Showing papers in "Geochimica et Cosmochimica Acta in 2015"

TL;DR: In this article, the results for the preparation and calibration of the U/Pb ratio and isotopic abundances are given, and various sources of uncertainty are discussed and quantified.

TL;DR: This paper measured the U and Mo isotope compositions of euxinic (anoxic and sulfidic) organic-rich mudrocks (ORM) of Member IV, upper Doushantuo Formation, South China.

TL;DR: In this paper, the authors report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world's major rivers.

TL;DR: In this article, the effects of Bacillus subtilis (B.subilis, a typical model bacterium) on the reduction of U(VI) by nanoscale zero-valent iron (nano-Fe 0 ) were investigated using batch techniques.

TL;DR: In this paper, the authors used a thermodynamic model of carbonate speciation to determine the pH of the ocean of Enceladus using data from the Cassini spacecraft.

TL;DR: The IUPAC-IUGS joint Task Group “Isotopes in Geosciences” as discussed by the authors recommends a value of (49.61 − 0.16) Ga for the half life of 87Rb, corresponding to a decay constant λ87 − − 1.3972 − 0.

TL;DR: In this article, the authors analyzed oxygen, carbon and clumped isotopes of a unique set of modern calcitic and aragonitic travertines, tufa and cave deposits from natural springs and wells.

TL;DR: In this paper, a statistical approach to evaluate uncertainties in the calibration of multi-element isotopic tracers has been developed and applied to determining the isotopic composition of mixed U-Pb tracers used for accurate isotope dilution U −Pb geochronology.

TL;DR: In this article, the effects of pressure, temperature, and metallic melt composition on core partitioning were investigated in a multianvil press and diamond anvil cell, up to 100 GPa and 5700 K.

TL;DR: In this paper, the geochemistry of magnetite from the Cretaceous Kiruna-type Los Colorados IOA deposit in Chile has been studied using laser ablation-inductively coupled plasma mass spectroscopy (LA-ICP-MS) transects and electron probe micro-analyzer (EPMA) wavelength-dispersive X-ray (WDX) spectrometry mapping.

TL;DR: In this article, the authors report the bulk mineralogies and degree of hydration in 37 different carbonaceous chondrites: Renazzo-like, Mighei-like and ungrouped (type 2) samples.

TL;DR: In this paper, Li isotope composition of river-borne dissolved and solid material in the largest River system on Earth, the Amazon River basin, was analyzed to characterize Li isotopes fractionation at a continental scale.

TL;DR: In this paper, the double spike technique and a new data reduction method were used to analyze an array of seawater samples and 41 geostandards covering a broad range of geological settings relevant to low and high temperature geochemistry.

TL;DR: In this article, an automated in situ instrumentation captured high-resolution surface water pCO2, CH4 and 222Rn data at the creek mouth, and ∼500m upstream in a sub-tropical mangrove ecosystem (Southern Moreton Bay, Australia, S27.78°, E153.38°) over a spring-neap-spring tidal cycle (∼15 days) during November 2013.

TL;DR: In this paper, International Simple Glass (ISG) was altered at 90°C in a solution initially saturated with respect to amorphous 29SiO2, and the pH was raised to 11.5 after 209d by the addition of KOH.

TL;DR: In this paper, a manipulation experiment was conducted to determine the influence of organic C and NO3− loading on partitioning of sediment thin discs in large aquarium tanks with filtered, N2/CO2 sparged seawater to maintain O2 limited conditions.

TL;DR: In this paper, a clumped-isotope-based geothermometer was used to quantify the relative amounts of biogenic vs. thermogenic gases in the Antrim Shale indicating a larger proportion of thermogenic gas in the system than previously thought.

TL;DR: In this paper, a new Δ47-T calibration was proposed for carbonate clumped isotope thermometry, which is based on the temperature-dependent abundance of the rare 13C-18O bonds in carbonate minerals, specified as a Δ47 value.

TL;DR: In this paper, the congruent dissolution of borosilicate glass is explained by a process that is spatially and temporally coupled to the precipitation and growth of an amorphous silica layer at an inwardly moving reaction interface.

TL;DR: In this paper, the effect of water on the sulfur concentration at sulfide saturation (SCSS) in basaltic, andesitic, and rhyolitic melt compositions at 1250°C, 1 GPa, and oxygen fugacities buffered at, or near, the graphite-carbon dioxide (CCO) buffer in a piston-cylinder apparatus was investigated.

TL;DR: Yang et al. as discussed by the authors studied the origin of low δ26Mg basalts and evaluated whether Mg isotope ratios of basalts can be used to trace deeply recycled carbon, high-precision major and trace element and mg isotopic analyses on the Cenozoic alkaline and tholeiitic basalts from the South China Block, eastern China.

TL;DR: In this article, the authors determined pore fluid rare earth element (REE) concentrations in near-surface sediments retrieved from the continental margin off Oregon and California (USA) and used their measurements to estimate the diffusive flux of Nd out of ocean sediments.

TL;DR: In this article, the authors analyzed sulfide samples from 27 black smoker samples derived from three different seafloor hydrothermal fields: the ultramafic-hosted Logatchev Hydrothermal field on the Mid-Atlantic Ridge, the basaltic-based Turtle Pits field and the felsic hosted PACMANUS field in the Manus basin (Papua New Guinea).

TL;DR: In this paper, the authors presented seawater dissolved Fe, Zn and Cd concentration and stable isotope ratio (δ56Fe, δ66Zn, and δ114Cd) profiles from two stations in the Pacific Ocean, the SAFe Station (30°N 140°W) in the subtropical North East Pacific from the GEOTRACES IC2 cruise, and the marginal San Pedro Basin (33.8°N 118.4°W).

TL;DR: In this paper, the authors show that the solubility of Nb2O5 (solid) in aqueous fluids increases with increasing HF concentration, but is not strongly affected by temperature.

TL;DR: In this paper, the role of reduced iron (Fe) phosphate mineral vivianite (Fe(II)3(PO4)*8H2O) has been quantified in marine sediments by combining the SEDEX method with microscopic and spectroscopic techniques such as micro X-ray fluorescence (μXRF) elemental mapping of resin-embedded sediments, as well as scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) and powder Xray diffraction (XRD).

TL;DR: In this article, electron microprobe analyses and oxygen three-isotope measurements by high precision secondary ion mass spectrometry on 45 type I (FeO-poor) chondrules/fragments and 3 type II chondrule fragments from Meteorite Hills 00426 and Queen Alexandra Range 99177, two of the most primitive CR3 chondrites.

TL;DR: In this paper, the authors examined mineralogical, chemical and isotopic evidence on the temperatures, timing, and fluid compositions involved in the formation of this listvenite, which can provide insight into processes including (a) carbon fluxes at the leading edge of the mantle wedge in subduction zones and (b) enhanced mineral carbonation of peridotite as a means of carbon storage.

TL;DR: The martian meteorite Northwest Africa (NWA) 7034 was examined both petrographically and geochemically using several micro-beam techniques including electron probe microanalysis and secondary ion mass spectrometry.