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

of the North American Craton Margin. The major deposits are at Howards Pass and Anniv (table 4) (Nokleberg and others 1997a.
b, 1998). in!
, 0 Staurolite line
Cret#;ears
m1 Pomhm
. .
CambrianandOtdoncran
a --,-&-silicate
Other Features
0 White mica akaUon ema
Quartzose clhembtd sulphies
m-physie
Massive sulphides
Figure 12 Faro sedlmentary-exhalative Zn-Pb-Ag deposit, Anvil metallogenic belt, Canadian Cordillera. Schematic MOgg section.
Adapted f m
Jennings and Jilson (1 986).
Hmvards -8s (XY) Zn- Pb SEDEX Deposit
The Howards Pass (XY) sedimentary exhalative (SEDEX) Zn- Pb deposit (fig. 13) consists of finagmhed, well-bedded
sphalerite and galena with pyrite as stratiform and stratabound massive bodies, up to 50 meters thick and 3 to 4 lun long, which
are interlaminated with carbonaceous, cyclical, limy mudstone and chert of the rift-related Early Silurian "Active Zone" of the
Ordovician to Devonian Road River Group (Yukon Minfile, 1984; Abbott and others, 1986a, b; Abbott and others, 1 H4;
MacIntyre, 1991). The deposit is one of three related Zn-Pb SEDEX deposits which occur in an elongate, 20 km-wide sub-basin in
the eastern Selwyn Basin. The deposits are interpreted as forming at the base of the continental slope, about 10 krn to 20 km
seaward of a carbonate platform margin. Total reserves and resources are estimated at about 500 million tonna grading 5% Zn,
and 2% Pb (Placer Developments Ltd. Annual Report, June 1982).
Anniv (OF) SEDEXZn- Pb Deposit
The Anniv (OP) SEDEX Zn- Pb deposit consists of sphalerite and galena which occur in saucer-shaped stratiform and
stratabound bodies in Early Silurian cyclic, rift-related carbonaceous mudstone and chert of the Ordovician to Silurian Road River
Group (Morganti, 1981; Yukon Minfile, 1984; EMR Canada, 1989; MacIntyre, 1991). The host rocks interpreted as part of a
Cambrian and Devonian passive margin of the North American Craton Margin. The deposit averages 13 m thick (maximum 45 m)
over a 1.5 km strike length.