|Title||Gold mineralization in the Cantung W-skarn deposit, Northwest Territories: an examination of distribution, mineralogy, and petrogenesis|
|Download||Download (whole publication) |
|Author||Palmer, E M; McFarlane, C R M; Lentz, D R; Falck, H|
|Source||TGI 4 - intrusion related mineralisation project: New vectors to buried porphyry-style mineralisation; by Rogers, N (ed.); Geological Survey of Canada, Open File 7843, 2015 p. 415-428, https://doi.org/10.4095/296480 (Open Access)|
|Links||Canadian Database of Geochemical Surveys, downloadable
|Links||Banque de données de levés géochimiques du Canada,
|Publisher||Natural Resources Canada|
|Related||This publication is contained in Rogers, N; (2015). TGI 4 -
Intrusion Related Mineralisation Project: new vectors to buried porphyry-style mineralisation, Geological Survey of Canada, Open File 7843|
|Related||This publication is related to Chapman, J B; (2014).
Mineralogy and chemistry of tourmaline in the Woodjam porphyry deposits, British Columbia, Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 37|
|Lat/Long WENS||-128.0000 -126.0000 61.0000 60.0000|
|Subjects||economic geology; mineralogy; porphyry deposits; porphyry copper; mineral exploration; mineralization; alteration; tungsten; molybdenum; gold; skarn deposits; petrogenesis; petrography; Cantung
|Illustrations||location maps; photographs; plots; photomicrographs; plots|
Geoscience Initiative (TGI-4), Intrusion/Porphyry Ore Systems|
|Released||2015 06 11|
|Abstract||The Cantung mine is a world-class W-skarn deposit; it is located just east of the Yukon border in the Selwyn Mountain Range of the Northwest Territories. The deposit area is within the southern extent
of the polymetallic Tintina Gold Belt, which has many notable intrusion-related Au deposits. The extensive W skarns at Cantung were developed by hydrothermal fluids that, based on earlier research, were determined to be predominately supercritical
magmatic brines with homogenization temperatures ranging from 270-500°C. Mineralization is composed of calcic exoskarn replacement of a clean limestone and lower grade replacements in a calc- silicate/chert unit; these occur in both the operating
open pit and underground mine (the E Zone). The main sulphide identified petrographically is pyrrhotite, which is abundant in all skarn facies. Scheelite and chalcopyrite are dominant and there is locally abundant sphalerite. Native Bi exhibits
textures indicative of forming later than the silicate assemblage in the paragenetic sequence, and it is decorated by bismuthinite, Bi tellurides, Ag tellurides, and Bi selenides. Tungsten and Cu are the main mine products, but the Au potential of
the deposit merits further investigation.|
This study characterized the distribution, mineralogy, and petrogenesis of Au mineralization by examining five skarn samples with bulk rock Au assay values >0.5 ppm taken from the E Zone. No free gold or
electrum were identified petrographically or by SEM and FEG- SEM analyses. A positive correlation (Spearman's Rank, r') of Au with Bi (0.76), Ag (0.70), Fe (0.64), Cu (0.64), and Mo (0.60) was identified using the bulk rock geochemical data (n = 48).
The strong correlation between Bi and Au is suggestive of a liquid bismuth collector mechanism for Au enrichment. However, LA ICP-MS analysis of native Bi and Bi alloys failed to reveal significant Au predicted by the liquid bismuth collector model.
In contrast, the highest Au concentration was encountered in hessite (Ag2Te) and other tellurides. Nano-inclusions within chalcopyrite and silicate minerals were also investigated using FEGSEM for their Au content, but their composition consisted of
native Bi. The decoration of native Bi by bismuthinite, Bi tellurides, Ag tellurides, and Bi selenides provides evidence for a late stage S-, Ag-, and Te-rich fluid. This fluid is thought to have remobilized the Au and deposited it as lattice bound
invisible Au within the tellurides. This new data constrains Au exploration targets at Cantung to areas of altered skarn or where there is a presence of telluride minerals.