PERMAFROST IN THE KNOB LAKE IRON MIMNG REGION

• Main Author: B. G. Thom
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Canada; Knob Lake; The Knob; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.564.7934; http://pubs.aina.ucalgary.ca/cpc/cpc3-9.pdf

This paper presents in outline the programme of exploration used in mapping permafros t in the Knob Lake (Schefferville, P. Q.) mine region, and the techniques used by the I ron Ore Company of Canada (IOCC) to overcome problems of mining in permafrost a r e a s. Pe rmaf ros t in central Labrador-Ungava occurs a s discontinuous bodies of various shapes and s izes within the upland t e r r a i n above approximately 2200 feet in elevation. In most mine a r e a s of tne Knob Lake dis t r ic t, frozen ground is absent. At two locations shown in F igure 1, F e r r i m a n and Timmins, permafrost presents, however, a problem to mining. The active layer (seasonal f reezing and thawing) va r i e s f r o m 5 to 10 feet i n depth, and i f there i s no permafrost below that layer then the groundwater c irculates f reely in aquifers. Par t icu lar ly under exposed windswept r idges, f r e e of t r e e cover, permafros t o r perennially frozen ground can extend to depths of 253 feet. These perma-f r o s t bodies a r e commonly elliptical in cross-section and a r e elongated