Bulletin 064

Bulletin 064

BUL 064

Metallic Mineral Occurrences of the Exposed Precambrian Shield in Northeastern Alberta

Author(s) Langenberg, C.W. Eccles, D.R. Date 1996-03-01

The description of 190 metallic mineral occurrences on the exposed Precambrian Shield of northeast Alberta provides models for mineral deposition, establishes exploration targets and gives insights into the economic potential of the mineral showings. Commodities include gold, uranium, base metals and rare earth elements. Among these occurrences, 20 have been investigated sufficiently and are of sufficient exploration importance to be classified as a mineral showing.

The most interesting result is the presence of gold and base metals, which were concentrated by shearing, in metasedimentary belts. Geochemical analyses of grab samples from deeply weathered sulfide horizons in shear zones of the Potts Lake, Waugh Lake, Doze Lake and Pythagoras Lake areas, contain up to 3.2 g/t gold. These results indicate the presence of shear-hosted Precambrian lode gold deposits. It is recommended that industry follow up on these gold showings. The Selwyn Lake area contains copper anomalies, which are associated with a stratiformal, but shear-related sulfide zone. Although no large amount of precious or base metals was found, the concentration of pyrite-pyrrhotite is important.

Quartz-tourmaline veins, which intrude granite and metasediments near Waugh Lake, contain gold, in association with anomalously high arsenic, molybdenum and tungsten contents, and may indicate that potential exists for Precambrian lode gold deposits.

Uranium showings account for nearly half of the mineral occurrences described in this report. The majority of the uranium mineralization is hosted in pegmatite and related granitoids. Their average grades are at present sub- economic. However, the uranium showing located at the West Arm of Andrew Lake has an associated anomalous molybdenum content. Some radioactive sites are associated with anomalously high contents of thorium and rare earth elements. Some iron-rich pegmatitic breccias contain 25 to 29 per cent iron, together with anomalously high vanadium contents.

Langenberg, C.W. and Eccles, D.R. (1996): Metallic mineral occurrences of the exposed Precambrian shield in northeastern Alberta; Alberta Energy, AE/AGS Bulletin 64, 77 p.