Boos

Granitic and Related Intrusives

The intrusive rocks in the larger bodics are mainly
“granodiorite, rarely diorite and granite; smaller bodics may be
similar or are porphyrics (granodiorite, quartz, feldspar, etc.)
and rhyolites of similar composition. Most are light coloured
and readily recognizable cxcept where altered by mineralizing
solutions. The porphyries and rhyolites are merely finer
grained phases of the granitic rocks. Many of the granitic
bodies are similar in character and relationships and most of
them may be related and of approximately the same age. They
have been considered by some writers to be Tertiary and by
others to be Mesozoic. One body of mount Nadina south of
Houston has been classed as Tertiary because it cuts Upper

Cretaceous rocks. Since the ore=bodies are considered to be

! henge, A.H.: Owen Lake; Geol. Surv., Canada, Sum. Rept. 1929,

Divie AG repeiOce

related to the granitic intrusives their age is important, as
all rocks younger than the intrusives would be unfavourable for
the occurrence of mineral deposits. In 1934, mineralization
similar to that in many of the deposits on Hudson Bay ‘nzountain
was discovered in the Lake Kathlyn Coal mine in rocks bearing
Skeena formation fossils. One of the veins on the west side of
the mountain also was found to continue into the Skeens forma-
tion. In the same year on Viking hill an extensive deposit of

pyrite was found in sandstone and conglomerate believed to be

of Upper Eocene or Oligocene age owing to the fact that the beds

are close to, have the same strike as, and resemble litholog:-
cally, strata of that age which outcrop on Driftwood creek. In

view of these observations it seems advisable, until the ages

of intrusive bodies and the mineral deposits can be definitely