| Summary: | Neoarchean volcanic rocks of the Beaulieu River volcanic belt (ca. 2.6 Ga) are found in the Sunset Lake area, located approximately 110 km east-northeast of Yellowknife, NT. Volcanic rocks within the Beaulieu River volcanic belt are dominantly composed of tholeiitic basalts, calc alkaline basaltic andesites, and minor amounts of calc-alkaline rhyolites. The Beaulieu River volcanic belt structurally overlies the ca. 2.9 Ga Sleepy Dragon complex and are conformably overlain by turbidites of the Burwash Formation. The aim of this study is to identify the relative age and stratigraphic relationship between the stratigraphy of the rhyolite dome in south Sunset Lake area and the felsic rocks that host the Sunrise volcanogenic massive sulfide (VMS) deposit 6 km to the north. The volcanic rocks of the southern portion of Sunset Lake area are more complex than originally mapped at a 1:50,000 scale by Lambert (1988). They are volumetrically dominated by lavas; however, the stratigraphy contains a significant (~ 15‒20 vol.%) amount of volcaniclastic rocks, which are interpreted to have been deposited by debris flows and eruption fed density currents in a submarine environment. This study shows that the volcanic succession consists of massive and pillow andesite to basalt, mafic tuff to tuff breccia, and lesser amounts of massive to in-situ brecciated, weakly quartz-feldspar phyric rhyolite, heterolithic felsic tuff to lapilli-tuff, and felsic tuff to tuff breccia. The lavas range from tholeiitic to calc-alkaline affinities and share similar trace element signatures to that of a typical modern arc. While the rhyolite dome in south Sunset Lake area does not show significant mineralization, there are similarities in lithologies, lithofacies, lithogeochemistry, and stratigraphy to that of the stratigraphy that hosts the Sunrise deposit. The study will provide a better understanding of the stratigraphy, volcanic and tectonic settings of the volcanic rocks in the Sunset Lake area, thereby also allowing for a better understanding ...
|
|---|