Analysis of Tyrrell Sea Deposits from the Vicinity  of the Victor Diamond Mine: Comparison of Four North American Clay Deposits

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Holloway, Jean
Victor Mine , Marine Sediments , Geotechnical Properties , Tyrrell Sea
The De Beers Victor Mine is an open pit diamond mine, located in the James Bay lowlands of northeastern Ontario. The lowlands are characterized by extensive peatlands overlying Tyrrell Sea sediments. One of the potential impacts of open pit mining, and the focus of the current research, is the potential for differential subsidence in the Tyrrell Sea sediments owing to continuous groundwater withdrawal from the underlying limestone aquifers. To fully understand the potential effects of subsidence, a better understanding of the nature and properties of the Tyrrell Sea sediments is needed. Subsidence is related to characteristics of the deposit, which will be determined by calculating four geotechnical properties. These properties of samples collected from the sediments of the Victor Diamond Mine were compared to the values from samples of Lake Agassiz sediments, Champlain Sea sediments, and the Bearpaw Shale. The properties of hydraulic conductivity, grain size, plastic and liquid limit, and mineralogy were determined for each sample and the results were analyzed and compared to data collected from the literature. The results indicate that the Tyrrell Sea sediments are a low plasticity clay, with a low liquid limit, a hydraulic conductivity higher than all the other clay deposits, is characterized as a clayey silt in terms of grain size, and has a mineralogy primarily containing quartz, illite, chlinochlore, and calcite. The mineralogy shows that the Tyrrell Sea sediment does not contain smectite minerals, which indicates that there is no relationship between Lake Agassiz and this deposit.
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