Showing papers in "Geochimica et Cosmochimica Acta in 1976"

TL;DR: In this paper, a new approach to estuarine studies is presented which establishes 1) the extent and salinity dependence of non-conservative behaviour; 2) composition and chemical form of removal products; and 3) abiological removal mechanisms.

TL;DR: In this paper, measurements on 170 carbonate rocks show decreasing δO 18 of similar magnitude for both limestones and dolomites over a time span of ~ 2800 m.y.

TL;DR: For the mica-water and amphibole-water systems, the hydrogen isotope fractionation factor was determined at temperatures ranging between 400 and 850°C as mentioned in this paper, where m is the molar fraction of the six-fold coordinated cations in the crystal, regardless of mineral species.

TL;DR: A suite of Australian shales, greywackes and subgreywacks ranging in age from Proterozoic to Triassic were analyzed for the rare earth elements (REE) in order to detect any secular changes in rare earth distribution.

TL;DR: In this paper, the lignin oxidation products and 13C/12C ratios were compared as indicators of land-derived organic matter in surface sediments from the western Gulf of Mexico.

TL;DR: In this paper, the authors propose a method for the detection of asteroids in the Earth and Planetary Sciences (EPSS) domain. Ph.D., Massachusetts Institute of Technology.

TL;DR: In this paper, a suite of samples from the central and western United States were used to determine the hydrogen and oxygen isotopic compositions of the cherts and showed that the change with time of the isotopic composition of cherts can be satisfactorily explained in terms of past climatic temperature fluctuations.

TL;DR: The dissolution kinetics of 5% by weight suspensions of two potassium feldspars and six plagioclases were studied for 400-1200 hr at 1 atm PCO2 as discussed by the authors.

TL;DR: The sterol contents of plankton and sediment samples have been determined as mentioned in this paper, showing that 34% of the sterols in the Gulf sediments are derived from terrigenous sources.

TL;DR: The 87Sr86Sr ratio in sea water has varied over geologic time due to the addition of strontium to the sea from rocks with a variety of ratios as mentioned in this paper.

TL;DR: The abundance of 15N in particulate organic matter in the euphotic layer of the North Pacific Ocean was investigated in this paper, where the 15N values ranged from −1.7 to +9.7% relative to atmospheric nitrogen.

TL;DR: Atomic emission spectrographic analysis of the trace inorganic constituents of marine humic substances gave the following range of concentrations: Si, 200 ppm to > 2%; Al, 400 ppm to ~ 1%; Fe, 600-3000 ppm; Ca, 600 ppm to < 2%; Mg, 20-6000 ppm; Na, 6-600 ppm; Ag, < 6-500 ppm; B, < 60-1000 ppm; Cu, 600−4000 ppm; Mn, 8-100 ppm; Mo, <20-3000 Mbps; Ni, 100-1000 Mbps;

TL;DR: In this paper, the isotopic composition of Pb and Sr and the abundances of Rb, Sr, U, Th, and Pb were determined for whole rock samples from all major volcanic centres of the Cenozoic alkaline volcanism of Central and South Italy, together with some samples from the contemporaneous anatectic Tuscan volcanism.

TL;DR: In this paper, it is suggested that hydrated cations, including Co2+ ions, are initially adsorbed on to the surfaces of certain Mn(IV) oxides in the vicinity of essential vacancies found in the chains or sheets of edge-shared [MnO6] octahedra.

TL;DR: The extent of hydrogen and oxygen isotope exchange between clay minerals and water has been measured in the temperature range 100-350° for bomb runs of up to almost two years as mentioned in this paper.

TL;DR: In this article, a simple but precise computer program (WATMIX) has been developed for calculating mixture composition for closed and open system mixing of arbitrary end-members, which allows one to isolate three important processes leading to non-linear behaviour: the algebraic effect, the δPCO2 effect, and the ionic strength effect.

TL;DR: In this paper, surface concentrations of reactant and product species have been calculated from bulk fluid data using mass transport theory and a model that accounts for homogeneous reactions in the bulk fluid.

TL;DR: In this article, the Sr isotopic composition of seawater was measured on carbonate rocks and a composite pattern during geologic history was shown. But the trend closely resembles the K2O/Na2O secular variations in composition of igneous and sedimentary rocks and probably reflects the fractionation state of the contemporary crust.

TL;DR: Oxygen isotope ratios were determined for quartz, magnetite, ankerite, siderite, riebeckite, hematite and talc in samples of banded iron-formation from the Dales Gorge Member of the Brockman Iron Formation.

TL;DR: In this article, new trace element analyses have been made on the composite Canadian Precambrian shield samples reported in 1967 and the overall mean abundance of Cr has been revised to 35 ppm (from 99).

TL;DR: The results from gas chromatography of 60 recent sediment and 10 benthic algae samples delineate two distinct shelf environments in the northeastern Gulf of Mexico as mentioned in this paper, indicating a terrigenous hydrocarbon source.

TL;DR: In this paper, a fundamental rate equation for the dissolution of calcite in a pure 0.7 M KC1 solution has been determined, where the reaction rate is pH independent above pH = 7.5.

TL;DR: The Khtada Lake in British Columbia, Canada is a metamorphic complex consisting of high grade amphibolite and metasedimentary units with development of gneiss, migmatite and homogeneous autochthonous plutons.

TL;DR: In this paper, the major ions and P, Fe, Mn, pS, pϵ and pH were measured in interstitial waters of cores from eutrophic Greifensee in north-central Switzerland.

TL;DR: Carbon isotope measurements carried out on 67 dolomite samples from the Middle Precambrian Lomagundi Group (Rhodesia) have yielded a δ 13 C mean of +8.2 ± 2.6% vs PDB.

TL;DR: In this article, the authors measured the solubility of silver chloride in sodium chloride solutions of 5×10−5 − 3.0 m over the temperature range from 100 to 353°C at the saturated vapour pressure of the system.

TL;DR: The Monte Carlo method of error propagation as mentioned in this paper consists of repeated calculation of a quantity, each time varying the input data randomly within their stated limits of precision, and the distribution of the calculated quantity then shows the effects of the imprecision of the data.

TL;DR: In this paper, the molarities of the salts required to precipitate the maximum amounts of Fe, Al and humates decrease in the order: NaCl, MgCl2, CaCl2.

TL;DR: In this paper, shallow subsurfaces of feldspar grains were analyzed for K, Al, and Si by X-ray photoelectron spectroscopy, and it was concluded that in the absence of a compact precipitate layer, dissolution of a feld spars in the temperature range corresponding to deep diagenesis is controlled by the processes at the feld sparsolution interface and a leached layer more than one feld unit cell thick does not form.

TL;DR: In this article, a U-Th-Pb systematics study of Allende inclusions showed that U, Th and Sr concentrations in Ca, Al (pyroxene)-rich chondrules and white and pinkish-white aggregate separates were five to ten times higher than those of the matrix.