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Data of rock analyses; Progress report (1957)
Report of meeting H. U.S.A.
Some applications of thermodynamics to problems in economic geology. Department
of Geology,
Princeton
University,
Princeton,
New Jersey,
D.
HOLLAND,
The stability fields of the oxides and sulphides of fifteen metals have been plotted in threedimensional diagrams in which the logarithms of the oxygen fugacity and of the sulphur fugacity comprise the two horizontals axes, and in which temperature is plotted along the vertical axis. It is shown that on the basis of this type of diagram, mineral assemblages are predicted which are consistent with observations on metallic ore deposits. Many of the commonly observed mineral assemblages are found to lie along a “main line of descent” in this type of diagram. The observed descent can be understood in terms of classical ideas on the origin of hydrothermal ore deposits, and is used to derive fugacity data for a number of important volatile constituents in ore-forming fluids. The relationship between the calculated fugacities and the pressure of the volatile components of ore-forming fluids is outlined.
Data of rock analyses; Progress report (1957). MARJORIE Washington
HOOKER, U.S.
Geological
Survey,
25, D.C., U.S.A.
In 1952, the U.S. Geological Survey undertook the compilation of chemical analyses of igneous and metamorphic rocks from the world literature for the years 1914-1953. The first progress report, outlining the scope and procedures of the work, was given at the meeting of the Commission on Geochemistry (IUPAC) in Zurich in August 1953. The second progress report was presented at the 20th International Geological Congress in Mexico City in September 1956, and will be published in the Proceedings of the meetings. The systematic examination of the literature, based on a comprehensive list of more than 1600 periodicals and serials and several hundred books, is being conducted on a regional plan. Completed at this time are the publications of Africa, New Zealand, and Australia. Annotated and indexed references from the African and New Zealand publications have been published In process is the examination of the literature of the in Geochirnica et Cosmochimica Acta. United States, Great Britain, and Germany, a considerable part of which has been completed. Publication of any part of the analyses will not be attempted before examination of the literature is completed; the bibliographic data are being published as sections are completed in order to make the source material more readily available. Compilation of the analyses from the literature is proceeding simultaneously, although it does not necessarily keep pace with the examination of the literature. At this time, approximately 2500 analyses have been placed in the files and can be consulted in several ways. Geochemi&ry of some Swiss granites. TH. HOGI, Mineralogisches Institut, Universitat Bern, Bern, Schweiz, and D. J. SWAINE, The Macaulay Institute for Soil Research, Craigiebuckler, Aberdeen, Scotland. An investigation, based on petrological field observations and laboratory work, has been carried out on granites belonging to the Hercynian Aar Massif in the Swiss Alps. Granitic rocks make up 51 per cent of the surface of this autochthonous massif. Some of these granites are believed to be of early Hercynian age, and others were formed during the late Carboniferous or early Permian. These older granites show contamination by gneissic material from surrounding rocks. Such pre-Hercynian gneisses were formed from the oldest sediments of the Aar Massif. Field observations, petrological evidence, and trace-element data prove strong contamination of the so-called Lauterbrunner granite and the Innertkirchner granite. The contamination increa,ses towards the east of the massif, and the gneisses and contaminated granites have higher contents of some metals (for example Cr and V). Younger granites, for example the Central Aare granite and the Mittagfluh granite, are lower in Fe, Mg, and Ca but slightly higher in Si and K than the older granites and do not show any contamination. Average values for the trace-element contents of the Aar Massif granites are compared with published values for other granites. The trace-element data are discussed, and histograms are shown for several elements (number of samples plotted against contents). Reference is made to the concentration of some trace elements in rare minerals occurring in cavities.
159
Some applications of thermodynamics to problems in economic geology. Department
of Geology,
Princeton
University,
Princeton,
New Jersey,
D.
HOLLAND,
The stability fields of the oxides and sulphides of fifteen metals have been plotted in threedimensional diagrams in which the logarithms of the oxygen fugacity and of the sulphur fugacity comprise the two horizontals axes, and in which temperature is plotted along the vertical axis. It is shown that on the basis of this type of diagram, mineral assemblages are predicted which are consistent with observations on metallic ore deposits. Many of the commonly observed mineral assemblages are found to lie along a “main line of descent” in this type of diagram. The observed descent can be understood in terms of classical ideas on the origin of hydrothermal ore deposits, and is used to derive fugacity data for a number of important volatile constituents in ore-forming fluids. The relationship between the calculated fugacities and the pressure of the volatile components of ore-forming fluids is outlined.
Data of rock analyses; Progress report (1957). MARJORIE Washington
HOOKER, U.S.
Geological
Survey,
25, D.C., U.S.A.
In 1952, the U.S. Geological Survey undertook the compilation of chemical analyses of igneous and metamorphic rocks from the world literature for the years 1914-1953. The first progress report, outlining the scope and procedures of the work, was given at the meeting of the Commission on Geochemistry (IUPAC) in Zurich in August 1953. The second progress report was presented at the 20th International Geological Congress in Mexico City in September 1956, and will be published in the Proceedings of the meetings. The systematic examination of the literature, based on a comprehensive list of more than 1600 periodicals and serials and several hundred books, is being conducted on a regional plan. Completed at this time are the publications of Africa, New Zealand, and Australia. Annotated and indexed references from the African and New Zealand publications have been published In process is the examination of the literature of the in Geochirnica et Cosmochimica Acta. United States, Great Britain, and Germany, a considerable part of which has been completed. Publication of any part of the analyses will not be attempted before examination of the literature is completed; the bibliographic data are being published as sections are completed in order to make the source material more readily available. Compilation of the analyses from the literature is proceeding simultaneously, although it does not necessarily keep pace with the examination of the literature. At this time, approximately 2500 analyses have been placed in the files and can be consulted in several ways. Geochemi&ry of some Swiss granites. TH. HOGI, Mineralogisches Institut, Universitat Bern, Bern, Schweiz, and D. J. SWAINE, The Macaulay Institute for Soil Research, Craigiebuckler, Aberdeen, Scotland. An investigation, based on petrological field observations and laboratory work, has been carried out on granites belonging to the Hercynian Aar Massif in the Swiss Alps. Granitic rocks make up 51 per cent of the surface of this autochthonous massif. Some of these granites are believed to be of early Hercynian age, and others were formed during the late Carboniferous or early Permian. These older granites show contamination by gneissic material from surrounding rocks. Such pre-Hercynian gneisses were formed from the oldest sediments of the Aar Massif. Field observations, petrological evidence, and trace-element data prove strong contamination of the so-called Lauterbrunner granite and the Innertkirchner granite. The contamination increa,ses towards the east of the massif, and the gneisses and contaminated granites have higher contents of some metals (for example Cr and V). Younger granites, for example the Central Aare granite and the Mittagfluh granite, are lower in Fe, Mg, and Ca but slightly higher in Si and K than the older granites and do not show any contamination. Average values for the trace-element contents of the Aar Massif granites are compared with published values for other granites. The trace-element data are discussed, and histograms are shown for several elements (number of samples plotted against contents). Reference is made to the concentration of some trace elements in rare minerals occurring in cavities.
159