Evidence for an MIAC-U system in the Kiggavik Region, Nunavut, Canada
The Kiggavik, Bong, End, and Andrew Lake uranium (U) deposits, hosted just outside of the margin of the Thelon Basin, Nunavut, are often considered unconformity-related deposits similar to U deposits of the Athabasca Basin, Saskatchewan. New data reveals a complex alteration paragenesis including albitization, brecciation, silicification, hematization, and sericitization of host rocks, and the presence of Fe-Pb-Cu-Mo sulfides, native Au and Bi, Bi ± Cu sulfides/selenides/tellurides, Be-silicates, and barite in addition to U oxides and silicates including brannerite and hydrothermal zircon. Geochronology indicates primary mineralization is synchronous with potassic igneous activity in the region. Although the geochronology, structural controls, and some aspects of mineralogy are generally consistent with basement-hosted unconformity-related U deposits in the Athabasca Basin, they are also consistent with Metasomatic-Iron-Alkali-Calcic (MIAC)-style mineralization. The early albitization, unusual polymetallic U mineralization, absence of dravite, and strong spatial and temporal links to magmatic-hydrothermal processes favors the MIAC model.