Showing papers in "Chemical Geology in 1970"

TL;DR: In this article, the rates of hydration of forsterite to serpentine and brucite and of enstatite to talc were investigated and it was suggested that the natural processes are diffusion controlled.

TL;DR: In this paper, a model incorporating both biological and environmental factors has been developed to account for isotope ratio variations in coelenterate carbonate, and a depth effect predicted by the model provides an opportunity to test its validity in that a number of critical relationships must be observed.

TL;DR: A variety of chemical and/or physical procedures have been used in the past to isolate or concentrate the "insoluble" organic matter (commonly called kerogen) present in a sedimentary rock.

TL;DR: The results from the electron paramagnetic resonance (E.P.R.) spectra of Maganese in fourteen natural and synthetic carbonate minerals show that manganese exists as Mn 2+ in highly ionic lattice sites which are isolated in the carbonate mineral and slightly distorted from octahedral symmetry as discussed by the authors.

TL;DR: The three principal exsolution mechanisms are continuous, discontinuous (cellular), and spinodal decomposition as mentioned in this paper, which are both initiated by a classical nucleation event, but the latter involves the formation of a duplex cell.

TL;DR: In this paper, the site preferences of individual transition metal ions in the olivine, orthopyroxene and clinopyroxenes structures have been predicted from the mean metal-oxygen distances, site distortion, cation size and crystal field criteria.

TL;DR: In this article, the concentration of thallium in the water column at a station in the North Atlantic has been investigated using a neutron activation procedure, and values ranging from 9.4-16.6 ng/l were found.

TL;DR: In this paper, it was shown that an exact solution exists for the isotopic analysis of lead using a double spike, and that the iterative procedure given by Compston and Oversby (1969) is therefore unnecessary.

TL;DR: In this article, the reaction of gaseous carbon dioxide with a solution of barium hydroxide is used as a basis of an accurate, rapid and inexpensive volumetric method for the determination of carbonate and organic carbon.

TL;DR: The water content of sinters deposited from the same thermal water can be expressed in terms of their SiO2 and Me2O3 (Me = Al and Fe) contents: (H 2 O )=0.13(SiO 2 ) + 7.6( Me 2 O 3 ).

TL;DR: In this article, the chemistry of manganese in natural waters was investigated and it was found that the precipitation of iron was complete within 48 hours from the time of collection of the water sample, generally only a small fraction of the total manganized had precipitated in about a week's time.

TL;DR: Using the areas under Mossbauer peaks, the amount of Fe 2+ in structurally different cation positions, and the Fe 2+, Fe 3+ ratio can be calculated in silicate minerals as mentioned in this paper.

TL;DR: In this paper, the existence of porphyrins of higher aromaticity in petroleum asphaltenes has been explored and their properties were studied by a number of spectral methods such as UV-visible, infrared, NMR, mass and ESR.

TL;DR: For the ternary systems FeS2, FeS 2, FeS 3, FeAs 2, and FeAs 3, the limits of the solid-solution fields of the higher sulphides, arsenides, tellurides and selenides of the transition metals are governed by the Ligand-field theory as mentioned in this paper.

TL;DR: The trend of K Rb ratio with K content is similar to that shown by oceanic tholeiites as mentioned in this paper, which may not indicate a mantle origin but may only reflect partitioning of K and Rb between liquid and plagioclase.

TL;DR: The reference carbonate rocks GFS 401, GFS 402, NBS 1a, nBS 1b, and NBS 1014 (all limestones), together with GFS 400 and GFS 403 (all dolostones), have been analyzed by emission spectrometric methods as discussed by the authors.

TL;DR: In this article, a determination of the carbon and oxygen isotopic composition in the carbonates of ejected limestone blocks and related fluorine and boron bearing geodes found in the Corcolle “black pozzolans” from the Alban Hills was made.

TL;DR: Uranium and thorium contents have been determined for fifteen silicate lavas, two carbonate lavas and the plutonic blocks from Oldoinyo Lengai, Tanzania.

TL;DR: In this paper, the authors used an electron microprobe for the study of local cathodoluminescence in calcite and found that the electronic states involved in cathodluminescent calcite are interpreted on the basis of ligand field theory, the 4A1g,4Eg(G)→6A 1g transition in Mn2+ activator is found to be responsible for the sharp luminescent peak at 5,800 A.

TL;DR: In this article, a simplified mathematical theory for the double-spike method of correcting for fractionation in lead isotopic analysis is presented, and expressions for the true isotopic ratios of a sample in terms of the measured isotopic ratio of the spiked and unspiked sample, and the known isotopic relations of the spike are given.

TL;DR: A basalt boulder, buried at a depth of 20 cm in a fossil latosol of the Negev, southern Israel, has altered forming differently coloured concentric diffusion rings.

TL;DR: In this article, a method is described which allows the determination of germanium (down to ⋍ 0.05 μ g ) in iron meteorites or other alloys using neutron activation analysis.

TL;DR: In this article, the emission spectrometric results of the trace elements Ag, B, Ba, Bi, Cd, Co, Cr, Cu, Ga, Li, Mo, Ni, Pb, Rb, Sn, Sr, V, Y, Zn and Zr have been tabulated.

TL;DR: In this paper, the distribution of divalent metals, Ni, Co, Fe, Zn, and Mn, between coexisting minerals is surveyed in terms of the exchange equilibria with Mg.

TL;DR: In this article, the lead concentration, its isotopic composition, and the uranium content of Pennsylvanian anthracites have been determined, and it is interpreted that common lead was incorporated into the ancient bedded plant material in Carboniferous times prior to coalification, while the uranium was introduced into the anthracite after coalification.

TL;DR: In this paper, Thorium, uranium, and potassium concentrations have been measured by gamma-ray spectrometry in graywacke sequences from the Wind River Mountains of Wyoming and the Knife Lake area of Minnesota.

TL;DR: Analyses of harzburgites from southwest Turkey are presented in this paper, where the chemistry remains constant throughout the range of serpentinisation except for losses in respect of some minor constituents, notably Al2O3 and CaO, in fully serpentinised rocks.