Abstract
The compositions of phyllosilicates, with a focus on fluid-mobile elements, were evaluated as a means to fingerprint the Middle Ordovician metamorphosed (greenschist facies) volcanogenic massive sulfide deposits of the Bathurst Mining Camp (BMC), Canada. Ninety-five drill-core samples from six of the major deposits of the Bathurst Mining Camp (Brunswick No. 12, Heath Steele B zone, Halfmile Lake Deep zone, Key Anacon East zone, Louvicourt, and Restigouche) were analyzed using electron microprobe and laser ablation inductively coupled plasma-mass spectrometry. Typically, phyllosilicates (chlorite, white mica, and to a lesser extent biotite) are ubiquitous phases in the host rocks of the massive sulfide deposits of the BMC. Electron microprobe analysis results show a wide compositional variation in chlorite and white mica. Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis was performed to measure fluid-mobile elements, showing that Tl is distinctly enriched in all white mica (up to 719 ppm) relative to chlorite (up to 50.1 ppm). Chlorite hosts Sn (up to 4600 ppm), Hg (up to 7.3 ppm), Sb (up to 35.4 ppm), As (up to 1320 ppm), In (up to 307 ppm), Cd (up to 83.2 ppm), and Se (up to 606 ppm). White mica hosts Sn (up to 1316 ppm), Hg (up to 93 ppm), Sb (up to 1630 ppm), As (up to 14,800 ppm), In (up to 1186 ppm), Cd (up to 98 ppm), and Se (up to 38.8 ppm). Limited LA-ICP-MS analysis on biotite indicates a higher overall concentration of Tl (mean = 14.6 ppm) relative to co-existing white mica (mean = 2.18 ppm). On average, biotite is also more enriched in Hg, Sn, and Ba relative to chlorite and white mica. Laser Ablation ICP-MS profiles of chlorite, white mica, and biotite demonstrate smooth time-dependent variations diagnostic of structural substitution of these elements. Compositional variation of chlorite-white mica pairs presented in the current study shows systematic variations as a function of distance from the mineralized horizons. This highlights the potential to use trace-element signatures in these phyllosilicate pairs to identify proximal (chlorite) and distal (white mica) footprints for volcanogenic massive sulfides exploration.
Highlights
The volcanogenic massive sulfide deposits are major sources of Zn, Cu, Pb, Ag, and Au, and significant sources of Co, Sn, Se, Mn, Cd, In, Bi, Te, Ga, and Ge
Chlorite is ubiquitous in the Bathurst Mining Camp (BMC) and is a major component of exhalative sedimentary rocks, including Algoma-type iron formation and in chloritic tuff in areas distal to mineralization
This study documents the concentrations of fluid-mobile elements within phyllosilicates from the alteration zones of several VMS deposits of the Bathurst Mining Camp, Canada
Summary
The volcanogenic massive sulfide deposits are major sources of Zn, Cu, Pb, Ag, and Au, and significant sources of Co, Sn, Se, Mn, Cd, In, Bi, Te, Ga, and Ge. Minerals 2019, 9, 125 leaching of footwall rocks or supplied directly from magmatic fluids. The metal-bearing hydrothermal fluid migrates to the site of deposition (seafloor) via convective up-flow. Mineralogical changes in the footwall rocks (e.g., distal white mica to proximal chlorite, depending on the massive sulfides subtypes) are symmetrically zoned about the up-flow conduit and define distinct alteration haloes [1]. These haloes are commonly more extensive than their respective deposits thereby providing a larger (up to several km radiuses) target area within which mineralization may exist. The primary challenge is discriminating mineralized from barren alteration systems and recognizing the fringes to ore horizons
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
