LATE ARCHEAN REGIONAL DEFORMATION AND STRUCTURAL CONTROLS ON GOLD-QUARTZ VEIN MINERALIZATION IN THE NORTHWESTERN SLAVE-PROVINCE, NWT, CANADA

Late Archean crustal accretion in the northwestern Slave Province is s uggested to have involved approximately west-northwest-east-southeast directed horizontal compression that produced three episodes of deform ation recognizable in the northwestern Anialik River igneous complex ( ARIC) and Anialik River greenstone belt (ARGB). Observations show that the ARIC was probably emplaced as a series of synvolcanic sills prior to the earliest deformational event. Regional shortening produced a p ervasive foliation, downdip lineations and folding in the ARGB, and an early, subsequently folded, foliation in the northwestern ARIC. Postf old ductile and brittle-ductile deformation produced regional- and out crop-scale shear zones including the Sheeted Zone, which defines the-A RIC-ARGB contact. Younger rocks of the northwestern ARGB appear to hav e been tectonically juxtaposed along the Sheeted Zone against the olde r rocks of the northwestern ARIC. Greater brittle response, enhanced p ermeability, and cyclical increases in fluid pressure led to the devel opment and concentration of an anastamosing network of gold-quartz vei n bearing shear zones in the ARIC. Steep to subvertical shear-related linear fabrics show that regional-scale and mineralized shear zones ha ve a large component of vertical shear with predominantly east-side-up movement. The age relationships, proximity, and similarity of deforma tional structures in the Kangguyak gneiss belt, containing a craton-sc ale ductile deformation zone, and shear zones within the Arcadia Bay a rea, suggest contemporaneous development and regional late Archean str uctural relationships similar to those of shear zone hosted gold-quart z vein mineralization seen in the Abitibi Subprovince (Canada) and Yil garn Craton (Australia).