| Regional
Geology
The Kerr-Sulphurets property lies within the Stikine Terrane and is underlain
largely by Upper Triassic to Middle Jurassic Hazelton Group volcanic, volcaniclastic
and sedimentary rocks at the western edge of the Bowser Basin. At least three
intrusive episodes have been documented in the area. The most important of
these relative to mineralization appears to be felsic to intermediate plugs,
small stocks and dykes. In the Sulphurets area, these intrusions are referred to
as the Mitchell Intrusions; many of the intrusions are intensely altered and cut
by faults.
The property is centred along the axis of the broad northerly plunging McTagg
anticlinorium which forms the major structural element in the region. The Upper
Triassic Stuhini Group argillaceous and turbiditic sedimentary rocks form the centre
for the anticlinorium. These rocks are flanked by a younger volcanic sequence forming
the Betty Creek, Unuk River and Mount Dilworth Formations of the Hazelton Group. Within
this geologic framework, copper, gold and molybdenum mineralization and associated
alteration are focussed in a local core of the anticlinorium where intense folding,
faulting, thrust faulting and intrusions are prevalent.
A number of deformed porphyry and vein type deposits occur in the Mitchell-Sulphurets
area. These deposits are characterized by a strong copper-gold and minor molybdenum
association, and spatially occur along the flanks of a horseshoe-shaped trend.
A distinct mineral zoning pattern can be interpreted with gold-silver along the eastern
flank, gold with minor copper and molybdenum at the north end, gold and copper along
the west flank and copper with lesser gold at the southwest end.
Sulphurets Gold Zone Geology
Disseminated copper-gold mineralization in the Sulphurets Gold Zone is centred
about a hydrothermal breccia (Breccia Gold Zone) and dyke complex
(Raewyn Copper-Gold Zone) representing the higher levels of a monzonite-related
copper-gold porphyry system. The zone trends northeasterly and lies in strongly
altered and fractured volcanic and immature sedimentary rocks of the Hazelton
Group below the Sulphurets Thrust Fault. Copper and gold mineralization in the
Sulphurets Gold Zone is concentrated within a potassic feldspar alteration halo
centred about intensely altered hydrothermal breccias and monzonite dykes. Features
of these rocks have been largely overprinted by later silicification (including
siliceous hydrothermal pipes) in the Breccia Gold Zone and strong biotite, silica
and local chlorite-albite alteration in the Raewyn Copper-Gold Zone. Both zones are
enveloped by a broad halo of phyllic quartz-sericite-pyrite alteration
along the length of the Raewyn structural panel. Alteration overprinting in proximal
areas was accompanied by significant local remobilization of copper and gold. Later
faulting within the Raewyn panel was probably associated with regional scale Cretaceous
compression and has further complicated the geologic relationships. The combined gold
(>340 ppb) and copper (>1000 ppm) lithogeochemical anomaly associated with the
Sulphurets Gold Zone Target has a strike length of 2.5 kilometres by up to one kilometre
in width.
The Sulphurets Gold Zone contains two distinct styles of gold-copper mineralization
which are central to a complex series of overlapping hydrothermal alteration zones.
The Breccia Gold Zone contains gold in the 2.0 g/t Au to 4.0 g/t Au range, minor copper
and, possibly, an association between gold and coarse pyrite. The Raewyn Copper-Gold
Zone has a significant copper content as chalcopyrite with closely associated gold and
local molybdenum mineralization. Values in the range of 0.30% Cu to 0.80% Cu and 0.40
g/t Au to 1.00 g/t Au are common.
The Sulphurets Gold Zone trends northeasterly and sub-parallel to the Sulphurets
Thrust Fault. The zone which has a relatively shallow northwesterly dip with variable
widths of between 75m to 200m has been defined by drilling over a strike length of 1,000m.
It is open to the southwest; a lithogeochemical anomaly indicates the potential extension
of this zone towards the Sulphurets Lake Gold Zone for at least another one kilometre.
Kerr Geology
The Kerr deposit extends approximately 3,000 m in a northerly trend from the crest
of a ridge above the southwestern branch of the Sulphurets Glacier down to the
lower slopes of a cirque-like basin just above Sulphurets Lake. A large strongly-leached,
schistose pyritic gossan is developed along the face of the cirque.
The Kerr deposit is a pyrite-rich copper-gold system that has been developed in
strongly altered and deformed monzonitic intrusions in Stuhini Group sedimentary and
volcaniclastic rocks. Alteration and mineralization are characterized primarily by
variable amounts of sericite, chlorite, quartz, anhydrite, pyrite and chalcopyrite.
The most important mineralization type is quartz stockwork with associated pyrite,
chalcopyrite, bornite, tetrahedrite and rare enargite. The strongest copper-gold
mineralization is associated with a core of chlorite-bearing alteration and quartz
stockwork. Strong phyllic alteration with quartz and disseminated pyrite flanks the
core zone.
A total of 144 diamond drill holes were completed on the Kerr deposit during the
period 1985 to 1992. The deposit is primarily defined by its copper content in a
50° to 60° westerly dipping, 100 to 150 m wide, 1,900 m long zone, that extends
to depths of 350 m below surface. Vertically, the mineralization has been defined on
surface from an elevation of 1150 m at the base of the cirque to elevation 1750 m at
the crest of the cirque.
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