ted
-(=

Kwanika Creck overlies the quartz diorite outcropping along the
ereek, The age of this conglomerate is probably Cretaceous or
younger. “

Colearcous Tufa

On the point on the south shore of the west arm of
Tchentlo Lake calcareous tufa has been and still is being depositod
by warm springs issuing from Permian limestone. The deposit is at
least 100 feet in diameter and has a maximum thickness of about
25 fect. The tufa is a very porous, white rock composed of travertine.

STRUCTURAL GEOLOGY
Faulting

A major fault zone, here called the Pinchi fault zone,
has been traced from south of the east end of Pinchi Lake 90 miles
northwest to Kwanika Creek. It is the main structural feature of the
mereury belt, and the area mapped consists of the strip of country
traversed by the fault zone and extending a few miles either side of
it. The fault zone forms the contact between stratified Permian
rocks on the southwest and predominantly Mesozoic rocks on the north-
east. It was observed at the following localitios: on the south shore
of Pinchi Lake 3 miles from the east end; in the vicinity of the
Pinchi Lake mercury mine; on the south side of Pinchi Mountain; at
the west end of Tezzeron Lake; east of Takatoot Lake; cast of Indata
Lake; and along Kwanika Creek. In all these localities the fault zone
is chgracterized by carbonatization of the wall-rocks. In the vicinity
of the Pinchi Lake mercury mine, east of Indata Lake, and along Kwanika
Creek the zone of faulting is about 800 feet wide and includes two or
more approximately parallel faults. Along these faults the carbonatized
rocks are breeciated and silicified across widths of a few inches to
30 feet, and are bounded by slickensided slipwall surfaces dipping 45
to 70 degrees southwest. The faults at the *Pinchi Lake mercury mine
and ‘along Kwanika Creek are of the reverse type. There has undoubtedly
been more than one period of movement along these faults and the final
result is that along the major Pinchi fault zone the Permian block to
the southwest has moved up with respect to the Mesozoic block on the

northeast. Numerous branch faults were observed near the Pinchi Lake

mercury mine and on the south slope of Pinchi Mountain...

East of Indata Lake the geology is rather ae and
until further field work is done the interpretation given must be
regarded as only tentative. A sale ec trending ridge of Permian
limestone outcrops approximately 3 = Mile east of the Pinchi fault zone.
Mesozoic rocks outcrop east of this limestone ridge and also occupy the
area between the ridge and the fault zone. The contact with the Mesozoic
rocks on the west side of the limestone ridge is along a draw and on
the east side is at the base of a steep cliff. These contacts are
believed to be fault contacts and the faults are ERI branch faults
from the Pinchi fault ZONG «

' Folding

The Permian strata on the southwest side of the Pinchi
fault zone strike northwesterly at a slight angle to the fault zone and
are closely folded into a series of long anticlines and synclines. North
of Trembleur Lake two major anticlines separated by a major syncline