47

there lead and zinc were extracted as well as gold and silver. In Marmot
River district the deposits mined were of the high-grade silver-lead type.
With high prices for silver, lead, and zinc, many of the deposits in these
districts might produce ore at a profit. Even at the present when prices
are low several properties are operated at a profit.

Of special interest is the Portland Canal fissure zone, so named by
McConnell after the Portland Canal mine. The fissure zone is in the
upper argillites of the lower part of the Hazelton group and is character-
ized by shearing, faulting, and the presence of parallel, mineral-bearing
veins. The width of the zone is variable and is as great as 1,500 feet
in some places. The length is upwards of 4 miles. The location of most
of the mine workings and veins in that part of the fissure zone north of
Glacier creek is shown by Figure 1. Only veins wider than 2 feet are
represented and for simplicity some of the smaller mine workings are
omitted.

The fissure zone, at Victoria Mines at its most northerly known point,
lies in the argillites along their contact with overlying volcanics. South-
ward the zone departs gradually from the upper edge of the sediments
and passes through lower members of the sedimentary series. Where the
zone crosses Glacier creek it is still near the overlying volcanics, but is
a few hundred feet from them. South of Glacier creek the zone diverges
from the sedimentary-volcanic contact at a more rapid rate until at its
most southerly known point it is well down in the sediments. The
argillites strike north and dip west at 45 degrees. The strike varies to
northwest or to northeast and the angle of dip varies from about 10
degrees to 80 degrees. Several dykes intrude the argillites.

Prior to the formation of the metalliferous veins the argillites were
folded, sheared, and faulted. Shearing was restricted to the Portland
Canal fissure zone and within it was confined to many narrow, parallel
zones along which considerable differential movement probably took place
so that the narrow shear zones are faults accompanied by shearing. The
narrow shear zones follow rather closely the strike and dip of the argillites
but in many places crosscut the bedding planes at small angles, so that
whereas the argillites strike north the narrow shear zones strike a few
degrees west of north. Less is known about the dip of the shear zones,
but in mine workings their angle of dip in some places is steeper and in
other places less steep than that of the argillites.

Two faults, perhaps formed at the same time as the narrow shear
zones, follow the Portland Canal fissure zone. The faults strike north
with, approximately, the average strike of the argillites, but the faults
are fairly straight and crosscut the argillites at all curves or bends in
the strata. These are common and, therefore, in most places the faults
crosscut the beds. The angle of dip of the faults is in general steeper
than that of the argillites. The narrow shear zones and the faults inter-
sect at an angle generally less than 15 degrees but as great as 45 degrees
in a few places. The angle of dip of the faults is in general steeper than
that of the shear zones. After the faults and shear zones were initiated,
differential movement continued along a few shear zones and along the
faults.

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