The application of Quaternary geology and glacial sedimentology is given as a broad guide for geochemical exploration in glaciated terrain. Predictive models of glacial dispersal provide an important basis for tailoring drift prospecting methods to suit regional variations in ice flow history and dynamics. The models relate compositional variations in glacial dispersal trains to ice flow direction, glacial history and subglacial processes. They are continually refined with reference to the geological and physical properties of the ice bed; new empirical field evidence constraining particle trajectories; and knowledge of subglacial processes affecting glacial erosion, transport and deposition. Transport at the ice bed leads to an exponencial decrease in indicator concentrations with increasing distance of glacial transport, whereas linear decrease is associated with englacial transport, and may be characteristic of ice streams. The partitioning of rock and mineral fragments through subglacial comminution leads to compositional differences among size fractions that can reflect intensity of subglacial process, distance of transport, and provenance; hence, the choice of size fraction is important to drift prospecting by geochemical methods.
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Drift Exploration in Glaciated Terrain
This volume describes the use of till geochemical and indicator mineral methods for mineral exploration in glaciated terrain of Canada. The principles and examples described in this volume wil have direct applications for exploration companies and prospectors exploring for diamonds, precious and base metals and uranium in glaciated parts of North America, northern Europe and Asia and mountainous regions of South America.
The first two papers in this volume provide an introduction to glaciated terrain and the two styles of glaciation that have affected the world, continental glaciers in broad flat lying Shield areas and alpine glaciers in mountainous terrain. Sampling techniques are described next, followed by an introduction to the use of heavy minerals. Heavy mineral methodss have become an important exploration tool in glaciated terrain for gold and base metals and, in the last ten years, for diamonds. Lake sediments and biogeochemical methods are also included in this volume as a complement to geochemical and indicator mineral methods in glaciated terrain. A chapter on GIS has been included because data interpretation and display are important and essential parts of any regional or detailed geochemical survey. The remainder of the volume is case studies for the three main glaciated terrain tyes in Canada: Shield, Appalachia and Cordillera