Matteo Clemente, MSc
M. Clemente1, M. Hannington1
1Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Ontario, Canada
The Kidd Creek deposit is a high-grade high tonnage Archean Cu-Zn volcanogenic massive sulfide (VMS) deposit hosted in the Kidd-Munro Assemblage within the Western Abitibi Greenstone Belt. This deposit contained several complex zones in the different orebodies of the system with highly variable arsenic contents in different minerals, from 800-1,000 ppm in both sphalerite ore and chalcopyrite ore to nearly 3,000 ppm in bornite-rich ore. The arsenic occurs in seven unique minerals: arsenopyrite, cobaltite, tennantite, enargite, colusite, cattierite, and vinciennite. Microprobe analysis indicates minor amounts of arsenic are also present in solid solution in pyrite throughout the deposit (1400 ppm average; generally increasing from Zn-rich to Cu-rich ore). Arsenic in the bulk samples show the strongest correlation with Co in cobaltite. In addition to arsenopyrite (45 wt.% As), arsenic is present in cobaltite (40 wt.%), tennantite (20 wt.%), enargite (19 wt.%), colusite (9 wt.%), cattierite (6 wt.%), and vinciennite (5 wt.%). Twenty-two thin sections were created from samples containing over 300 ppm As, collected from various depths of the deposit. These samples are being analyzed using reflected light microscopy, scanning electron microscopy (SEM), and laser ablation inductively coupled plasma mass spectroscopy (LA-ICPMS) to constrain the distribution of arsenic-bearing minerals and their origins. For example, high concentrations of arsenic in the bornite zone, and more specifically within the tennantite-rich contact zone, strongly indicate metamorphic remobilization during recrystallization of the Cu-rich minerals (e.g., as a product of exsolution from nonstoichiometric solid solutions). Constraining the behavior of arsenic and the distributions of As-bearing minerals at Kidd Creek allows for a better understanding of the paragenesis and conditions of arsenic mineralization in other VMS deposits.