Lakehead University Geology - Journal Yearbook (Thunder Bay, Ontario Canada)

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Dr, R. H. Ridler, Ph.D. , University of Wisconsin Two years post-doctoral study, University of Western Ontario, Presently, Research Scientist, Geological Survey of Canada, Five summers with the Ontario Department of Mines, Research Archaean volcanic stratigraphy and mettallogeny, in particular exhalite and gold. Gold Metallogeny and the Geological Cycle in the Archaean Abstract Archaean geology is characterized by polycyclic assemblages of related plutonic, volcanic and sedimentary rocks representing the de-sialification of the proto-mantle. The ideal cycle comprises, from oldest to youngest, a mafic volcanic plate accompanied by mafic intrusives; a felsic volcanic pile accompanied by felsic intrusives; and annuli of volcanigenic sediments. Folding may precede or follow a cycle or, rarely, intervene between members of a cycle. Regional deformation and metamorphism conclude the Archaean; stabilization, uplift and brittle failure follow. Intrusive, volcanic and sedimentary phases of a cycle have accompanying syngenetic gold minerali- zation. Both clastic and chemical sedimentary deposits are known. Volcanigenic chemical sediments (exhalites) are particularly favourable. Exhalites have traditionally been classified into oxide, carbonate, sulfide and silicate facies to which arsenide, sulfate, and halide should be added. A further subdivision into sub facies based on cation population is proposed, e.g. (Fe Cu Zn Ag Pb (Au?) ) sulfide. Sampling of diverse species of exhalite at the south margin of the Abitibi Basin indicates a close affinity of gold and sulfur. Ductile and brittle deformation and metamorphism have recrystallized and remobilized the gold anomalies to varying degrees. Complex gold-quartz vein histories are a common result but migration of gold is restricted to a few tens of feet or less. CLIFFS OF CANADA LIMITED Active in Exploration and Mine Management in Canada Property Submissions Invited 204 Toronto - Dominion Bank Bldg. Thunder Bay , Ontario 54

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ei 4 Dr E. H. Chown Do vole University, Montreal Topic: The Geology of the Otish Mountains, Central Quebec . Dr J. Tuzo Wilson Principal of Erindale College and Pro- fessor of Geophysics at the University of Toronto Topic: Continental Drift and Plate Tectonics Dr E. Irving Earth Physics Branch Department of Energy, Mines and Resources Topic: The Origin of Marine Magnetic Anomalies . Dr M. M. Kehlenbeck Queen ' s University As of July 1st, 1971, Assistant Pro- fessor of Geology, Lakehead University Topic: Deformation and Recrystalli- zation Textures in the Pipmuacan Anorthosite, Quebec . Patrick W. G. Brock Visiting Professor, Queen ' s College of City University of New York Topic: Precambrian Shield in East Africa: structural age relationships of intrusive and metesomatic alkaline rocks. Geomorphological studies of Fast African Rift Valleys . 53

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O ' We are interested in receiving submissions on properties of merit for examination and possible option in Canada or elsewhere SUITE 1309-7 KING STREET EAST TORONTO I, CANADA LIMITED 55