Linkages and systematics of A-type magmatism, alkali alteration and magnetite mineralization of the Nonacho Basin, Northwest Territories

Abstract

1 online resource (267 pages) : illustrations (some colour), maps (some colour), charts (some colour), graphs (some colour)Includes abstract and appendix.Includes bibliographical references (pages 191-203).The Nonacho Basin, located in the southwestern Rae Craton, Northwest Territories, hosts widespread polymetallic mineralization (Cu-Pb-Zn-Ag-U-Th-Mo) and structurally controlled alkali alteration (e.g., albitization and potassic alteration) associated with Fe-oxide mineralization. Field evidence suggests that this alteration is at least partially linked, both spatially and temporally, to the 1830 - 1790 Ma A-type magmatism of the Thekulthili Stock. A petrographic, geochemical, and geochronological study of the Thekulthili Stock characterizes the intrusion, constrains the alteration systematics, and provides a geodynamic context for this magmatism. Magnetite, a ubiquitous Fe-oxide phase of the Nonacho Basin, occurs across various rock types that are locally overprinted by alkali alteration. Distinct magnetite types are classified based on host rock, mineral associations, and paragenesis, with trace element chemistry used to infer their origin. These findings are integrated to assess the region's potential for Metasomatic Iron and Alkali Calcic - related deposits