Volcanic stratigraphy and mineral potential of the Aylmer dome, southeastern Slave Province, Northwest Territories

The Aylmer dome is a prominent geological feature in the northeastern Walmsley Lake map sheet (NTS 75 N), southeastern Slave Province. The dome is composed of a granitoid core rimmed by a narrow volcanic belt, overlain by regionally extensive metaturbidite of the Yellowknife Supergroup. The volcanic stratigraphy comprises a conformable succession of basal mafic flows and gabbroic sills, overlain by a fine-grained, intermediate to felsic volcaniclastic sequence with a lens of intermediate breccia in the northwest. The upper felsic sequence is capped by iron-formation deposited at the volcanic–sedimentary interface. 2001-C5 J. Renaud et al. 1 CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 1 A contribution to the Walmsley Lake TGI Project (#000013) 2 University of Western Ontario, Department of Earth Sciences, Biological and Geological Building, London, Ontario N6A 5B7 3 Department of Indian and Northern Affairs, Northwest Territories Geology, Box 1500, Yellowknife, Northwest Territories X1A 2R3 Airborne magnetic and electromagnetic geophysical surveys defined several conductive and magnetic horizons within the volcanic belt, and a continuous magnetic and conductive response coincident with the capping iron-formation. Ongoing work is aimed at resolution of a more detailed stratigraphy and petrogenesis of the volcanic rocks and will aid in assessing the mineral potential of the belt, in particular the magnetic and conductive horizons identified by geophysics. CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 2001-C5 J. Renaud et al. 2 Résumé Le dôme d’Aylmer est une structure géologique saillante sur la coupure de la partie nord-est du lac Walmsley (SNRC 75 N), dans le sud-est de la Province des Esclaves. Il est formé d’un noyau granitoïde bordé d’une ceinture volcanique étroite, que recouvre une métaturbidite du Supergroupe de Yellowknife très étendue à l’échelle régionale. La stratigraphie volcanique comprend une succession concordante de coulées mafiques de base et de filons-couches gabbroïques que recouvre une séquence volcanoclastique à grain fin de composition intermédiaire à felsique accompagnée d’une lentille de brèche intermédiaire dans le nord-ouest. La partie supérieure de la séquence felsique est coiffée d’une formation de fer déposée à l’interface volcano-sédimentaire. Les levés géophysiques magnétiques et électromagnétiques aériens ont permis de définir plusieurs horizons conducteurs et magnétiques dans la ceinture volcanique et une réponse magnétique et conductrice continue qui coïncide avec la formation de fer de recouvrement. Les travaux en cours visent à obtenir des données stratigraphiques et pétrogenétiques plus détaillées sur les roches volcaniques et permettra d’évaluer le potentiel minéral de la ceinture, en particulier celui des horizons magnétiques et conducteurs mis en évidence par les levés géophysiques. INTRODUCTION AND PREVIOUS WORK T study is part of a multidisciplinary geological project that commenced in 2000 in the Walmsley Lake area, southeastern Slave Province (see MacLachlan et al., in press). The Walmsley Lake Project is jointly funded and undertaken by the C.S. Lord Northern Geoscience Centre in Yellowknife and the Geological Survey of Canada, under the Targeted Geoscience Initiative. The specific work reported here on the Aylmer dome represents the field component of an M.Sc. thesis project at the University of Western Ontario and is supported by the C.S. Lord Northern Geoscience Centre and Navigator Exploration Corporation. The Aylmer dome is situated in the northeastern corner of the Walmsley Lake map area, 350 km northeast of Yellowknife (Fig. 1). It occurs about 80 km north of the treeline within low-lying barrenlands characterized by glacial outwash, muskeg, and numerous lakes. Outcrop is sparse especially on the eastern and southern margins of the dome. The results reported here are based on three weeks of field mapping at 1:30 000 scale to better resolve the volcanic stratigraphy and document contact relationships between the volcanic belt and adjacent granitoid and metasedimentary rocks. Samples were collected for analysis to determine the geochemical characteristics of the rocks and their possible tectonic setting. Better resolution of the volcanic stratigraphy utilizing available high-resolution geophysical data will allow more critical assessment of the economic potential of the volcanic belt for hosting volcanic massive-sulphide and/or lode-gold mineralization. Particular attention will be paid to the volcanic-sedimentary interface, which is interpreted here (see below) as an Algoma-type iron-formation, and may have potential to host lode gold. 2001-C5 J. Renaud et al. 3 CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter