Showing papers in "Geochimica et Cosmochimica Acta in 1986"

TL;DR: In this paper, the carbon and hydrogen stable isotope composition of the methane as a function of the coexisting carbon dioxide and formation water precursors is used to distinguish two primary methanogenic pathways.

TL;DR: In this paper, an empirically derived relationship between the chemical composition of a carbonate in the CaCO3-(Ca, Mg)(CO3)2-FeCO3 system and the function 103 In α at 100°C is 103 ∆ α = 8.94XCaCO3 + 9.29XMgCO3+ 8.77XFeCo3 where Xi is the mole percent of component i in the carbonate.

TL;DR: In this article, the dissolution kinetics of slightly soluble oxides and silicates are controlled by chemical processes at the surface, and the reaction controlling steps can be interpreted in terms of a surface coordination model.

TL;DR: In this article, rate laws for the aqueous oxidation of pyrite by ferric ion, dissolved oxygen and hydrogen peroxide at 30°C in dilute, acidic chloride solutions were derived.

TL;DR: The dissolution of goethite and other iron oxides is kinetically controlled by the detachment of an Fe center from the surface as discussed by the authors, which may occur either by direct reduction, subsequent to the adsorption of reductants, or, indirectly by electron transfer from dissolved Fe(II) ions which are generated by the same reductant in solution.

TL;DR: Evaluating a kinetic isotope effect involving 15N, during the transamination reactions catalyzed by glutamic oxalacetic transaminase, finds that during the transfer of amino nitrogen from glutamic acid to oxaloacetate to form aspartic acid, 14NH2 reacted 1.0083 times faster than 14 NH2.

TL;DR: The radioisotope 10Be has been used as a tracer to evaluate subduction and recycling of sediments in island arcs as mentioned in this paper, and it is especially suitable for monitoring sediment subduction.

TL;DR: The dissolution rate of albite has been measured as a function of pH and time at 25°C and 70°C in a single-pass flow-through leaching apparatus as mentioned in this paper.

TL;DR: In this article, the authors combined trace element and isotope studies of 319 brachiopods, covering the Ordovician to Permian time span, show that δ13C and δ18O in well preserved specimens varied during the Paleozoic.

TL;DR: In this article, the degradation of radiolabelled membrane lipids from a methanogenic bacterium and a pseudomonad were investigated in mangrove, beach and high marsh marine sediments under aerobic and anaerobic conditions.

TL;DR: In this article, the authors measured 87 Sr 86 Sr, 13 C 12 C, 18 O 16 O and 15 N 14 N ratios and Sr concentrations in modern and prehistoric (610 to 5470 yr old) bones of animals with marine or terrestrial diets from Greenland.

TL;DR: In this paper, the authors investigated the interaction of equigranular peridotites with seawater and seawater derived solutions at 200°C and 300°C, 500 bars and found that the reaction rates of olivine to enstatite to be approximately 1.5:5:1 (moles per unit time per unit surface area).

TL;DR: In this article, in situ measurements with a benthic flux chamber, in which dissolved oxygen and pH were maintained near ambient values (regulated flux-chamber), showed that the sediment did not release any of these ions but instead removed Co, Mn, Co, and Fe from the overlying water.

TL;DR: In this article, a model based on the in situ physiological characteristics of methanogens and sulfate reducers was developed to predict the relative importance of sulfate production and reduction in lakes of various trophic status.

TL;DR: The chemical equilibrium model of Harvie et al. as mentioned in this paper has been extended to include borate species and is valid to high ionic strength (≈14 m) and high borate concentration.

TL;DR: The pH-dependent precipitation of pyrite and marcasite may be caused by electrostatic interactions between polysulfide species and pyrites or marcasites growth surfaces as discussed by the authors.

TL;DR: Pb, Nd and Sr isotopic compositions are reported for ultrapotassic rocks from a variety of tectonic settings and suggest derivation of leucitites from sources which have been variably contaminated by either the hotspot which initiated volcanism or during earlier enrichment events as discussed by the authors.

TL;DR: In this article, the solubility constant of Henry's law has been experimentally determined in a tholeiitic basalt melt and the data permit calculation of the distribution of noble gases between a melt and coexisting vesicles.

TL;DR: In this paper, the concentrations of organic carbon (C) and pyrite sulfur (S) in over 600 samples of Cambrian to recent normal marine shales have been obtained, from their own chemical analyses and from the literature.

TL;DR: In this article, the authors examined the Nd isotope data for heterogeneity of the Archean mantle and the Sm/Nd depletion of the mantle, and the correlation between SiO2 content and Nd values was considered.

TL;DR: The LoNd array is defined by basalts from Tubuaii, St Helena, New England Seamounts, Comores, San Felix and Walvis Ridge.

TL;DR: In this paper, the solubilities of oxides in H2O and CO2 fluids in equilibrium with peridotites and with several single minerals have been determined at 15-20 kbar pressure and 600-1100°C.

TL;DR: The isotope systematics in these inclusions are sufficiently similar to those of a modern evaporite pan to indicate that Permian sea water was isotopically similar to modern sea water.

TL;DR: In this paper, the same pattern of refractory lithophile elements in chondrites and planets was found in the Earth, the Moon and achondritic meteorites, and it was argued that the relative abundances of these elements are chondritic in the bulk Earth.

TL;DR: Pore water profiles of uranium and thorium isotopes in the muddy sediments of Buzzards Bay, MA permit an assessment of the effect of diagenetic redox reactions on the geochemical behavior of these elements as mentioned in this paper.

TL;DR: Amorphous kerogens from Phanerozoic sedimentary rocks may be divided into two groups on the basis of their δ13C values as discussed by the authors, i.e., h-amorphous and l-morphous.

TL;DR: In the Central Pennine Region of England, three different types of concretions (calcite/pyrite, dolomite, pyrite and siderite) occurring spatially quite close together in the central Pennine region of England vary widely in carbon isotope composition (+10.35% >δ13C > −21.49% as mentioned in this paper.

TL;DR: In this paper, the shock history of the Shergotty meteorite has been evaluated by analyzing the observable shock effects, including mosaicism, deformation bands, planar fractures, and mechanical twin lamellae in clinopyroxene.

TL;DR: In this article, the oxygen isotope data for the chert-phosphate pairs were used to calculate the temperatures of the formation of the phanerozoic and the waters in which they equilibrated.

TL;DR: In this paper, the authors show that the REE composition of the hydrothermal component is primarily acquired via scavenging from seawater, and conclude that the residual energy of the sediment is derived from the interaction of seawater and Fe in the plume.