qe

such old channels. Only brief visits were made to most of
these properties, and for details of the operations the reader
is referred to previously pubdlished reports~. However, as a

Learn aes TTR EMR RSE a) aM REP Reee
Geol. Surv., Canada, Sum. Rept. 1935, pt. A, pp. 9 to 30;
Ann. Rept., B.C. Minister of Mines, 1936, pt. C, pp. 3 to 16.

Ee ee

result of the study of the bedrock geology and mineral deposits
of the area the writers believe that most of the gold in the
placer deposits along Germansen and Manson Rivers and their
tributaries resulted from the erosion of carbonate-quartz-
mariposite-chlorite rocks, less altered rocks, and quartz veins
along the Manson fault zone and associated branch faults. This
conclusion is based on the following observations: (1) The
placer deposits exhibit a Linear arrangement along the Manson
fault zone in: a belt approximately 25 milés long by 3 miles
wide. Wone of- the deposits is more ‘than 2 miles from an observed
or projected major fault zone, and “all are probably much nearer
minor fault, shear, and fracture zones. (2) Much of the gold in
the. placers is coarse and angular, indicating that it has not
been: transported far. One nugget weighing 24 ounces was recovered
and.many others up to 2 and. 3 cunces. (3) Most of the placer
« deposits: occur on the downstream side of outcrops of carbonate-
quartz-chlorite-mariposite tocks. For example, Discovery Bar
on Manson River, reported to,have been one of the richest deposits
in the area, is directly below a wide carbonate zone. The
- deposits on upper Slate Greek, are, however, exceptional in that
they lie on the upstream side and may owe their: position either
to an unexposed fault zone on Slate Creek above the placers, or
to the poasibility that Slate Creek formerly drained in the
: other direction. into Germansen River.” (4) Assays on specimens
of carbonate~quartz—-chlorite- -mariposite rocks yield a trace to
0.01 ounce of gold a ton. These rocxs Gould be the source of
much of the fine gold.. (5) The most productive ‘placers lie near
. fault zones containing quartz veins with good values in gold.
» {Many of the larger nuggets contain vein quartz with the gold
ycand this quartz appears to be identical with that in the veins.

Lode Deposits

The lode deposits of the map-area may be classified
on a basis of. rock structure ag follows: (1) deposits related

to the Manson: fault zone and subsidiary ‘fault and shear zones;

(2). deposits related to shear (or: fracture ) zones along igneous
Coy eee eC other deposits.

Deposits Related to Manson Favlt Zone. As previously
pointed out the Manson fault zone is marked by a zone of buff-
coloured carbonate-quartz- chlorite-mariposite rocks about 200

feet wide... These carbonate: rocks have been formed by hydrothermal
alteration. of the wall-rocks resulting in’ the replacement of all
the original minerals, except quartz, “by, mainly, ankeritic
carbonate. Similar carbonate rocks occur along some of the
subsidiary ‘fault and shear zones, whereas: EOS others the
alteration was loss complete and’-the wall-rocks have retained
much of their original appearance. Assays on carbonate-quartz-
chlorite- mariposite rocks from sight places along the Manson

fault zone yielded a trace to 0.01 ounce of gold and 0.03 to

0.69 ounce of silver: ton..-None..of these sample s was from

quartz veins, and the only metallic mineral apparent in them

was pyrite in scattered grains. Quartz veins and stringers were
observed at many placcs along the fault zone and in subsidiary
structures. \ In the Garbonate rocks they occur’ commonly as