Late Paleozoic felsic volcanics in southern New Brunswick and related uranium mineralization

Abstract

Three units of Late Paleozoic felsic volcanics within southern New Brunswick were examined geochemically and petrographically to determine their genetic history and economic potential. The Late Devonian Harvey and Piskahegan Groups are predominantly composed of peraluminous volcanics, and were previously considered coeval since they contain similar stratigraphy, and formed during the same pulse of igneous activity. The younger, Viséan aged Cumberland Hill formation is characterized by peralkaline trachytes and rhyolites, forming through extensive fractional crystallization of alkali basaltic magma, likely derived from a mantle plume. The Harvey, and to a lesser extent, Piskahegan Group display excellent economic potential, enriched in uranium and rare earth elements. Cumberland Hill exhibited significantly lower concentrations of economic elements, slightly elevated in incompatible trace elements, including uranium. This study determined Harvey and Piskahegan are not genetically related, it also refined the genetic history and economic potential of southern New Brunswick.