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

terrane (Eastfield Resources Ltd., News Releases of October, 28, November 4, December 1, 1987). The deposit and sheared rocks
occur along a splay of the Pinchi Fault.
Origin of and Tectonic Controls for
Pinchi Lake Metallogenic Belt
The deposits in the Pinchi metallogenic belt postdate the host bedrock units, both the Late Triassic blueschist of the
Cache Creek terrane and overlying Late Cretaceous and early Tertiary conglomerate (Paterson, 1977). The deposits occur in
shears along the Pinchi Fault which separates the Mississippian to Triassic Cache Creek terrane from the Late Triassic Quesnellia
island-arc terrane. The fault is interpreted as providing a zone of permeability for mercury-bearing hydrothermal solutions
(Dawson and others, 199 1). Reactivation and shearing along the fault, and formation of the deposits may have occurred during a
period of uplift, magmatism, and transcurrent faulting in the Eocene and Oligocene (Gabrielse, 1985), possibly related to the
Cascade volcanic-plutonic belt to the south. No known Eocene or Oligocene intrusions exist in the region.
Owl Creek Metallogenic Belt of Porphyry Cu-Mo,
Porphyry Mo, and Au Polymetallic Vein Deposits
(Belt OC) Southern British Columbia
The Owl Creek metallogenic belt of porphyry Cu-Mo, porphyry Mo and Au polymetallic vein deposits (fig. 103; tables 3,4)
occurs in southern British Columbia and is associated with a belt of late Tertiary plutons which extends from northern Washington
into the Coast Plutonic Complex. The plutons are mostly small, circular quartz monzonite to dioirite plugs which intrude major,
northwest-trending shear zones. These granitoid rocks are part of the middle Tertiary to Recent Cascade continental-margin arc
which occurs in the USA Pacific Northwest and southern British Columbia (Nokleberg and others, 1994c, 1997c; Monger and
Nokleberg, 1996). The significant deposits in the belt are the Owl Creek district porphyry Cu-Mo deposits, and the Clear Creek
(Gem) porphyry Mo deposit (table 4) (Nokleberg and others 1997% b, 1998). The deposits in the Owl Creek metallogenic belt are
hosted in or near: (1) calc-alkaline, high-level plutons of the Chilliwack suite which is part Chilliwack Batholith on the British
Columbia-Washington border; and (2) the Doctor's Point pluton on Harrison Lake which is coeval and probably cogenetic with
the Pemberton belt of late Tertiary volcanic rocks (Souther, 1991; Woodsworth and others, 1991). The significant deposits are at:
Clear Creek (Gem), Owl Creek district, and Salal Creek. Lesser deposits occur at Harrison Gold (Abo) and Doctor's Point. These
mesothermal Au polymetallic vein deposits are intimately associated with 25-Ma quartz diorite intrusions, and either consist of
veins in hornfels adjacent to the stiock, as at Doctor's Point, or as vein stockworks within the quartz diorite pluton, as at Hamson
Gold (Ray, 1991). The veins contain quartz, pyrrhotite, and pyrite, and minor chalcopyrite, molybdenite, scheelite, and rare
bismuth telluride minerals (Dawson and others, 199 1). Also occurring in the metallogenic belt are Au polymetallic vein deposits at
Boundary Red Mountain and Lone Jack mines which are located along the western part of the Chilliwack Batholith in Washington
(Ray, 1986).
Clear Creek (Gem) Porphyry Mo Deposit
The Clear Creek (Gem) porphyry Mo deposit consists of an arcuate zone of molybdenite with minor pyrite and sphalerite
which occur in quartz and calcite veins and as fracture filling (EMR Canada, 1989; MINFLLE, 2002). Estimated reserves are 15-9
million tonnes grading 0.07% Mo (MINFILE, 2002). The deposit occurs in an arcuate zone around the northeast margin of an
Oligocene quartz monzonite stock, named the Gem Stock, with a K-Ar isotopic age of 35 Ma. The stock intrudes quartz diorite
and granodiorite of the mid-Cretaceous Spuzmm pluton, and schist and gneiss of the Cretaceous Settler Schist.
Owl Creek Porphyry Cu-Mo District
The Owl Creek porphyry Cu-Mo district consists of veins and disseminations of chalcopyrite, molybdenite, and pyrite
with minor bornite which occur as blebs, disseminations and hcture fillings (Mahoney, 1977; EMR Canada, 1989; MINFILE,
2002). Estimated resources are 10 to 20 million tonnes grading 0.3 to 0.4% Cu and 0.03% MoSz (MINFILE, 2002).The deposit is
hosted in probable mid-Tertiary quartz diorite and feldspar porphyry of the Coast Plutonic Complex, and in propylitic- and
argillic-altered and volcanic rocks of the Late Triassic Cadwallader Group (Mahoney, 1977).
Salal Creek Porphyry Mo Deposit
The Salal Creek porphyry Mo deposit occurs along the contact between a fine-grained granite core and a medium-grained
granodiorite margin of a pluton dated which has a K-Ar isotopic age of 8 Ma (Stephens, 1972). The deposit exhibits in a typical
ring or circular pattern. To the north is the Franklin Glacier porphyry Cu-Mo prospect which has a K-Ar isotopic age of 7 Ma
(Dawson and others, 199 1).