U-Pb baddeleyite age for the Paleoproterozoic Lac Esprit dyke swarm, James Bay region, Quebec; Radiogenic age and isotopic studies: Report 14

Geological mapping east of James Bay has revealed abundant, newly recognized northto northwestand northeast-trending Proterozoic diabase dykes in a part of the eastern Superior Province where information was previously scant. A magmatic crystallization age of 2069 ± 1 Ma (U-Pb, baddeleyite) was reported for a representative of the northto northwest-trending Lac Esprit swarm, distinguishing it from similartrending but older Matachewan and Mistassini dykes of the region. The Lac Esprit dykes represent an extensive diabase swarm with a Paleoproterozoic age so far unrecognized elsewhere in the eastern Superior Province. The age, together with published preliminary paleomagnetic results, invites comparisons with a postulated, regionally extensive, radiating swarm north of Lake Superior (Fort Frances and reversely magnetized Marathon dykes), among others. The new dyke age contributes information to dyke swarm correlations in the Superior Craton and also aids in the assessment of models promoting apparent polar wander and continental drift of Laurentia during the Paleoproterozoic, or block rotation since this time. 2001-F5 M.A. Hamilton et al. 1 CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 1 Ministère des Ressources naturelles du Québec 82, boul. Québec Rouyn-Noranda, Quebec J9X 6R1 2 Department of Earth Sciences University of Waterloo Waterloo, Ontario N2L 3G1