

TL;DR: In this article, the retention of uranium (U(VI) and europium (Eu(III) onto well-characterized sepiolite was elucidated by using microscopic adsorption, spectroscopic techniques and surface complexation modeling.

TL;DR: A Bayesian regression approach is developed and applied to the TEX86–SST calibration that explicitly allows for model parameters to smoothly vary as a function of space, and considers uncertainties in the modern SSTs as well as in the T EX86-SST relationship.

TL;DR: In this article, the most comprehensive molecular dataset of 197 Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses from solid-phase extracted marine DOM covering two major oceans, the Atlantic sector of the Southern Ocean and the East Atlantic Ocean (ranging from 50° N to 70° S).

TL;DR: In this paper, the authors investigated the biogeochemical cycling of copper (Cu) and zinc (Zn) isotopes in the ocean and presented estimates for the isotopic composition of the inputs to the oceans based on new data presented here and published data.

TL;DR: In this paper, the applicability of the revised Helgeson-Kirkham-Flowers (HKF) equations of state for aqueous species was extended to 60kb by developing estimates of ( e H 2 O ).

TL;DR: In this paper, an experimental study was conducted to determine oxygen and carbon isotope fractionation factors in the system dolomite-water-CO2 at 80-350 and 100-250°C, respectively, by means of direct precipitation (80-°C) and dolombization of CaCO3 (100-350°C).

TL;DR: In this paper, the authors reported the values of reduced partition function ratios for Fe, Ni, Cu, and Zn bound to a number of inorganic and organic ligands.

TL;DR: In this article, the authors studied the distribution of branched glycerol dialkyl tetraethers (brGDGTs) lipids in suspended particulate matter (SPM) of the Yenisei River.

TL;DR: Passey et al. as mentioned in this paper used a combination of laboratory and natural geological experiments on Paleozoic brachiopod shells to directly observe rates of 13 C − 18 O bond reordering.

TL;DR: In this paper, the authors studied the seasonal turnover and marine and terrestrial sources of DOM in an intertidal creek bank of the southern North Sea down to 3m depth and link the biogeochemical processes to FT-ICR-MS data and the analyses of inorganic porewater chemistry, δ 13 C of solid-phase extracted dissolved organic carbon (SPE-DOC), dissolved black carbon (DBC), and dissolved carbohydrates (DCHO).

TL;DR: In this article, an integrated mineralogical and geochemical study was carried out on typical sphalerite (ZnS) samples from the main Ge deposit in western Europe: the vein-type Zn-Ge-Ag-(Pb-Cd) deposit of Noailhac- Saint-Salvy (Tarn, France).

TL;DR: This paper examined the molecular and isotopic signatures of dissolved organic matter (DOM) along with its biolability in glacier ice, glacier-fed streams, and alpine lakes on the Tibetan Plateau.

TL;DR: In this paper, the authors investigated the role change of Na+ cations from network modifier to charge compensator in the presence of Al3+ ions and showed that the configuration entropy of the configurational entropy at the glass transition temperature is strongly nonlinear, with sharp increases and decreases depending on the Al/(Al+Na) ratio.

TL;DR: The Paris chondrite as discussed by the authors provides an excellent opportunity to study CM chondrules and refractory inclusions in a more pristine state than currently possible from other CMs, and to investigate the earliest stages of aqueous alteration captured within a single CM bulk composition.

TL;DR: In this article, the authors reported co-occurrence of low-Ti (TiO 2 2 ǫ> 2 ¼ ) types of lamprophyres in the Jiaodong Peninsula, eastern North China Craton in order to address this issue.

TL;DR: In this article, a postcollisional potassium-rich magmatism in southern Tibet provides an important insight into the deep processes inducing accelerated plateau uplift and associated geologic episodes during early Miocene.

TL;DR: In this article, the authors explored the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks and found that increased Mn concentrations in apats correlate with decreasing Fe2O3 (Fe3+) and Mn in the whole-rock and likely reflect increased Mn2+/Mn3+ and greater compatibility of Mn2+, relative to Mn3+ in apatis under reduced conditions.

TL;DR: In this article, the authors demonstrate that adsorption of Zn to poorly crystalline Mn oxyhydroxide results in preferential association of heavier isotopes with the sorbent phase, and they infer that Zn adsorbs first as tetrahedral, innersphere complexes at low surface loading, with preferential incorporation of heavy isotopes relative to the octahedral Zn species predominating in solution.

TL;DR: In this paper, a local Chinese calibration of the MBT-CBT proxy and an alternative temperature proxy for use in semiarid and arid regions based on the fractional abundances of bGDGTs was proposed.

TL;DR: In this article, the influence of aqueous alteration on the morphology, isotopic signature, molecular structure, spatial distribution, and mineralogical environment of the organic matter within the matrices of three carbonaceous chondrite falls, Renazzo (CR2), Murchison (CM2), and Orgueil (CI), was investigated.

TL;DR: In this article, the relationship between cesium (Cs) adsorption on clay minerals with various expandabilities and Cs mobility in environment was investigated using sequential extraction, batch adaption, X-ray diffraction (XRD), generalized adsorptions model (GAM), and C-s LIII-edge extended Xray absorption fine structure (EXAFS) analyses with molecular simulations using the density functional theory (DFT).

TL;DR: In this article, an inverse modeling of apatite U-Pb dates was used to produce theoretical t −T solutions assuming Pb was lost by volume diffusion. But the results of this study were challenged by independent geological constraints and intra-grain U-pb dates, which demonstrate that volume diffusion governed the displacement of Pb.

TL;DR: Zn concentration and isotope data for seawater samples from the Atlantic sector of the Southern Ocean, collected during the IPY/GEOTRACES ANT-XXIV/III cruise along the Greenwich Zero Meridian Data are reported for the full depth range of the water column at three stations, as well as a transect of surface samples, using a new analytical approach as mentioned in this paper.

TL;DR: In this article, the authors explore the potential for non-traditional isotope systems to fingerprint diagenesis, to quantify the extent to which geochemical proxies are altered during diagenogenesis, and to investigate the importance of diagenisation within the global Ca and Mg geochemical cycles.

TL;DR: In this paper, the reaction of organic matter (OM) to post-synthesis Fe oxide (Fe oxide) versus coprecipitation (formation of Fe oxides in presence of OM) was studied.

TL;DR: In this paper, the effect of metabolic state on the composition of intact polar and core lipids and the resulting TEX86 paleothermometer in pure cultures of the marine AOA Nitrosopumilus maritimus as a function of growth phase was investigated.

TL;DR: In this article, elemental and isotopic data detailing how the Mg isotope system behaves in natural and experimentally synthesized clay minerals is presented, and it is shown that the bulk mg isotopic composition (δ 26 Mg) of a set of natural illite, montmorillonite and kaolinite spans a 2' range, and that their isotope composition depends strongly on a balance between the relative proportions of structural and exchangeable mg.