|
RGS Anomalies Identified West of Dease Lake
New government regional geochemical survey (RGS) data for the previously unsampled Dease Lake map sheet (104J) was released on July 5th, 2001. Stream sediment samples were analysed for more than 40 elements, including precious and base metals. The survey results include anomalies characteristic of polymetallic volcanogenic massive sulphide, copper-gold porphyry, and intrusive-related gold deposits in areas with no known mineral occurrences. As well, a multi-element anomaly with high tantalum values occurs in an area that has been generally discounted for its mineral values.
New Volcanogenic Massive Sulphide Targets?
A broad zone of coincident zinc, copper and barium anomalies with associated silver, antimony, selenium and cadmium values extends from Killarney Lake to north of Nuthinaw Mountain. Many of the zinc values exceed 145 ppm, and are higher than the 90th percentile for RGS silt samples in the province. These anomalies are found in streams draining rocks of the Cache Creek Terrane, particularly in areas with the mid-Permian French Range Formation. This Formation consists primarily of basaltic volcanic rocks with associated argillite, chert, felsic volcanics and bright red ferruginous cherts.
The French Range Formation volcanic rocks may be relicts of the same intraoceanic arc which gave rise to the Kutcho Creek massive sulphide deposit (Mihalynuk and Cordey, 1997).
Copper Gold Porphyry Potential
There are a number of copper-gold anomalies underlain by rocks of the Stikine Terrane in the southern half of the Dease Lake map area with no associated mineral occurrences. They appear to be related to Triassic granodiorite intrusions and are prime exploration targets for new porphyry deposits given the well known potential of this part of the Cordillera. There are individual and grouped copper-gold anomalies in the Shesley region and Hotailuh Range.
References
Gabrielse, H. (1994): Geology of the Cry Lake (104I) and Dease Lake (104J/E) map areas, north central British Columbia. Geological Survey of Canada, Open File 2779.
Mihalynuk, M. G. and Cordey, F. (1997): Potential for Kutcho Creek volcanogenic massive sulphide mineralization in the northern Cache Creek Terrane: a progress report. B.C. Ministry of Energy and Mines, Geological Fieldwork 1996, pages 157-170. | 
