The JK area straddles the northerly trending South Unuk Shear Zone separating the upper greenschist to amphibolite facies metasedimentary and volcanic rocks of the Upper Triassic Stuhini Group from the lower greenschist grade metavolcanic and sedimentary rocks of the Hazelton Group. Large pretectonic to syndeformational elongate plutons and dikes of the Triassic to Jurassic John Peaks plutonic suite composed of hornblende diorite, monzonite, gabbro and syenite, intrude the Stuhini and Hazelton country rock.
In 1953, just northeast of the JK area, Granduc Mining Corp reported mineralization consisting of pyrite and sphalerite within narrow quartz veins within the andesite. Considerable quartz float, with pyrite, chalcopyrite and galena, also occurs several hundred metres to the west (see MINFILE showing MCK (104B 286), Assessment Report 96).
Massive chalcopyrite-magnetite boulders were discovered by Teuton Resources in the 1990s on the southern edge of the North Leduc Glacier, possibly the same as those found in 1953 by Granduc. These boulders were located during the 2006 summer program and the source was traced uphill towards the icefields on Granduc Mountain resulting in the discovery of a pyrite-magnetite calcareous breccia showing - the JK. This showing was channel-sampled, and a site located for a diamond drill platform to test for stratiform mineralization at depth.
In 2006, five drill holes (DDH-06 – 8 through 12) totalling 1240 metres were collared from a single drill platform on the north side of Granduc Mountain in order to test airborne magnetic anomalies and a possible source to massive chalcopyrite, pyrite and magnetite mineralization discovered in downslope boulder debris near the North Leduc Glacier, as well as to test the JK zone itself, exposed at surface. The lithological units of this area involve dominantly tuffaceous intermediate-mafic volcanic rocks and subordinate sedimentary rocks that possibly represent a northward extension of the Granduc Mine volcanic sequences.
All drill holes intersected a similar sequence of lithological units), with the following major lithological assemblages identified in the drilled sections, from top (W quadrant) to bottom (E quadrant) of the holes (Figures 15 to 17, Assessment Report 28912):
(a) intermediate to mafic volcanic rocks (+ argillite, siltstone and/or chert),
(b) chert (+ graphitic argillite, siltstone, and cherty tuff),
(c) breccia zone (in graphitic argillite + basalt, chert),
(d) mafic to intermediate volcanic rocks (with calcareous or Mt-bearing intervals),
(e) chloritic diorite, Mt-bearing chloritic diorite (± intermediate-mafic volcanic rocks),
(f) banded massive Mt-Cpy-Py mineralized zone,
(g) Mt-bearing intermediate-mafic volcanic rocks (tuff, flow and breccia),
(h) carbonatized intermediate-mafic volcanic rocks.
The most significant drill hole (DDH-06-09) intersected 8.08 metres (from 199.92 to 208.00 metres) grading 0.14 gram per tonne gold, 3.70 grams per tonne silver, 1.55 per cent copper, and 11.99 per cent iron (Assessment Report 28192).
The JK zone appears to lie on strike with the North zone. The JK zone is located on the northern slope of Granduc Mountain, whereas the Granduc mine is proximal to the south slope of Granduc Mountain. The zone is marked on the surface by numerous gossans of limonite and malachite stain and includes massive to banded magnetite and poddy to disseminated pyrite, pyrrhotite, and minor chalcopyrite. The host rocks of the JK zone vary from banded chert and graphitic argillite to mafic flows and iron formation, similar to the rocks in Unit 3v1, the unit of the Granduc mine series that hosted most of the Granduc ore.
The exposed dimensions of the new discovery at surface are approximately 30 metres in length by six metres in width. Snow and ice conceal the south end of the zone. An angular till boulder of massive, banded magnetite, with thin laminations of pyrite and chalcopyrite suggest that similar mineralization is present in the up-ice (strike) direction.
The continuity of magnetite-pyrrhotite-chalcopyrite mineralization across a four-kilometre strike length is reported to place Granduc in the top percentiles of Besshi-style VMS deposits.
GENERAL WORK HISTORY
Granby Mining company did the first systematic surface and underground exploration in 1952, but development did not take place until a joint venture by ASARCO and Newmont Mining Corporation Ltd were able to finance the challenging work needed to put the deposit into production. Mine development commenced in the early 1960s punctuated by the February 18, 1965 avalanche disaster in the Leduc camp. Production began in 1968 utilizing the 18-kilometre Tide tunnel connecting the mine workings to the upper Salmon River valley to produce 2000 tpd of copper ore. Production ceased in 1977 because of low metal prices. In 1979 the mine was acquired by Esso Minerals Canada Ltd and operated until closure in May 1984. Following the closure in 1984 the property remained dormant and the mill structure at Tide Lake was removed after heavy snow collapsed the roof.
In the 90s various localized exploration efforts by Hecla Mining Company coincided with academic studies by the Mineral Deposits Research Unit (MDRU) of the University of BC.
In 2004 the patented mining claims covering the Granduc mine property were purchased by Glenn Zinn and transferred to Bell Resources Corp. Subsequent staking by Teuton Resources surrounded the crown grants and their claims were in turn enclosed partially by Bell Resources claims. The Teuton Resources claims were optioned by Bell in 2005 and exploration work began continued through to 2006.
In 2010, Castle Resources acquired the Granduc property from Bell Copper Corporation. Castle continuously conducted exploration on the property from summer 2010 to summer 2015.
In 2016, the Granduc property was put under care and maintenance until market conditions improved or a strategic partner was found to carry on exploration and development activities.
Refer to Granduc (104B 021) for further geological information and a more detailed work history and related bibliography.
