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

Page 38 text:

Roy Shegelski Experience: Economic Geology Limnology - 1969-70 Canada Centre for Inland Waters GENERAL STRATIGRAPHY AND Fe Mn BEARING BEDS OF THE SEDIMENTS OF THUNDER BAY, LAKE SUPERIOR R. J. Shegelski In the summer of 1970, a reconnaissance survey was done of the bottom sediments of Thunder Bay. This was generally done with a Boston Whaler using a Phleger corer and a Ponar grab sampler and 147 sample points were done in this manner. Three sonar traverses were also made in the Bay. Samples were brought back to the laboratory for analysis. Cores were split and lithologies were recorded. Samples from cores were analysed by x-ray diffractometer, thin and polished sections were made of various parts and certain layers were analysed for iron and manganese. Results of analyses indicate that the sediments in Thunder Bay can be divided into five categories. (1) Varved Clay. (2) Weathered Varved Clay. (3) Intermediate Clay. (4) Upper Deltaic Sediment. (5) Upper Trough Sediment. Through correlation of the cores and sonar runs, the stratigraphy has been established as such. The Varved Clay is the oldest, the Weathered and Intermediate Clays are the second oldest and the Upper Sediments are the youngest and over- lies the previous types. An areal distribution is shown in the accompanying map. Results of the iron and manganese analyses indicate that the Upper Sediments contain anomalously high concentrations of iron and manganese. It has been proposed that upward migration of connate waters rich in iron and manganese has produced highly concentrated layers of iron and manganese near the top of the Upper Sediments. The proposed mechanisms of concentration are precipitation, burial subsequent resolution and upward migration causing redeposition at an appropriate Eh, (pH) interface. CONGRATULATIONS AND BEST WISHES to the Graduates M. W. Bartley Associates Ltd. Geologists 204 Toronto - Dominion Bank Bldg. Thunder Bay, Ontario 36

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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