and uvarovite garnet. As the hanging wall is traversed
away from the contact, a gradual change from com-
petent grey-brown argillite to grey-green voleanic
and altered volcanic flows in the upper portion is
apparent. This evidence of eugeosynclinal deposition
has resulted in good “wall-forming” material.

STRUCTURAL

Detailed structure within the serpentine body can
be considered complex. Numerous seemingly random
joints, shear zones and vein systems occur throughout
the orebody. These seem to be a result of tension
release and cooling during emplacement of the Cassiar
Batholith and the formation of serpentine. Faults and
shear zones can be generalized into two groups. One
group strikes east-west, with dips of +20 degrees from
vertical. This group is characterized by the “70° shear”
at the southern end of the main orebody (Fig. 4). The
other group strikes approximately north-south, with
either a very steep western dip or an eastern dip near
45 degrees. This group is characterized by the “45°
shear”, which runs through the central portion of the
main orebody and acts as the western boundary of
the southern lobe. Faulting has been both pre-ore
and post-ore, as evidenced by abrupt termination of
fibre at the 70° shear and sheared fibre within the
45° shear. Joints and vein systems are considered as
random in dip, although they seem to persist in strike
between 90°and 180°. Some vein systems are also
associated with the 45° shear as noted above. Two
sets of joints and veins are sub-parallel to hanging-
wall joint sets and will be discussed later.

Structures within the footwall argillites are domin-
ated by the West Fault. This major fault strikes
generally southeast, with a steep dip to the northeast.
It occurs as a 50-ft (15.2-m) to 75-ft (22.9-m) wide
zone of crushed argillite and graphitic material. Stud-
ies suggest a reverse fault and a relationship to the
70° shear within the serpentine. Bedding within the
footwall argillite strikes near north-south, with dips
of 30° to 50° to the east. The argillite-serpentine con-
tact generally parellels this bedding, with some rolls
to give a variable dip between 20° and 70°. Care must
be taken with berm-face and haul-road design in this
area. Joint sets are not well developed, but generally
two dominant orientations are evident. One set of
“cross joints” strike northeast, with steep dips to the
northwest and southeast. These may be comparable to
the tension fractures within the serpentine. The other
set of joints essentially parallels the bedding strike,
with steep dips to the west.

Structures within the hanging-wall argillites are
generally simple, with three dominant sets of joints
and related faults. Two joint sets strike slightly north
of east, with steep dips to the north and south; the
north-dipping set is the most continuous. Major faults
throughout the hanging wall parallel, and occur along,
these joint sets; they offset the argillite-serpentine
contact in many places. A third joint set strikes
slightly east of south, with steep dips to the west. The
combination of three joint systems produces wedge
failures that are generally less than one bench height.
These systems sub-parallel two joint sets in the ser-
pentine, as previously discussed. Evidence is therefore
reinforced for much post-implacement fracturing and
movement. Bedding within the hanging-wall argillites
generally strikes 45 degrees, with fairly shallow (25°-
3 40°) dips to the southeast. The strike of the argillite-
a: serpentine contact varies from north to northeast,

— ' with dips slightly steeper than the argillite bedding
FIGURE 3— Photograph of ore face — 5780 Bench. (30°-45°). As the hanging wall is traversed, some

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