Glacial geology and prospecting

During the last glaciation of the Superior Quaternary (18000-5000 years BC), the glaciers occupied a superficy up to 44 400 000 square km, including the Laurentain Inlandsis (13 400 000 square km) that then covered the province of Québec and part of Ontario. The amplitude of this geological event considerably shaped the Quebec physiography by the erosion of its rock basement resulting from the displacements of the glacial domes and by the subsequent sedimentary deposit associated with this process.

Under such environment, it is logical that the mining industry applies exploration technics that outlines geochemical or mineralogical anomalies associated to the subglacial sediments and permit the tracing of dispersal trains associated to glaciers movements (advances and regressions); specially in the regions that are more proximal to the glacial centres (i.e. characterized by simpler and shorter displacements).

In this later situation, the mining industry frequently uses a regional reconaissance approach where it collected glacial (fluvioglacial) sediment samples (20-40kg) with a plurikilometric mesh. At this phase, sampling is mainly apply to regional eskers (river channels at the glacier sole) or to remobilized beach sands. The samples are sent to the laboratory where they are screened, and their different fractions are separated. The heavier fractions are isolated and examined with a binocular for the differents minerals. In precious and base metals exploration, the fine fractions are also analyzed for different metals in laboratory. For the the diamond exploration, the possible kimberlite indicator minerals are picked and analyzed with a micro-probe.

If there`s a positive identification of the right minerals or metals, sampling follow-ups with a tighter mesh are done up-ice of the detected anomalies. This new sampling will collected glacial material with shorter transport (i.e. till (and specially basal till), a non-sorted glacial sediment). In these follow-ups, glacial floats prospecting and rock outcrops mapping will also be carried up-ice of the anomalies.