The
KSM project located 65 km northwest of Stewart, British Columbia. Exploration
of the project began in 2006 and proven and probably reserves currently total
38.2 million ounces of gold and 9.9 billion pounds of copper. The KSM project
comprises four deposits, Mitchell, Iron Cap, Sulphurets and Kerr.
Rather
than a single stock, mineralisation at KSM occurs within a gold-enriched copper
porphyry system controlled by a series of high-level monzonitic dykes, sills
and plugs, collectively referred to as the ‘Mitchell Intrusions’. These
intrusions are hosted within volcanic rocks of the Jurassic Hazelton Group and
are in fault contact with silicious hornfels sedimentary and intermediate
volcanic rocks of the Upper Triassic Stuhini Group. All lithologies are altered
as a result of a relatively shallow, long-lived hydrothermal system generated
by the monzonite intrusion.
The
Mitchell zone is exposed in an erosional window below the Mitchell thrust fault
which truncates the upper part of the deposit. The deposit comprises schistose
rocks with abundant sericite, disseminated pyrite and a strongly deformed
quartz stockwork. In the core of the Mitchell deposit, quartz veins constitute
more than 50% of the rock, with chalcopyrite being the principal copper
mineral, and grades of both copper and gold in remarkably uniform occurrences.
2
km south of the Mitchell zone, the Sulphurets deposit occurs at structurally
higher levels between the Mitchell and Sulphurets thrust faults. Mineralisation
is structurally stacked in this area, although the principal Sulphurets zone is
a moderately developed quartz stockwork that is cross-cut by a higher grade
hydrothermal breccia zone. The north-dipping Sulphurets thrust fault truncates
the top of the deposit.
Mineralisation
in the Kerr area forms a mostly continuous, north-south trending and westerly
dipping, irregular body at least 1700 m long, and up to 200 m thick. Higher
grades are associated with crackled quartz stockwork, anhydrite veining, and
chlorite alteration. It is enveloped by a schistose, pyrite rich phyllic
alteration with low to moderate grades. Mineralization is open at depth and
along strike.
(Source:
P. Wojdak, 2009. Northwest Region. www.em.gov.bc.ca
Accessed: 30/07/12)
