CHARACTERIZATION OF A LATE PALEOZOIC ARC SECTION IN THE TERRACE-KITIMAT AREA, BRITISH COLUMBIA

The Mt. Attree volcanic complex is a Paleozoic arc section exposed in the Terrace-Kitimat region, British Columbia. The volcanics have been reported to contain potential volcanogenic hosted massive sulfide deposits. A structural, petrographic, geochemical and geochronologic study in volcanics and associated plutons was completed to characterize the volcanic facies, geochemistry, deformation, mineralization and geochronology of the section. Field observations and geochemistry show that Mt. Attree volcanic complex compositions range from basaltic through rhyollitic, with andesitic compositions dominating. Locally, volcaniclastic units are intercalated within the volcanics. Geochemical data is suggestive of an island arc affinity. The arc section can be divided into eastern and western exposures. Eastern exposures show more distal facies from south to north. Western exposures likely represent deeper structural levels due to the generally higher metamorphic grade and larger volume of intrusive material in the section. No previous volcanic ages existed for the arc section. Volcanics and cross-cutting plutons yield Mississippian to Pennsylvanian ages. Deformation recorded in Paleozoic volcanics and Paleozoic through Cenozoic plutonics (belonging to the Coast Plutonic Comlplex) is related to contraction along the western edge of Stikinia. Mineralization post-dates volcanism and is likely remobilization during Coast Plutonic Complex construction.