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Showing papers in "Geochimica et Cosmochimica Acta in 1978"


Journal ArticleDOI
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.

5,562 citations


Journal ArticleDOI
TL;DR: In this article, 15 chondrites, including eight carbonaceous chondites, were analyzed for rare earth element abundances by isotope dilution, and the persistence of anomalies in chondritic materials relatively removed from direct condensational processes implies that anomalous components were introduced at a late stage of chondrite formation.

1,346 citations


Journal ArticleDOI
TL;DR: In this paper, the absolute concentration of steranes, terpanes, and paraffins (n + iso) in combination with internal ratios of individual biomarkers such as primary/secondary terpane, 17α(H)-trisnorhopane/18α( H)-triscope II (both maturation specific), 5β/5α-steranes, 5β-sterane/17α (H)-hopanes and rearranged steranes/5β-teranes (all migration oriented), 5α/ 5α-stanes and

1,186 citations


Journal ArticleDOI
TL;DR: The qualitative PAH pattern is remarkably constant for most of the locations studied, and the quantitative PAH abundance increases with proximity to urban centers as discussed by the authors, consistent with anthropogenic combustion's being the major source of these compounds.

943 citations


Journal ArticleDOI
TL;DR: In this paper, it was demonstrated that differences in the Ca/^(44)Ca ratio due to mass dependent isotope fractionation in nature are clearly resolvable to a level of 0.001.

892 citations


Journal ArticleDOI
TL;DR: Experimental techniques for examining trace element behavior are reviewed in this paper, and applications of these techniques are described for a variety of partition coefficients including: olivine/liquid, subcalcic pyroxene/ liquid, calcic pyrosene/liquid and perovskite/liquid.

623 citations


Journal ArticleDOI
TL;DR: In this paper, the sulphur isotopic composition of ocean water sulphate was determined using the SF 6 method for samples from various depths of the Geosecs Stations II and 3 and for a single Pacific Ocean surface sample.

582 citations


Journal ArticleDOI
TL;DR: In this article, fresh mid-ocean ridge basalt of varying crystallinity has been powdered and reacted with seawater and an artificial Na-K-Ca-Cl solution at 200-500°C and 500-1000 bar in sealed gold capsules.

463 citations


Journal ArticleDOI
TL;DR: Trace element analyses have been carried out on hydrothermally altered pillow basalts of greenschist facies dredged from the median valley of the Mid-Atlantic Ridge as mentioned in this paper.

425 citations


Journal ArticleDOI
TL;DR: In this paper, an isotopic exchange between quartz and water, using a novel technique, yielded an equilibrium fractionation Δ18 = 9.0 at 250°C and 15 kbar, where the reaction proceeds predominantly by solution of fine grains and growth of larger grains.

362 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the abundance of rare earth elements, Hf, Sc, Co, Cr and Th in garnet megacrysts and their volcanic hosts or matrices to estimate garnet/liquid partition coefficients for these elements.

Journal ArticleDOI
TL;DR: In this article, the authors showed that methanogenesis and sulfate-reduction occurred simultaneously in sediments incubated under N2, thereby indicating that the two processes are not mutually exclusive.

Journal ArticleDOI
TL;DR: In this paper, the influence of a silicate liquid structure on mineral-liquid partitioning was evaluated for coexisting anhydrous immiscible granitic and ferrobasaltic magmas.

Journal ArticleDOI
TL;DR: In this article, the partitioning behavior of cerium, europium, gadolinium, and ytterbium between an aqueous vapor phase and water saturated silicate melt have been experimentally examined using a new experimental approach employing radioactive tracers and a double-capsule technique.

Journal ArticleDOI
TL;DR: In this article, a theoretical treatment of the evolution of the carbon isotopes C13 and C14 in natural waters and in precipitates which derive from such waters is presented, where the effects of an arbitrary number of sources and sinks (such as mineral precipitation, CO2 degassing and production of methane), and of equilibrium fractionation between solid, gas and aqueous phases are considered.

