By Dan Oancea

 

Two interesting technical sessions were delivered on Tuesday morning at the Mineral Exploration Roundup.

 

Large areas of Canada are covered by a thick layer of glacial sediments that mask the underlying geology and filter and mix the very little signals that manage to come to the surface.

 

Geoscience BC’s Quest program tried to tackle the problem of mapping the bedrock in areas covered by large masses of glacial till and lacustrine deposits (Quesnellia Terrane, B.C.). They flew a few geophysical surveys, collected thousands of new lake and stream sediment samples and got down in an Ottawa basement and re-analyzed old drainage sediment pulps. At this point they had a mix of old and new samples collected from different sampling media and that had been analyzed by different labs over a long period of time.

 

The next step involved statistical analysis as to level the various geochemical data. Once the job done they realized that of the 42 elements analyzed only 17 have the same coverage. They needed to interpret the data so they needed to have the same coverage for all 42 elements. The next step involved the use of a ‘neural network’ and more statistical calculations.

 

The result was an inferred bedrock geology map entirely based on their neural network analysis. When superimposed on the known surficial geology map they realized that it blends well.

 

Their success leads to the idea that you have to heavily sample an outcropping area; then build a geochemical model for the known geology. By using the neural network approach you could extrapolate and infer bedrock geology in adjacent till covered areas.

 

The next session dealt with evaluating the mineral potential in areas covered by glacial sediments (Bonaparte Lake, B.C.).

 

They first tried to figure out ice flow direction and because of not being happy with the decades old interpretation they got on the field and studied glacial striations – they were kind enough to inform us that the students did the job. That work resulted in a new ice flow interpretation.

 

We also learnt that they collected small till samples (2-3 kg) for geochemical analyses and large till samples (15-30 kg) for analyses of gold grains and heavy minerals. The speaker noted that large gold grains counts (let’s say over 100) might indicate that the mineral deposit is near in sight.

 

Till pebbles were also studied as to find possible alteration and mineralization and for assessing dispersal distance and direction.

 

Anomalies were contoured not only close to known Minfile occurrences but also in an area north of Kamloops along the Hwy 24. So the speaker invited the audience to go Kamloops, rent a truck and go and check the side of the road and stake the ground because that morning the ground was still open for staking. Check it out by viewing the GSC online version of their open file.