| The NICO iron-oxide associated polymetallic sulphide deposit is located at the southern end of the Great Bear Magmatic Zone. The immediate area of mineralization near Lou Lake occurs in a northwest-trending volcano-sedimentary belt, extending from the Wopmay fault at Ray Rock to Mazenod Lake. At the site of mineralization the Paleoproterozoic Snare Group, deposited prior to the emplacement of the Hepburn intrusive suite (1900–1880 Ma) consists of lower thin-bedded siltstone, middle amphibolitic ironstone and upper quartz arenite. Northwest of Lou Lake the Snare Group rocks are overlain by Lou Lake felsic ash flow tuffs, an arm of the Faber Lake Group. The contact between the Snare and Lou Lake groups is a breccia zone, enveloping massive felsite and juxtaposing cordierite facies metasediments against nonmetamorphosed volcanics. The polymetallic mineralization, occurring below volcanics, is hosted by “black rock” altered middle Snare, characterized by alternating beds of amphibolitic ironstone and quartz arenite with subordinate marl, dolomitic marble and siltstone. (Abstract shortened by UMI.)... |
