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

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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

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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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Report on First Year Field Trips by Eric Brown and Dave Powers Under the supervision of Dr. Mercy, Dr. Mothersill and Dr. Franklin, we first year Geology students proceeded on two field excursions. The first involved a three-fold purpose: one, to acquaint us with the unconformable nature of the Sibley Archean contact, and the paraconformable nature of the Sibley-Rove contact; two, to observe bedding, ripple marks, a sedimentary sequence of chert, mudstone, sandstone and conglomerate; three, to view some diabase sheets which cut across the bedding. On the second field trip we proceeded to Pardee Township and Pigeon River to observe cuestas, dykes and concretions in the Rove shale. This trip also took us to the explor- atory site of Great Lakes Nickel Company. Our first stop on the Sibley group field trip was at the site of the Wolf River. Here the pro- fessors pointed out to us the sequence of varved clays in the sedimentary bedding through which the Wolf River has cut. The next stop, at a gravel pit near Kama Bay hill, served somewhat the same purpose - to illustrate the bedding and distribution of grain sizes. At Kama Hill a number of geomorphological features were pointed out to us. They included the following: a large anticlinal fold; interbedded mudstone and sandstone; small lenticular or discontinuous diabase sills; a chert horizon, with fine lamination of interbedded carbonate and anthraxolite ; massive mudstone; purple shale; and a thick diabase cap rock. After these observations we moved on to scrutinize a deposit of red sedimentary rocks that had been intruded by a diabase sill. This sill had penetrated down through the sedimentary rocks into the Archean basement. We made our next stop in the region around Red Rock, and saw several outcrops of Sibley rocks, followed by a region of granite outcrops. The next point of interest was a quarry composed of black Rove shale overlying a Gunflint formation. Embedded within the Rove shale were large, irregular carbonate concretions, possibly of organic origin. The final stop of this trip brought us to an exposed basal unit of the Sibley group which is comprised of polymictic conglomerates. Here also was exhibited a well-defined contact zone between the conglomerate and sandstone. On the second field trip we headed south to the United States border. A range of eroded mountains known as the Norwesters , which includes Mount MacKay, follows the east side of the highway. The cuestas are composed of black shale (Rove formation) with a diabase cap. As we proceeded southward, the topography changed to one of more rugged relief which is related to the bedrock geological changes. The Great Lakes Nickel Company exploration project was the first stop on this trip. Our group climbed up to the adit, which was constructed by the company into the sulphide zone, to investigate the rocks in and near the adit. After stripping the adit of most of the available chalcopyrite outcrops, we returned to the bus. On our next stop at the Middle Falls Campground on the Pigeon River, we were mainly concerned with the diabase dyke which cut across the region and gave rise to the falls. The dyke crossed the highway to where it cut into a Rove shale formation; the contact zone between the dyke and the shale was closely observed. Also, the same carbonate mineral concretions evident at the Rove shale quarry mentioned before were evident here. Our last stop was at the end of Memory Lookout Road. At the lookout it was pointed out that we were standing on a dyke which could be visually followed (intermittently) to the south, as it stands up above the surrounding country rock in that area. Two other dykes could also be observed which ran parallel to the dyke on which we were standing. The significance of these field trips was not fully realized until such time in the academic year when some of the processes involved in the formation of these geomorphological features were comprehended. 56