Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

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Porphyry Mo and Cu-Mo Deposits Associated with
Nanika Intrusions of Nanika Plutonic Suite
The Eocene Nanika Plutonic Suite, which forms the most widespread suite of post-accretionary granitoid plulom
intruding the Stikinia terrae, include the Nanika Intrusions south of Bowser Basin (Carter, 1982), and the Alice Arm Inbusions
west of the basin (Woodsworth and others, 1991). The small, multi-stage, calc-alkaline granitic to granodiorite stocks, dikes and
sills, which were intruded along steeply-dipping faults, are interpreted to be the roots of deeply-eroded volcanic centers, perhaps
of the Hazelton Group (Maclntyre, 1985). Several major porphyry deposits associated with Nanika Intrusions occur northeast of
Hazelton, B.C. The largest of these deposits are at Berg, Mount Thomlinson, and Redbird. Other significant deposits in the Huston
district are at Lucky Ship porphyry Mo and Nanika Mountain porphyry Cu (Mo) deposits. The Serb Creek porphyry Mo and the
Big Onion porphyry Cu-Mo deposits (Wojdak and Stock, 1995) occur east and west of Smithers, respectively
Berg Porphyry Cu-Mo (Pb-Zn-Ag-Au) Deposit
The Berg porphyry Cu-Mo (Pb-Zn-Ag-Au) deposit consists of chalcopyrite, molybdenite and pyrite with minor
sphalerite, gakna, and arsenopyrite (Panteleyev, 198 1; EMR Canada, 1989; Dawson and others 1991). Estimated reserves are 238
million tomes grading 0.39% Cu, 0.05% MoS2, 2.84 g Ag. The deposit occurs within a fine-grained slwkwork of quartz veinlets
which are distributed in a broad asymmetrical zone around a semicircular quartz-monzonite porphyry stock of the Eocene Nanika
Suite, and within the peripheral, contact-metamorphosed volcanic rocks of the Hazelton Group. The most intense Mo
concentrations occur in the stock whereas the most intense Cu concentrations occur 60 meter beyond the contact. A pyrite birlo
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Mount Thornlinson Porphyry Mo Deposit
The Mount Thomlinson porphyry Mo deposit consists of molybdenite, chalcopyrite, along with minor magnetite and
scheelite which occur in a stockwork of quartz veinlets near the northwest contact of a circular, Eocene quartz monzonite
porphyry stock which intrudes argillaceous Jurassic sedimentary rocks (Carter, 1982; EMR Canada, 1989). Estimated reserves are
40.8 million tonnes grading 0.12% MoS2. The deposit occurs predominantly within intrusive rocks along the northwest contact.
The host sedimentary rocks are deformed and metamorphosed into biotite, muscovite, cordierite, and andalusite-bearing schists.
Redbird Porphyry Mo Deposit
The Redbird porphyry Mo deposit consists of molybdenite and pyrite which occur in a stockwork of quartz veinlets
within peripheral, concentric alteration zones of a quartz-monzonite porphyry stock of the Eocene Nanika Suite which intrudes
Middle Jurassic pyroclaslic rocks of the Hazelton Group (EMR Canada, 1989; Dawson and others, 1991). Estimated reserves are
63.5 million tonnes grading 0.17% MoS2.The stock is dominantly one phase, and hosts a peripheral ring of molybdenum. Also
present are polessic (K-feldspar), silica-sericite, and kaolinite alteration are present. The stock has a K-Ar isotopic age of 49.0 Ma.
Porphyry Mo Deposits Associated with
Alice Ann Intrusions of Nanika Plutonic Suite
The Alice Arm Intrusions of the Nanika Plutonic Suite, which occur along the eastern margin of the Coast Plutonic
Complex, consist of small granite to quartz monzonite porphyry stocks which intrude clastic rocks of the Late Jurassic Bowser
Assemblage at the Intersections of north-northwest and east-northeast faults (Carter, 1982). The major porphyry deposits are the
Ajax porphyry Mo, Bell Moly porphyry Mo-W, and Kitsault (B.C. Moly) porphyry Mo (Ag, Pb, Zn, Cu) deposit.
Ajax Porphyry Mo Deposit
The Ajax porphyry Mo deposit consists of molybdenum in a quartz-vein stockwork which is hosted in an Eocene quartz
monzonite porphyry intrusion, and in adjacent, contact-metamorphosed Jurassic argillaceous rocks (Soregaroli and Sutherland
Brown, 1976; ENLR Canada, 1989; MINFILE, 2002). The deposit occurs in four small, closely-spaced plutons. Estimated reServ&
are 178.5 million tomes @ng 0.12 1 % MoS2. Total reserves are 4 17.3 million tonnes grading 0.099'0 MoS2 with a very high
stripping ratio. The porphyry intrusion exhibits a K-Ar biotite isotopic age of 54.0 Ma age.
Bell Mdy Porphyry Mo-W Deposit
The Bell Moly porphyry Mo-W deposit consists of molybdenite and minor scheelite which occur in a quartz vein
stockwork in an Eocene quartz monzonite porphyry and in adjacent biotite homfels in Jurassic metasedimentary and metavolcmic
rocks (Carter, 1982; EMR Canada, 1989). Estimated reserves are 106 million tonnes grading 0.09% Mas. The deposit occurs in a
crescent-shaped zone around the eastern portion of the stock.