A field, geochemical and geochronological perspective on the origin of granitoids and mafic volcanic rocks in the Wecho River area and the nature of ancient crust in the southwestern Slave Province, NWT

The Wecho River area, located in the southwestern Slave Province, approximately 100 kilometres north of Yellowknife, NT, is dominated by Neoarchean granitoid rocks with lesser amounts of meta-sedimentary and associated mafic volcanic rocks. The rocks can be divided into 5 groups based on their age and geochemical characteristics: Central Slave Basement Complex rocks, Group A mafic volcanic rocks, Group B metaluminous plutonic rocks, Group C peraluminous plutonic rocks and the Dauphinee Suite. Plutonism shows a shift from metaluminous to plutonism at 2600 Ma, similar to across the Slave Province. The Nd isotopic data for all groups are consistent with the presence of ancient crust beneath only the eastern side of the Wecho River area at the time of 2608 Ma granite production. The Central Slave Basement complex is thus interpreted to extend into and terminate within the Wecho River area.