Publication Type:
Book ChapterSource:
Geological Society of America, 2011 annual meeting, Geological Society of America (GSA), Boulder, CO, United States, Volume 43, p.633 (2011)ISBN:
0016-7592Keywords:
absolute age, Baffin Island, Canada, carbonate rocks, dates, Devonian, eastern canada, Fluid inclusions, host rocks, inclusions, lead ores, lead-zinc deposits, metal ores, mineral assemblages, mineral deposits, genesis, mineralization, neoproterozoic, Nunavut, ore-forming fluids, paleomagnetism, paleosalinity, Paleozoic, Precambrian, proterozoic, Re/Os, Sedimentary rocks, SEM data, silver ores, Temperature, upper Precambrian, zinc ores, zoningAbstract:
The world class Nanisivik Zn-Pb(Ag) deposit is hosted by carbonate rocks of the Proterozoic Nanisivik Formation on Baffin Island, Nunavut. MVT deposits like Nanisivik contain few datable minerals and as such, the timing of fluid flow and related sulfide mineralization is not well constrained. At Nanisivik, a variety of possible ages have been proposed including: ca. 1095 Ma based on paleomagnetism of the host rock, assumed to record the hydrothermal activity associated with mineralization (Symons et al., 2000), and ca. 460 Ma based on Ar-Ar dating of adularia alteration (Sherlock et al., 2004). We applied Re-Os geochronology using pyrite to constrain the timing of sulfide mineralization at Nanisivik and similar mineralization at Hawker Creek, 30 km to the SE. Ten pyrite analyses at Nanisivik yield an age of 1114 + or - 120 Ma, but with considerable scatter in the data. New fluid inclusion data for sphalerite using IR microscopy from the main ore zones indicate the dominant fluid inclusion assemblage (L-V type) has Th values of 300 degrees C and 200-275 degrees C occur and may reflect post entrapment heating by Franklinian-aged dikes (ca 720 Ma) and local methane production, respectively. At Hawker Creek highly radiogenic pyrites were used for age constraints. These Model Ages show a large range from > 900 Ma to ca. 400 Ma. We interpret these Re-Os pyrite and fluid inclusion data to indicate primary mineralization at Nanisivik from a low T ( 900 Ma, but with evidence for much younger (ca 400 Ma) pyrite formation within the Nanisivik Fm. References: Sherlock, R. L., et al., 2004, Geologic and geochronologic constraints on the timing of mineralization at the Nanisivik zinc-lead MVT deposit, northern Baffin Island, Nunavut, Canada. Econ. Geol. 99, 279-293. Symons, D. T. A., et al., 2000, Paleomagnetism of the Society Cliffs dolostone and the age of the Nanisivik zinc deposits, Baffin Island, Canada: Min. Dep., 35, 672-682
Notes:
GeoRef, Copyright 2018, American Geological Institute.<br/>2013-051404<br/>Franklinian<br/>Hawker Creek Deposit<br/>Nanisivik Deposit<br/>Nanisivik Formation