Journal ArticleDOI
TL;DR: In this article, a method for quantitative analysis of silicates with an ion-microprobe has been developed by suppressing the intensities of interfering molecular ion species based on the difference in the kinetic energy distributions between molecular and single-atom ions.

Journal ArticleDOI
TL;DR: In this article, geochemical evidence for modern low-temperature serpentinization has been found in three new localities, and it was suggested that the low temperature reactions are a common mode of formation of the lizardite-chrysotile and brucite assemblage.

Journal ArticleDOI
TL;DR: In this paper, the same equations for partial melting and crystallization of trace elements were used to model major elements in a way similar to the quantitative petrogenetic modelling used for trace elements, however, modelling with major elements is constrained by the stoichiometry of the solid phases.

Journal ArticleDOI
TL;DR: The Pb and Sr isotope ratios of Plio-Pleistocene volcanic rocks from the Aleutian volcanic arc are used as tracers of the lithospheric subduction process at the converging Pacific and Bering plates.

Journal ArticleDOI
TL;DR: In this article, the authors show that the Azores mantle plume is 10 to 30 times enriched in LIL elements with very small (⪢ 0.1 < D < 1) bulk crystal/melt partition coefficients (Rb, Cs, Ba, La).

Journal ArticleDOI
TL;DR: In this paper, the authors measured the 18 O/16 O gradient inward from the feldspar surface using an ion microprobe, and fitting a solution of the diffusion equation to the data.

Journal ArticleDOI
TL;DR: In this article, measurements of nutrients and trace metals were used to examine the processes controlling their distributions in the interstitial waters of Saanich Inlet, and the results showed that porosity, organic carbon and sedimentation rate by 210Pb were used in conjunction with the nutrient measurements to test the equation for the diagenesis of organic matter in fine-grained, organic-rich and rapidly accumulating sediments.

Journal ArticleDOI
TL;DR: The influence of microbial degradation during deposition of organic matter is intense in the stratigraphically lowest zone and decreases toward younger beds, where fossil molecules derived from higher plants, algae and other planktonic organisms and bacteria are abundant as discussed by the authors.

Journal ArticleDOI
TL;DR: In this paper, a petrogenetic grid for plagioclase, spinel- and garnet-lherzolite analogues in the system CaO-MgO-Al2O3-SiO2 is presented from 1 bar to 30 kbar and 400 to 1500°C.

Journal ArticleDOI
TL;DR: In this paper, the molecular compositions and stable carbon and hydrogen isotope fractionations associated with the production of lower-molecular-weight hydrocarbons by pyrolysis of normal octadecane were determined as a function of time, temperature and catalysis.

Journal ArticleDOI
TL;DR: In this article, the chemistry of orthophosphate uptake from synthetic seawater onto the surfaces of synthetic calcite, aragonite and low-magnesium biogenic calcite has been studied, in order to elucidate the kinetics of the process.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the Fe and Mg distribution between coexisting olivine and lunar basaltic liquids produced by equilibrium partial melting of natural lunar samples and found that the distribution coefficients of the conventional distribution coefficients are nearly linear functions of inverse temperature, and the exchange coefficient is nearly independent of temperature and composition within a given magma group.

Journal ArticleDOI
TL;DR: In this paper, mass spectrometric analyses of phenocrysts, containing glass-vapor inclusions quenched in glassy rims of tholeiitic submarine pillow basalts from spreading centers and Hawaii, indicate that water released from the inclusions upon thermal decrepitation is much less than is released from equivalent volumes of the matrix glass enclosing the same phenocryst.

Journal ArticleDOI
TL;DR: The authors showed that melanoidin formation may be favored in marine environments where basic amino acids should preferentially condense with sugars to form nitrogen-rich polymers that have a great affinity for clay mineral surfaces.

Journal ArticleDOI
TL;DR: The concept of pressure solution does not contradict any thermodynamic principle; in particular, it does not require that the chemical component of the solid have a smaller partial volume in solution than in the solid state.