Bulletin 34:
Geology of the Yanks Peak-Roundtop Mountain Area, Cariboo
District, British Columbia
By S.S. Holland, 1954
|
|
View
Entire Bulletin (PDF, 5.87MB) |
| Maps
(43.2MB) |
|
|
Bulletin 34 discusses the geology of the Yanks Peak-Roundtop Mountain area, Cariboo District, British Columbia.
Characteristic features are:
1. The Yanks Peak-Roundtop Mountain area lies at the head of several well-known placer creeks and contains numerous
gold-bearing quartz veins.
2. The recorded gold production of the immediately surrounding district is 69,237 ounces of crude placer gold and 5,204 fine
ounces of lode gold.
3. The area is underlain by a succession of schistose sedimentary rocks of late Precambrian and (or) Cambrian age known as the
Cariboo group.
4. Formerly the Cariboo group was subdivided into the Richfield, Barkerville, and Pleasant Valley formations. These formational
names have been abandoned, and the rocks of the Cariboo group now are divided into the Cunningham limestone, Yankee Belle,
Yanks Peak quartzite, Midas, and Snowshoe formations.
5. The few intrusive rocks are dykes of diabase, diorite, rhyolite porphyry, and lamprophyre.
6. The rocks of the area are involved in a major syncline flanked by two overturned anticlines and in detail are intricately folded.
The
original structural interpretation of Bowman and Uglow of a broad, simple anticlinorium involving huge thicknesses of rock must be
abandoned.
7. The rocks are cut by northerly and northeasterly striking normal faults.
Some faults have a lateral displacement of 800 feet, and
in most instances the eastern block has dropped downward.
8. The area contains several centres of gold mineralization.
9. The localization of veins is dominantly the result of structural rather than stratigraphic factors.
10 .The numerous quartz veins are grouped according to their strike into: -
(a) Northerly striking veins occupying faults or shears.
(b) Northeasterly striking veins occupying tension fractures that may have formed originally as extension joints but which were
reopened subsequently by tensional forces resulting from movement along the northerly faults.
(c) Easterly striking veins occupying shear fractures related to the northerly striking faults.
11. Most quartz veins are associated in one way or another with northerly striking faults; either they occupy the fault, or they occupy
northeasterly or easterly striking fractures that are related to it.
The three vein directions represent fracture directions that are
genetically related, being two complementary directions of shear and the associated direction of tension.
12. The quartz mineralization of the three vein directions was essentially contemporaneous.
13. Ankerite is a common gangue mineral of the quartz veins.
Sulphide mineralization is generally sparse and consists of pyrite,
galena, and sphalerite.
Scheelite, arsenopyrite, and tetrahedrite have been found.
14. Gold is associated with pyrite, and in outcrops becomes visible when the pyrite has been leached.
15. The gold mineralization is considered to be post-Jurassic in age.
16. The most productive placers were on Keithley, Little Snowshoe, Cunningham, and Harvey Creeks just beyond the limits of the area.
17. The erosion of veins within the area is thought to have contributed placer gold to local accumulations, but the chief placer stretches
derived their gold from bedrock sources outside the area and closer to the placers.
18. In recent years several new mineral discoveries have been made, but future lode prospecting must be largely devoted to the finding of
veins that are covered with overburden. The association of gold-bearing veins with northerly striking faults should provide a basis for
close prospecting.
19. It is unlikely that placer prospecting will result in the finding of placer deposits better than small unworked remnants suitable for
individual sniping or small-scale operation. |
Last updated
June 05, 2007 |
