Geology, geochronology, and metallogeny of High Lake greenstone belt, Archean Slave Structural Province, Northwest Territories

Abstract

High Lake greenstone belt, mapped along strike for 100 km, is subdivided into three domains based on lithological association, results of U-Pb zircon dating of volcanic rocks, and distribution of mineral occurrences. The oldest volcanic rocks (ca. 2.70 Ga) are felsic and predominate in the Western domain. Younger basaltic, andesitic, and dacitic flows and tuffs (ca. 2.67 Ga) are observed in the Eastern domain. The youngest rock interpreted to be volcanic, mapped in the Central domain, is a dacite (ca. 2.62 Ga) at the contact between greywacke and graphitic-sulphidic slate and siltstone. The belt is surrounded and intruded by 2.62-2.58 Ga granitic plutons and batholiths. In the Western and Eastern domains, synvolcanic massive sulphides occur in intermediate to felsic volcanic rocks. In the Western domain, zones of hydrothermal alteration ("dalmatianite") are indicated by porphyroblastic knots of quartz-sericite-chlorite or cordierite. In the Central domain, epigenetic gold occurs with arsenopyrite-quartz in dilatant zones in mafic volcanic as well as metasedimentary rocks.