Publication Type:

Miscellaneous

Authors:

Ordóñez-Calderón, J. C.; Lafrance, Bruno; Gibson, Harold L.; Schwartz, T.; Pehrsson, Sally J.; Rayner, Nicole M.

Source:

A special issue on volcanogenic massive sulfide deposits of the Trans-Hudson Orogen, Economic Geology Publishing Company, Lancaster, PA, United States, Volume 111, p.817-847 (2016)

ISBN:

0361-0128

Keywords:

andesites, argillite, asthenosphere, basalts, Canada, Canadian Shield, chemical composition, clastic rocks, copper ores, crust, dikes, facies, felsic composition, Flin Flon Belt, foot wall, gabbros, geochemistry, geodynamics, geologic thermometry, gold ores, greenschist facies, hanging wall, high temperature, Hudsonian Orogeny, Hydrothermal alteration, igneous rocks, intrusions, lead ores, lithogeochemistry, magmatism, Manitoba, massive deposits, massive sulfide deposits, melting, metal ores, Metamorphic rocks, metamorphism, metasomatism, mineral deposits, genesis, mineralization, North America, oceanic crust, Paleoproterozoic, plate tectonics, plutonic rocks, Precambrian, proterozoic, reconstruction, resources, rhyolites, rifting, Sedimentary rocks, sills, silver ores, Temperature, upper Precambrian, volcanic rocks, Western Canada, zinc ores

Abstract:

The Trout Lake deposit (1878 + or - 1 Ma) is a rhyolite-hosted, bimodal-mafic, volcanogenic massive sulfide (VMS) deposit. It is one of the largest VMS deposits in the Flin Flon mining district, containing 21.8 Mt of Cu-Zn rich ore. The deposit underwent greenschist facies metamorphism and polyphase synvolcanic to postvolcanic hydrothermal alteration. Footwall and hanging-wall lithostratigraphic units of the Trout Lake deposit occur as an upright, steeply NE dipping, homoclinal succession of thrust-repeated volcanic and siliciclastic sedimentary units. The deposit consists of several massive sulfide ore lenses hosted within a felsic volcanic unit that represents a localized felsic eruptive center composed of flows, synvolcanic sills, and volcaniclastic lithofacies with an FIIIb-type tholeiitic to transitional rhyolite composition (Zr = 213-385 ppm; Yb (sub cn) = 47-100; La/Yb (sub cn) = 0.97-2.33). The felsic unit occurs along strike of an andesitic unit comprising an intercalation of high-MgO andesite (MgO > 5.0 wt %) and Nb-enriched andesite (Nb = 10-13 ppm) flows that are underlain by a footwall basaltic unit composed of flow lithofacies with a low-Ti tholeiitic basaltic composition (TiO (sub 2) 1.45) variably affected by slab-derived hydrous melts. These petrologic characteristics suggest a geochemically heterogeneous mantle wedge that underwent metasomatism by slab-derived components. In addition, zircon saturation thermometry indicates that FIIIb-type rhyolites formed at temperatures >900 degrees C during partial melting of mafic lower crust. Collectively, the occurrence of high-temperature melts indicates that the Trout Lake VMS deposit formed in a hot, intraoceanic, extensional-arc geodynamic setting. Intra-arc rifting, asthenospheric upwelling, and subduction of young and hot oceanic crust are mechanisms that explain the high-temperature magmatism and are features consistent with the formation of the massive sulfide ore lenses. The back-arc basalt geochemical signatures of the postvolcanic gabbros suggest that the tectonic environment of the Trout Lake area evolved from an intra-arc rift, during the deposition of the ore lenses, to an incipient back-arc basin during the intrusion of the gabbros.

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>2016-070925<br/>Trout Lake Deposit