Age of BC ‘blondes’ clarified

I read with interest the commentary by David Lefebure regarding platinum group element potential in British Columbia (T.N.M., Nov. 12-18/01) and would like to comment on one item.

In describing the copper-PGE occurrences in southern British Columbia, Dr. Lefebure unfortunately perpetuates a long-held misconception regarding the age of the intrusive rocks hosting at least some of these bodies. I refer to the case of the Maple Leaf and other “platinum blonde” occurrences in the Franklin camp, north of Grand Forks, B.C. Although the intrusive rocks have indeed been “correlated with the Eocene Coryell intrusions,” they were shown by Myra Keep and J.K. Russell to be Jurassic, based on a potassium-argon age determination of 150, plus or minus 5 million years. This information appears in an article published in a 1992 issue of Canadian Journal of Earth Sciences.

Giles Peatfield

Vancouver, B.C.