Paleozoic volcanic assemblages and volcanogenic massive sulfide deposits near Tulsequah, British Columbia

Abstract

New fossil, structural, and lithological evidence shows that the dominantly andesitic terrane near the junction of the Taku and Tulsequah rivers, northwestern British Columbia, is a proximal facies, roughly age equivalent to late Paleozoic tuffaceous and argillaceous sedimentary rocks exposed near Tatsamenie Lake, rather than of Late Triassic age as previously mapped. Fusulinids from the Tulsequah sequence are Middle Pennsylvanian, whereas the limestones at the top of the Paleozoic section near Tatsamenie Lake are of Permian age. The Tulsequah sequence hosts the Tulsequah Chief, Big Bull, and Ericksen – Ashby massive sulfide deposits, which arc associated with small bodies of rhyolite.