GEOCHEMICAL CHARACTERIZATION AND GEOCHRONOLOGY OF THE PALEOZOIC MOUNT ATTREE VOLCANIC COMPLEX, TERRACE, BRITISH COLUMBIA

The Paleozoic Mt. Attree volcanic complex, exposed in the Terrace, British Columbia area, has economic potential in the form of volcanogenic hosted massive sulfide (VHMS) mineralization. Recent regional mapping in the Terrace has created a foundation for this work which provides a geochemical and geochronologic framework for the region and further assessment of economic mineralization in the Mt. Attree volcanic complex. Geochemical, assay and geochronologic samples were collected from six target areas within the volcanic complex, associated intrusions and cross-cutting dikes (interpreted to be potential feeders for the volcanics). Field, petrographic and geochemical analyses show that volcanic units range in composition from basaltic to rhyolitic, with andesitic compositions dominating. Trace element geochemical patterns suggest that the volcanic complex was formed in continental margin or island arc setting. Geochemical analysis of known Paleozoic and undated intrusions and potential feeder dikes further suggest a subduction related continental margin or island arc system. Plutonic, volcanic and dike compositions generally overlap and exhibit little distinction, indicating a similar genetic origin. New geochronologic results from volcanic and intrusive units yield Mississippian and Pennsylvanian ages, ranging from 355-318 Ma. Younger intrusions document ages of deformation (likely episodic) within the Mt. Attree volcanic complex from Mississippian through Eocene time. Assays completed from targeted areas, in particular near the Gazelle Showing, exhibit elevated concentrations of Au and Ag with fewer sites exhibiting elevated Cu and Zn. The Mount Attree volcanic complex has lithologic, geochemical and geochronologic similarities to other Paleozoic VHMS deposits found in British Columbia and remains a source of potential economic interest.