Late Precambrian Epeirogenic Uplift and Erosion of Southern Canadian Shield

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The Canadian Shield is an extensive bedrock plain of low relief that covers the northern United States and most of Canada. The exposed rocks are among the oldest on earth and were formed generally at elevated temperatures and pressures. The topo- graphic shield was formed by a broad uplift of the North American continent between about 1.6 and 0.5 billion years ago. The cause and timing of uplift is unknown: the only direct evidence for uplift is the presence of a 1 billion year erosional hiatus. The objective of this project is to reconstruct the uplift history of the shield during this erosional hiatus by measuring the apatite fission track cooling histories of surface samples collected from the shield in Ontario and adjacent areas. Results are expected to constrain the timing and rate of uplift which are important clues to the causes of the widespread uplift.