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

Britannia Metallogenic Belt of
Kuroko Cu-Zn Massive Sulfide Deposits,
Southern British Columbia (Belt BR)
The Britannia metallogenic belt of kuroko Cu-Zn massive sulfide deposits is hosted in the Late Jurassic to Early
Cretaceous Gravina-Nutzotin-Gambier volcanic-plutonic-sedimentary belt which forms an overlap assemblage on the inward
margin of Wrangellia superterrane (fig. 63; tables 3,4) (Nokleberg and others. 1997b, 1998, 2000). The significant deposit is at
Britannia. The metallogenic belt also includes the Maggie, Northair, and Nifty deposits.
Britannia Kuroko Volcanogenic Cu-Zn
Massive Sulfide Deposit
The Britannia deposit consists of a series of kuroko Cu-Zn (Ag-Au) ore bodies hosted a roof pendant of dacite tuff and
breccia. The massive sulfi de bodies consists of massive pyrite, chalcopyrite, sphalerite with minor galena, tennantite, tetrahedrite,
barite and fluorite which occur in numerous discrete, concentrically zoned siliceous ore bodies (EMR Canada, 1989; Dawson and
others, 199 1 ; MINFILE, 2002). A U-Pb zircon age for a feldspar porphyry dike which cuts the deposit indicates a Middle Jurassic
or older age for the deposit (Ray and Webster, 1994). The host rocks are metamorphosed dacite to andesite pyroclastic rocks. The
massive sulfides consist mainly of stringers which occur in the upper of two major mafic to felsic metavolcanic layers which are
separated by, and overlain by metasedimentary rock. From 1905 to 1974, the mine at the deposit produced 47,884,558 tonnes of
ore from which 15.3 tonnes Au, 180.8 tonnes Ag, 5 17 tonnes Cu, 15.6 tonnes Pb and 125.3 tonnes Zn were recovered. The nearby
Northair deposits near Whistler are interpreted as volcanogenic massive sulfide deposits remobilized during emplacement of
adjacent plutons (Miller and Sinclair, 1985). The Early Cretaceous metavolcanic host rocks form pendants and screens within
granodiorite of the Coast Plutonic Complex. The deposit and host rocks are thinned and partially remobilized by the northwest-
trending Britannia shear zone (Payne and others, 1980).
Origin of and Tectonic Controls for
Britannia Metallogenic Belt.
The Britannia metallogenic belt is hosted in the Middle and Late Jurassic and Early Creraceous sedimentary and calcalkaline
volcanic rock of the Gambier Group which is intruded by partly coeval plutons which range in age from 130 to 94 Ma
(Nokleberg and others, 1994c, 1997~; Monger and Nokleberg, 1966). The arc-related calc-alkaline volcanic and sedimentary rocks of
the Gambier Group overlie Jurassic and older plutonic, volcanic and sedimentary rocks of the Coast Plutonic Complex and Harrison
terrane on the east, and Middle to Late Jurassic plutons of Wrangellia Superterrane on the west. The Gambier Group and coeval
plutonic rocks are part of the extensive Gravina-Nutzotin-Gambier volcanic-plutonic-sedimentary belt which forms a major middle
Mesozoic sequence of volcanic. sedimentary, and plutonic rocks deposited on and intruded into the Wrangellia superterrane. The belt is
interpreted as an elongate island arc which extended for several thousand km along the inner margin of the Wrangellia superterrane (sheet
3; Nokleberg and others, 1994c, 1997~). This Middle Jurassic to Early Cretaceous island arc, which was built on the Wrangellia
superterrane, is interpreted as forming immediately before accretion of a of the superterrane to the accretionary margin of the North
American Cordillera in the mid-Cretaceous (Monger and others, 1994; Monger and Nokleberg, 1996; Nokleberg and others,
2000). The volcanic exhalative activity deposited Kuroko-type massive sulfides in several centers in the Gambier Group. Mineral
deposits and their host rocks were sheared and attenuated along faults active during and after the accretion of the Wrangellia
superterrane.
Late Early Cretaceous
Metallogenic Belts (120 to 100 Ma;
Figures 61, 62)
Overview
The major Late Early Cretaceous metallogenic belts in the Russian Far East, Alaska, and the Canadian Cordillera are
summarized in table 3 and portrayed on figures 61 and 62. Six major belts are identified. (I) In the Russian Southeast, the
Badzhal-Ezop-Khingan (BZ-KH) belt of granitic-magmatism-related deposits, which is hosted in the Khingan-Okhotsk volcanic-
plutonic belt, is interpreted as forming in the Khingan continental-margin arc. (2) In the Russian Southeast, continuing on fnn the
Early Creteacoues was the Sarnarka (SA) belt of granitic-magmatism-related deposits. (3) In the Russian Northeast, continuing on
from the Early Cretaceous, was the Kular (KU) metallogenic belt which contains Au quartz vein, and granitic-magmatism-related
deposits. (4) Also in the Russian Northeast, was the Anadyr River (AD) metallogenic belt of Au quartz vein deposits, which is
hosted in the Mainitskiy, West Pekulney, and (or) Penzhina-Anadyr terranes. The belt is interpreted as forming during regional
metamorphism and generation of hydrothermal fluids associated with accretion and collision of Mainitskiy island arc onto North
Asian Craton margin. (5) In Northern Alaska, the Nome (NO) and Southern Brooks Range (SBR) belts, which contain Au quartz
vein deposits, are hosted in metamorphosed continental-margin terranes and are interpreted as forming during regional