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

Page 41 text:

THE STRUCTURE, STRATIGRAPHY AND PETROLOGY OF THE NORTH END OF THE ABITIBI BLOCK 7, STURGEON LAKE, ONTARIO Lou Covello The Sturgeon Lake greenstone belt is typical of the rhyolite-andesite-basalt assemblage of Archean metavolcanic rocks in the Canadian Shield. It consists of thick volcano-sedimentary pile, broadly symformal in morphology with a central outcropping of infolded coarse, poorly sorted metasediments flanked to the north and south by the main metavolcanic sequence. The entire greenstone belt is engulfed in a gneissic basement complex and intruded by numerous late Archean granitic plutons. The north end of Abitibi Block 7 comprises a sequence of felsic and intermediate metavolcanics lying on the south side of the greenstone belt. Detailed mapping of this area has revealed the lithology to have a uniform east-west strike and near vertical dip. Individual rock units are essentially lens-like and relatively undeformed. Metamorphism is of greenschist facies, the common mineral assemblage being quartz, albite, carbonate ± chlorite, ± epidote, ± muscovite, ± chloritoid. Rhyolitic and rhyo-dacitic rocks tend to be pyroclastic in origin, while more mafic members often occur as pillow lavas, or vesicular and massive flows with minor pyroclastic and ash-flow type interbeds. PAST EXPERIENCE: 2 summers with Ontario Department of Mines in Timmins and Sault Ste. Marie, Ontario. 2 summers with Anaconda out of the Lakehead. 1 winter with Planet Mining of Sydney, Australia in North Queensland and Victoria. 1 summer with Noranda Exploration in Northwestern Quebec. 1 year with Mattagami Lake Mines, Sturgeon Lake, Ontario. 39

Page 40 text:

Copper and Molybdenum Distribution in the Soils of the Gavin Lake Copper-Molybdenum Property, British Columbia By Peter J. Vanstone The Gavin Lake property is located in south central British Columbia, about 25 miles east of McLeese Lake. The property lies on the eastern side of the Quesnel Trough, which is a trough of Mesozoic strata flanked by older Paleozoic and Proterozoic strata. Geologically, the property consists of two main rock groups: volcanic rocks, which include sediments of volcanic derivation, and porphyritic quartz monzonite. The volcanic sediments cover most of the property, with the volcanic flows occurring as a strip across one end of the property. Intruding into all these rocks is a dyke swarm of quartz monzonite porphyry. During the last field season a detailed geochemical survey was carried out on the property. The results of these samples were treated statistically to distinguish between the background samples and the anomalous samples. The anomalous copper and molybdenum areas were then outlined. These areas were of three types: high Mo-high Cu, high Mo-low Cu and high Cu-low Mo. Later in the summer a number of soil profiles were taken across one of each type of anomalous area. Using atomic absorption, these samples were analyzed for total Cu and total Mo. A number of the samples were also selected for partial analysis using S.D.T.A., as an aid in distinguishing between significant and non-significant anomalous areas. The copper and molybdenum values for the entire property were treated statistically to determine what effect topography had on their distribution. The results of treatment showed lower mean and standard deviation values for the hilltops than for the valley bottoms. The values for the valley slopes were intermediate between the hilltops and the valley bottoms. Taking into account the pH of the soil, the soil type, the underlying rock type, the topographic location ' and the copper and molybdenum distribution revealed by the soil profiles, a criterion was formed to distinguish between significant and non-significant anomalous areas. 38

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GENERAL STRATIGRAPHY AND TRACE ELEMENT DISTRIBUTION OF THE SEDIMENTS OF BLACK BAY, LAKE SUPERIOR R. D. Middaugh During the late summer of 1970 a reconnaisance survey of the bottom sediments of Black Bay was carried out. The sampling was done from a Boston Whaler using a Phleger gravity corer and a Ponar grab sampler. Unfortunately, due to weather conditions only 32 stations were completed. Samples, on being brought to the laboratory underwent various analysis. Grain size analysis were done using sieve and pipette methods. The Ph and Eh were recorded at the top and at various depths along the length of the core. The cores were split and logged and samples were taken at various intervals of x-ray diffractometer analysis and for trace element analysis using the Atomic Absorption unit. The trace elements analysed for were Cu, Fe, Mn, Cr, and Ni. Results of the x-ray diffractometer analysis indicate that there are three units present. 1) Glacially derived clay, 2) post glacial intermediate clay, 3) upper recent sediments. These units are conformable in the deeper parts of the bay but exhibit erosional contacts near the more shallow margins. The geochemical data indicate that the trace element concentrations are independ- ent of grain size. The data would also seem to indicate that the trace element concentrations are fairly uniform and show no anomalous values either vertically or horizontally relative to the lithology of the sediments of Black Bay. EXPERIENCE : Summer 1968 - General mapping and core logging in the Papaskwasati Basin and the Otish Mountains in North Central Quebec. Spring 1969, 70, 71 - Limnological studies of Lake Superior under J. S. Mothersill and Canada Centre for Inland Waters. 40