Showing papers in "Geochimica et Cosmochimica Acta in 2007"

TL;DR: In this paper, the relative distribution of soil-derived GDGT membrane lipids can be used in palaeoenvironmental studies to estimate past annual mean air temperature and soil pH.

TL;DR: In this article, a set of correlations describing the phase stability relations in the system H 2 O-NaCl is developed, including the vapor pressure of halite and molten NaCl, the NaCl melting curve, the composition of a halite-saturated liquid and vapor, the pressure of vapor+ liquid+halite coexistence, the temperature-pressure and temperature-composition relations for the critical curve, and the compositions of liquid and vapour on the vapor+liquid coexistence surface.

TL;DR: In a survey of the elemental and isotopic compositions of insoluble organic matter (IOM) from 75 carbonaceous, ordinary and enstatite chondrites, this article found dramatic variations within and between chondrite classes.

TL;DR: In this article, a numerical alteration sequence for CM chondrites is proposed, which is based on the existing scheme of Browning et al. The proposed sequence is more comprehensive and employs petrologic subtypes that are easier to use and remember than mineralogic index values.

TL;DR: In this paper, the authors presented Early Cretaceous (143-129 Ma, new Sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb ages) adakitic granites, which are directly associated with a contemporary metamorphic core complex.

TL;DR: In this paper, the authors used first-principles vibrational frequency and electronic structure calculations to estimate stable isotope fractionations of mercury and thallium for molecules, atoms and ions.

TL;DR: This article showed that simple sorption reactions do not stabilize the bulk of soil organic carbon in most mineral soils and pointed instead to stabilization to other mechanisms such as organo-Fe complexes or ternary associations among Fe oxides, OM and other minerals.

TL;DR: In this article, the effect of precipitation rate on the oxygen isotope fractionation between aragonite and water was almost within the analytical error of ±� 0.13 ǫ and thus insignificant.

TL;DR: In this paper, the fine-grained Nd-Sr isotopes of the 10 major deserts and sandy lands in North China and the loess in Chinese Loess Plateau were systematically investigated.

TL;DR: In this paper, the authors studied the biodegradation of OM bound to goethite (α-FeOOH), pyrophyllite, and vermiculite via specific mechanisms as estimated from OC uptake in different background electrolytes and operationally defined as 'ligand exchange', 'Ca2+ bridging', and 'van der Waals forces'.

TL;DR: In this paper, the mobilization of arsenic (As) to the groundwater was studied in a shallow Holocene aquifer on the Red River flood plain near Hanoi, Vietnam.

TL;DR: In this paper, a series of pyrite oxidation experiments in the laboratory were conducted under aerobic conditions by using O2 as an oxidizing agent and under anaerobic conditions using dissolved Fe(III)aq as oxidant with varying δ18OH2O values in the presence and absence of acidithiobacillus ferrooxidans.

TL;DR: In this paper, peridotitic xenoliths from the Cretaceous (∼100 ǫ) Fuxin basalts at the northern edge of the craton have been integrated with data from other localities across the region to provide an overview of the processes involved.

TL;DR: In this paper, a set of correlations for the volumetric properties and enthalpies of phases in the system H2O-NaCl as a function of temperature, pressure, and composition has been developed that yields accurate values from 0 to 1000°C, 1 to 5000 bar, and 0 to 1 XNaCl.

TL;DR: In this paper, high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity.

TL;DR: In this article, a re-evaluation of calcite-water oxygen isotopic fractionation factor may be in order, based on several lines of evidence indicate that the geochemical environment of Devils Hole has been remarkably constant for at least 10 years.

TL;DR: In this paper, Fourier transformed infrared (FTIR) spectroscopy was used to characterize arsenate-ferrihydrite sorption solids synthesized at pH 3-8.

TL;DR: In this paper, a simple interionic potential developed to describe the nine component system K2O-Na2O−CaO−MgO−FeO-Fe3−Al2O3−TiO2-SiO2 (KNCMFATS) was implemented into a molecular dynamics simulation code and a key feature of the simulation is to make the link between macroscopic properties of the melt and its microscopic structure and dynamics.

TL;DR: In this article, a new and empirical viscosity equation for anhydrous and hydrous natural silicate melts has been developed using the following formulation:======¯¯¯¯¯¯¯¯¯¯¯¯¯¯

TL;DR: In this paper, a steady state model was proposed for explaining Ca isotope fractionation across the observed precipitation rate range of ∼14 orders of magnitude, where the relative balance between attachment and detachment fluxes at the calcite crystal surface was assumed to be a function of diagenesis.

TL;DR: In this paper, the authors investigated changes in soil charcoal particle morphology and chemical composition using surface area analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, chemical oxidation, and 13C NMR analysis.

TL;DR: In this paper, the authors characterized the oxidation state and mineral phase association of Co, Ce, and Pb in hydrogenetic, diagenetic, and hydrothermal marine ferromanganese oxides.

TL;DR: Authigenic framboidal and massive pyrite (median values 1500 and 3200 ppm As, respectively), is the principal arsenic residence in sediment from both boreholes.

TL;DR: The authors measured the Li isotope ratios of a range of coexisting phases from peridotites and mafic magmas to investigate high-temperature fractionations of 7Li/6Li.

TL;DR: In this article, the authors show that the high field strength elements Ti, Nb, and Ta were mobilized and thereby fractionated from Zr and Hf during the dehydration process that transformed blueschist into eclogite.

TL;DR: In this article, major, trace and organic elements of a laterite profile developed on Neogene basalts in northern Hainan Island, South China were reported, the aim of which was to investigate element mobilization and re-distribution during extreme weathering.

TL;DR: In this paper, the role of mineral reaction rates on changes in fluid chemistry and mineralization processes in ultramafic-hosted hydrothermal systems has been investigated using experimental and theoretical data for mineral dissolution rates.

TL;DR: The analysis of micro-inclusions in fibrous diamonds from the Diavik mine, Canada revealed the presence of high density fluids (HDFs) that span a continuous compositional range between carbonatitic and saline end-members as mentioned in this paper.

TL;DR: In this article, four very depleted spinel-harzburgites from the Lherz massif (France) have been analyzed for HSE in whole-rock and in major mineral separates by isotope dilution.

TL;DR: In this article, the authors present data from all four sulfur isotopes that suggest that the internal fractionations associated with the sulfate reduction network are larger than previous estimates, and they construct a model of a traditional SRC network, as well as a more recent incarnation of the SRC with multiple sulfur intermediates.