Lithoprobe survey may aid in search of diamonds in Manitoba

Diamond hunters in Saskatchewan and Manitoba may soon have a new target area if the latest Lithoprobe survey over the Trans-Hudson Orogenic belt confirms the presence of a new Archean-aged craton.

Seismic data collected in 1991 suggest a third Archean craton may underlie the Superior Craton and the Hearne Craton near the Saskatchewan-Manitoba border. According to Zoli Hajnal, professor of geophysics at the University of Saskatchewan and a Lithoprobe participant, if this new microcontintent is thick enough, it may have a high potential for hosting diamondiferous kimberlites.

To evaluate this area further, Lithoprobe completed what is believed to be the largest detailed seismic refraction program ever undertaken. The survey, consisting of three profiles, was carried out in northern Manitoba and Saskatchewan under the auspices of the Trans-Hudson Orogen Transect (THOT) project.

The Trans-Hudson Orogen is a major collisional belt which formed when the Archean-aged Superior continent (rocks mainly east of the

Saskatchewan-Manitoba border) collided with another major land mass called the Hearne Craton (rocks extending west-northwest from the northwest corner of Saskatchewan). The crashing of the two cratons sandwiched together several layers of rocks which occupy a 400-km wide region termed the Reindeer zone. It extends from South Dakota northward through the Saskatchewan-Manitoba shield and across Hudson Bay to Cape Smith, Que.

In Manitoba, an east-west survey line was carried out in the Jenepeg-Snow Lake-Flin Flon district, while a north-south transect covered the Lynn Lake-Kenville region. In Saskatchewan, transects were run over the western portion of the Reindeer internal zone and rocks of the Hanson Lake and Glennie Domains.

In several Manitoba mining regions such as Thompson, Flin-Flon and Snow Lake, programs were also carried out to “image” the upper 3-5 km of the crust. Information from the surveys will also be used to trace contacts between major rock units, locate important fault and shear zones at depth, and delineate areas with the potential for hosting ore deposits. Lithoprobe is an integrated geoscience research program, sponsored by the Geological Survey of Canada, the mining industry, universities, and provincial geological surveys. It uses geophysical sounding techniques (seismic surveys), coupled with geological studies of the rocks exposed at surface, to create a profile the Earth’s crust to depths of up to 100 km and in various tectonic settings.