Showing papers in "Chemical Geology in 1975"

TL;DR: In this article, a procedure for analysis and pretreatment of natural-water samples to determine very low concentrations of Al is described which distinguishes the rapidly reacting equilibrium species from the metastable or slowly reacting macro ions and colloidal suspended material.

TL;DR: The ternary relation between the elements Rb, Ba and Sr in granitoid rocks is discussed in this article, which proved to be useful in tracing differentiation trends in acidic suites.

TL;DR: In this article, the isotope-maturity relationship of natural gases is used to estimate displacement along fault systems or in determining the direction of gas migration, and it is shown that migration seems to cause no essential changes in the carbon-isotopic composition of the gas components.

TL;DR: In this paper, a mixed-solvent ion exchange technique for separating trace amounts of rare-earth elements from silicate rocks and minerals is described, with a two-column method, bulk separation of rare earths from other elements being accomplished on the first, and separation into three groups for mass-spectrometric analysis on the second.

TL;DR: The rare polycyclic aromatic hydrocarbon minerals curtisite, pendletonite and idrialite have been analyzed by chromatography, and ultraviolet and mass spectrometry as mentioned in this paper.

TL;DR: An electrochemical model for the weathering of massive sulphide deposits that have undergone conditions similar to those affecting the Kambalda nickel deposits is presented in this article, where the effect on the model of physical perturbations such as rising and falling water table, faulting, etc.

TL;DR: In this article, a new method for organic-carbon analysis in recent sediments is described, where the removal of carbonates is performed by phosphoric acid in aluminum cupels, which are folded after drying and put into the crucibles for dry combustion.

TL;DR: In this paper, the trace-element abundances are discussed in terms of the petrological problems, particularly the origin of calc-alkali magma, and the calcalkali rocks can be classified into three types which correspond to Kuno's three basalt-magma types.

TL;DR: An electrochemical study of nickel sulphide ore from three Kambalda shoots shows that the various parameters measured correlate both with depth and the degree of alteration of the ore as discussed by the authors, which supports the hypothesis that galvanic corrosion resulting from differential aeration is the major mechanism in weathering the ore.

TL;DR: The bioinorganic fraction of the dermal granules of Molpadia intermedia from a wide variety of habitats has been studied by chemical analysis, electron microscopy, X-ray diffraction, thermal analysis, visible and infrared spectroscopy and magnetic susceptibility as discussed by the authors.

TL;DR: Partition coefficients of uranium between phenocrysts and their host groundmass have been determined by fission track mapping as mentioned in this paper, showing that U is strongly partitioned into the liquid and only a small fraction of the total whole-rock U content is present in the major rock-forming minerals.

TL;DR: Samples of unaltered and metamorphosed Leadville Limestone (Mississippian, Colorado) were analyzed by neutron activation for ten rare-earth elements (REE) as mentioned in this paper.

TL;DR: The granitic and charnockitic intrusions in the Precambrian migmatites around Farsund in southern Norway have previously been shown to be successively intruded as well as being geochemically different.

TL;DR: In this paper, chemical analyses for Na, K, and trace elements of muscovite and potassium feldspar of granitic rocks are given for equilibrium and the distribution of trace elements in coexisting minerals suggests that equilibrium was attained and that muscoveite is a primary mineral.

TL;DR: In this paper, a radiochemical neutron activation analysis was performed on ten eclogites in gneiss and one peridotite in dunite-peridotites in the Nordfjord-Molde area, west Norway.

TL;DR: In this article, the authors determined 87 Sr 86 Sr ratios of the Tethys Sea by analyzing limestones of Permian to Late Cretaceous age from the overthrusted sequence of central and northern Euboea.

TL;DR: In this paper, the rare earth and other trace elements were analyzed by using spark-source mass spectrometry, showing that rare earth element chondrite normalised patterns showed enrichment of the lighter elements compared with the heavier elements.

TL;DR: Gold concentrations have been determined by neutron activation in sixteen samples of komatiites and related rocks from Barberton, South Africa as discussed by the authors, which give Au values in the ranges 1.5 ppb with no evidence for anomalously high values in such old primitive igneous types.

TL;DR: The major-, minor and trace-elements chemistry of Hercynian granitoids and their minerals from the central area of northern Portugal indicates that the composition of the rocks and also of their minerals varies in the comagmatic sequence of granite, aplite and pegmatite.

TL;DR: In this article, the 87 Sr 86 Sr ratios appear to increase in a general way with increasing depth to the Benioff zone and the strontium isotope ratios are higher than from most island arcs; this is believed to be due to contamination.

TL;DR: The petroporphyrins of a Cretaceous crude oil, La Paz, from western Venezuela are shown to be a mixture of etio and DPEP homologues (C 27 -C 39 ) maximising at C 30 and C 31, respectively as discussed by the authors.

TL;DR: The atomic absorption spectrometric determinations of iron, calcium, and magnesium in the fluoboric-boric acids matrix are seriously interfered by the presence of silicon and aluminum as mentioned in this paper.

TL;DR: The water-laid tuff beds in the mine sequence at Mount Isa, Queensland, yield anomalous whole-rock isochron results as discussed by the authors, which are interpreted in terms of continued mobility of minor elements in the water-rich sediments while deep-burial conditions persist.

TL;DR: In this paper, the six international geological reference materials of South African origin have been analyzed for their rare-earth content using the technique of ion exchange, combined with spark-source mass spectrography.

TL;DR: In this paper, the authors studied an Albian glauconite-phosphate-carbonate ore in the Sierra de Espuna (Murcia), situated in the betic Cordilleras, nappe of Malaga.

TL;DR: In this paper, the origin of saline waters in the Shiraz-Sarvistan area, Iran, is determined by a combined isotopic (18 O and D) and chemical characterization.

TL;DR: The radioelement concentrations and their distributions in the light (biotite hornblende) and dark (charnockitic) Farsundite suggests that they are distinct plutons and not comagmatic as discussed by the authors.

TL;DR: An alkane distribution in which isoprenoid alkanes are present in excess of n -paraffins and pristane, phytane, and norpristane are the major components, has been found in two different beds of the Irati oil shale, Brazilian Permian formation of Sao Mateus do Sul, Parana as discussed by the authors.

TL;DR: Santorini solfataric sulfur and sulfates of the Nea Kameni solfacia, Santorini, Aegean Sea, Greece, show a clear enrichment in the heavy sulfur isotope 34S against the assumed primordial 32 S 34 S ratio of 22,220.