Structural Reconstruction of the Flin Flon Volcanogenic Massive Sulfide Mining District, Saskatchewan and Manitoba, Canada

Abstract

The Flin Flon mining district is part of a greenstone belt, the Flin Flon-Glennie Complex, in the Paleoproterozoic Trans-Hudson orogen. Its tectonic history began prior to 1872 Ma with the development of regional folds—the faulted F1 Burley Lake syncline and F2 Hidden Lake syncline—during D1 and D2 intraoceanic accretion of the 1888 Ma Flin Flon arc to other volcanic terranes. Amalgamation of the Flin Flon to Glennie terrane, possibly during D3, produced a W-propagating thrust-fold belt and basins in which fluvial sedimentary rocks were deposited between 1847 Ma and 1842 Ma. As the fold-thrust belt migrated westward, these rocks were incorporated into a stack of E-dipping thrust sheets bounded by NNW-striking thrust faults (1920 fault) and internally folded by W-verging folds (Pipeline, Mud Lake, and Grant Lake synclines). Subsequent D4 collision of the Flin Flon-Glennie Complex with the Archean Sask microcontinent was broadly coeval with but outlasted the emplacement of 1840 Ma Phantom Lake dikes. D4 produced a second truncating fold-thrust system characterized by N-directed thrust faults (Club Lake and Railway faults) and E-trending folds (Flin Flon Creek syncline). These folds were overprinted by two regional cleavages, and the thrust faults were reactivated as oblique-slip shear zones, either late during the same collisional event (D5) or during terminal collision (D6) of the Sask craton and Flin Flon-Glennie Complex with the Superior craton at 1.83 to 1.79 Ga. The Flin Flon volcanogenic massive sulfide ore system was thrust-imbricated during D3 and D4, and ore lenses were stretched parallel to a regional, SE-plunging, stretching lineation that formed during D4 and was later modified during D5.