Geological setting of Paleozoic strata in the Mount Todd - Adams Lake region, south-central British Columbia

The (?)Paleozoic Sicamous and Tsalkom formations overlie deformed metasedimentary rocks of the Proterozoic and/or Paleozoic Silver Creek Formation in the Adams Lake area. The contact between these units may be transitional, an unconformity, or a fault. The Sicamous Formation can be correlated with unit EBL of the Eagle Bay Assemblage in the Adams Lake–Clearwater region. A sequence of carbonaceous phyllite and slate separates the Silver Creek Formation from the Upper Triassic Nicola Group in the Mount Tod area. These rocks may represent a previously unrecognized sequence, a Sicamous Formation equivalent, or metamorphosed sedimentary rocks at the base of the Nicola Group. 2001-A7 S.L. Acton et al. 1 CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 1 Contribution to the Ancient Pacific Margin NATMAP Project 2 9860 West Saanich Road, Sidney, British Columbia V8L 4B2 3 School of Earth and Ocean Sciences, University of Victoria, P.O. Box 3055, Station CSC, Victoria, British Columbia V8W 3P6 Calcareous rocks of the Sicamous Formation host the Steep skarn and Serpent massive sulphide deposits. The Silver Creek Formation exhibits sulphide mineralization adjacent to a quartz-vein stockwork system within the Chase Silica quarry. Previously unrecognized massive sulphide mineralization occurs within the Nicola Group. Résumé Les formations (?)paléozoïques de Sicamous et de Tsalkom surmontent des roches métasédimentaires déformées de la formation protérozoïque et/ou paléozoïque de Silver Creek dans la région d’Adams Lake. Le contact entre ces formations peut être une transition, une discordance ou une faille. La Formation de Sicamous peut être mise en corrélation avec l’unité EBL de l’Assemblage d’Eagle Bay dans la région du lac Adams et de Clearwater. Une succession de phyllade et d’ardoise carbonatés sépare la Formation de Silver Creek du Groupe de Nicola (Trias supérieur) dans la région du mont Tod. Ces roches pourraient représenter une séquence jusqu’à maintenant non reconnue, un équivalent de la Formation de Sicamous, ou une séquence de roches sédimentaires métamorphisées à la base du Groupe de Nicola. Les roches calcaires de la Formation de Sicamous encaissent le gisement skarnifère Steep et le gisement de sulfures massifs Serpent. La Formation de Silver Creek présente une minéralisation en sulfures près d’un réseau de filons de quartz anastomosés en stockwerk dans la carrière Chase Silica. Une zone minéralisée de sulfures auparavant non reconnue se rencontre dans le Groupe de Nicola. INTRODUCTION T thedistalmarginofancientNorthAmerica in south-central British Columbia is problematic. Within the Thompson–Okanagan–Shuswap region, strata included within the pericratonic Kootenay Terrane are poorly exposed, obscured by intense CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 2001-A7 S.L. Acton et al. 2 deformation, and mapped only at reconnaissance scale (Fig. 1; Wheeler and McFeely, 1991). For example, the relationship of pericratonic strata in the Mount Tod–Adams Lake area to rocks of the Eagle Bay Assemblage to the north and the Sicamous, Tsalkom and Silver Creek assemblages to the east and south is uncertain (Jones, 1959; Okulitch, 1979; Schiarizza and Preto, 1987). Rocks in the Mount Tod–Adams Lake region are host to several polymetallic massive sulphide deposits. However, the distribution, setting, and age of most of these deposits is not well established (Höy, 1999). Mapping of the area west of Adams Lake to Mount Tod was undertaken as part of the Ancient Pacific Margin NATMAP Project in an attempt to address these problems (Fig. 2 and 3). Particularly, detailed and reconnaissance field work focused on the following: 1) the relationship of rocks of the Lower Cambrian to Mississippian Eagle Bay Assemblage in the Adams Lake–Clearwater region and the Paleozoic Tsalkom and Sicamous formations mapped west and south of Adams Lake to rocks in the Mount Tod area; 2) the structural and tectonic relationships of pericratonic rocks in the Adams Lake–Mount Tod region; and 3) the distribution and setting of mineral deposits within the Mount Tod–Adams Lake region. This paper summarizes the initial findings of fieldwork completed during the summer 2000 season. STRATIGRAPHY Silver Creek Formation T Silver Creek Formation is a highly deformed and metamorphosed assemblage of pelitic schist, gneiss, amphibolite, siltstone, carbonaceous phyllite, aplite, and pegmatite. These rocks have been metamorphosed to sillimanite grade and deformed into a series of tight, polydeformed folds. The age of the Silver Creek Formation is unknown, but may be Upper Proterozoic, or as young as Middle to Upper Paleozoic (Okulitch, 1979, 1989; Thompson and Daughtry, 1997; R.I. Thompson, pers. comm., 2000). 2001-A7 S.L. Acton et al. 3 CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter