Diamond and Metallic-Mineral Potential of the Peerless Lake Map Area, North-Central Alberta

A regional geochemical sampling program for diamond and metallic-mineral potential was completed during the summer of 1998 in the Peerless Lake map area, north-central Alberta. The area encompasses the 1997 discovery of diamondiferous kimberlites on the flanks of the Buffalo Head Hills by Ashton Mining of Canada Inc. and its co-venture's Alberta Energy Company Ltd. and Pure Gold Minerals Inc. The study is intended to provide reconnaissance-scale information from an area with known diamondiferous kimberlites.

The regional geochemical survey collected 184 samples, targeting a variety of sampling media: 88 stream-sediment heavy-mineral concentrates; 25 glaciofluvial, or sand and gravel samples; and 1 preglacial sand and gravel sample. More than 2000 silicate and oxide grains were recovered and 1500 picked (definite and possible) silicate minerals were plotted, regardless of chemistry, to study their distribution relationships. In total, 606 grains were selected for quantitative analysis of major- and trace-element chemistry using an electron microscope.

The spatial distribution of silicate kimberlite-indicator minerals, particularly peridotitic garnet and olivine, clearly shows four areas with elevated grain counts. Three ''anomalous'' areas occur in the northwestern and north-central parts of the map area, close to known kimberlite clusters. Heavy mineral sampling must therefore, be recognized as a valuable exploration tool in other areas of Alberta that are similarly covered with complex surficial deposits of glacial origin. A fourth anomalous area, located in the southwestern part of the area, is characterized by a wide distribution of elevated grain counts. While glaciofluvial samples contain a large number of indicator minerals, high indicator-mineral grain counts are generally independent of sample media. The distribution patterns of indicator grains in areas of known kimberlite occurrences are generally close to the kimberlite source.