Showing papers in "Geochimica et Cosmochimica Acta in 1995"

TL;DR: In this paper, a new calculation of the crustal composition is based on the proportions of upper crust (UC) to felsic lower crust (FLC) to mafic lower-crust (MLC) of about 1.6:0.4.

TL;DR: In this paper, the authors report systematic changes in mudrock composition through time on a single con- tinental cmstal block and show that the changes reflect both sediment recycling processes and changes through time in the composition of crystalline material being added to the sedimentary system and are related to tectonic evolution as the block matures from a series of accreted arc terranes to a stable craton.

TL;DR: In this paper, the authors evaluated the effect of weathering on chemical weathering by correlating variations on solute concentrations and fluxes with temperature, precipitation, runoff, and evapotranspiration (ET) for a worldwide distribution of sixty-eight watersheds underlain by granitoid rock types.

TL;DR: In this article, the thermodynamic equations necessary to characterize the CO2 system in the oceans as a function of salinity and temperature are given, including equations for the dissociation of carbonic acid, boric acid, phosphoric acid and silicic acid.

TL;DR: The conclusion that gammacerane is an indicator for water column stratification, which solves two current enigmas in gammalerane geochemistry, is concluded.

TL;DR: The kinetic and equilibrium fractionation effects for 13C during CO2 gas transfer (ek and eag−g) have been measured in acidified distilled water as mentioned in this paper, and the measured fractionations agreed with earlier work to within 0.2

TL;DR: In this paper, a cross-plot of dibenzothiophene/phenanthrene versus the pristane/phytane ratios measured on seventy-five crude oils from forty-one known source rocks ranging in age from Ordovician to Miocene was presented.

TL;DR: In this article, the carbon isotopic composition of the marine diatom Phaeodactylum tricornutum (δ13Cp) was measured over a series of growth rates (μ) in a continuous culture system in which both δ133CCO2 and [CO2]aq were determined.

TL;DR: UWG-2 is a new garnet standard for oxygen isotope analysis prepared from a single large porphyroblast that was homogeneous (±0.21) at the millimeter-scale before grinding.

TL;DR: In this article, the authors evaluated the effect of climate on chemical weathering by correlating variations in solute con- centrations and fluxes with temperature, precipitation, runoff, and evapotranspiration (ET) for a worldwide distribution of sixty-eight watersheds underlain by granitoid rock types.

TL;DR: In this paper, the competitive and fractional adsorption-desorption of NOM subcomponents were investigated in order to better predict NOM partitioning between the solution and solid phases and, therefore, the transport behavior of the NOM in the subsurface soil environment.

TL;DR: In this paper, the authors measured mineral-aqueous fluid partition coefficients (Dmin/fluid) for U, Th, Pb, Nb, Ba, and Sr in experiments at 2.0 GPa and 900°C.

TL;DR: In this paper, the authors used predicted association constants for rare earth element (REE) complexes to calculate the speciation of the REEs in simulated and natural fluid compositions over ranges of pH, temperature, and pressure.

TL;DR: In this article, a model for oxygen isotope fractionation in body water of terrestrial, herbivorous mammals larger than 1 kg was proposed to estimate the oxygen isotopic composition of intake water in order to reconstruct paleoclimate from the δ 18 O of fossil biogenic phosphate.

TL;DR: In this paper, a model detailing the geometry and coordination of elementary kink sites is presented to explain both the differential incorporation and the rate anisotropy between nonequivalent growth steps on individual {1014} faces.

TL;DR: In this article, the age of the Earth and its relation to the ages of the meteorites were investigated using lead isotope systematics, and the results indicated precise time constraints for the formation of the first planetary objects of the solar system.

TL;DR: In this paper, the authors showed that Gephyrocapsa oceanica can synthesize C 37 C 39 alkenones and esters of di- and tri-unsaturated C 36 fatty acids.

TL;DR: In this article, a new parameter, Λ 6, was introduced to represent lignin, consisting only of the six syringyl and vanillyl phenols and was found to be much less sensitive to diagenetic variation than the commonly used parameter Λ, which includes the cinnamyl phenol component.

TL;DR: In this article, a suite of peridotite xenoliths from kimberlites intruding the Siberian craton indicate the presence of lithospheric mantle over 150 km thick at 350 Ma.

TL;DR: In this paper, the authors show that the As and Se K-edges of free Fe(O, OH)6 octahedra are not supported by the experimental data, and the reason for this discrepancy is due to a mistaken determination by Waychunas et al. (1993) of the AsFe distance of 3.60 A.

TL;DR: In this article, diamond and SiC were found in unmetamorphosed members of all seven chondrite classes and evidence for graphite was found in Orgued (CI) and LL3.1 chondrites.

TL;DR: In this article, diffusion gradients in thin films (DGT) was used to measure in situ fluxes of metals at fine spatial resolution (1.25 mm) in the surface sediments (029 cm) and immediately overlying water of Esthwaite Water, UK.

TL;DR: In this article, the partitioning of rare earth elements (REEs) in calcite overgrowths precipitated from sea-water solutions under steady-state conditions was investigated experimentally using a constant addition technique.

TL;DR: The Guayana Shield is composed of Early to mid-precambrian igneous and metamorphic basement rocks with a quartzitic platform cover as discussed by the authors and the complete absence of limestones and evaporites allows a clear chemical expression in the stream data of the primary weathering of the basement in a humid tropical environment.

TL;DR: In this article, the authors reported high precision (± 0.5%o) potassium isotopic determinations on bulk chondrites, achondrites and lunar samples, on a separated chondrule, and two CAls, and placed stringent limits of ≤52% on the quantity of potassium that could have been lost by partial volatilization.

TL;DR: A series of oxic and anoxic incubations examined the decay of two marine phytoplankton, the diatom Thalassiosira weissffogii and the coccoid cyanobacterium Synechococcus sp, in flow-through systems without macrozooplankton grazers.

TL;DR: In this paper, the authors show that the relatively uniform Sm/Nd ratios in sediments do not indicate a near-constant composition for the upper continental crust of the world.

TL;DR: In this paper, the results of leaching experiments were carried out on twentyone hydrogenetic crust samples from different locations in the central Pacific and the results were compared with four crust and nodule samples of different genetic origin.

TL;DR: In this paper, the authors investigated the possibility that the low MgOSiO2 ratios are due to a different type of alteration, and measured bulk compositions in a suite of peridotites and compared these to their primary compositions, measured where possible or estimated.

TL;DR: X-ray photoelectron spectroscopy (XPS) of an unoxidized surface reveals that sulphur is present as disulphide (S22−, 78 At%), monosulphides (S2−, 15%), and as polysulphite (Sn2−), where 2 < n < 8) As1− predominates, but 15% As0 is also observed.