Schaft Creek is a calc-alkalic porphyry copper-goldmolybdenum

deposit formed near the eastern contact of

the Hickman granodiorite batholith with Stuhini Group

mafic volcanic rocks. The Galore Creek deposit is

developed in alkalic rocks near the western margin of the

Hickman batholith. Schaft Creek mineralization is dated

at 222 Ma, nearly identical to the age of the batholith.

Although not an alkalic porphyry deposit, Schaft Creek is

similar to Galore Creek in that the deposit occurs in a

unique part of a sub-horizontal volcanic sequence

consisting of tuff, breccias and epiclastic rocks. The

principal Liard zone is fault-bounded by a steep structure

to the east and by a 45º east-dipping structure to the west.

Recent drilling has linked the Liard and northerly

Paramount zones so they are considered now to be a

single zone. Thought to represent deeper portions of the

porphyry, the Paramount zone is characterized by

extensive igneous brecciation of a feldspar porphyry

intrusion, primary igneous zoned sulphides and a higher

abundance of chalcopyrite and molybdenite. The West

Breccia zone lies further west, associated with a subvertical

fault. The West Breccia zone is 30 to 200 m wide,

extends more than 1000 m and consists of angular

hematized fragments in a matrix of quartz, tourmaline,

chlorite, specularite and sulphide minerals. The Liard

zone comprises a sub-horizontal quartz vein stockwork

that is developed in volcanic rocks and less abundant

granodiorite dikes; this vein orientation accounts for the

flat copper grade contours that characterize the deposit.

Potassium feldspar alteration is pervasive in intrusive

rocks and less intense in volcanic rocks where it is

restricted to vein envelopes. Veins in the Liard zone are

broken and disrupted on a small scale; veins commonly

do not extend 10 cm without being segmented by faultfractures.

Copper mineralization is contained in

chalcopyrite and bornite as stockworks, disseminations

and in breccias. Molybdenite occurs as disseminated blebs

and stringers in stockworks and veins.