Leahy defends potential of Kirkland Lake area

Ontario prospectors found themselves defending the Kirkland Lake diamond play against an onslaught of negative commentary at a recent short course presented by the Prospectors and Developers Association of Canada.

Kirkland Lake prospector Michael Leahy rose to the microphone on two occasions to refute papers that, directly or indirectly, downplayed the potential for economic diamond discoveries in northeastern Ontario. His defense evoked applause from many in the 400-strong audience. Geologist Howard Coopersmith, the second speaker to address the course in diamond exploration and evaluation, caused a stir when he argued that a diamond deposit cannot be acquired but must be found.

“Once a pipe is located, no new geologic theory or interpretation, different drill hole locations or techniques will find the diamond orebody another has missed,” said Coopersmith, former vice-president of exploration for Ashton Mining and now president of Diamond Mining. “What you see is what you get.” Many of the projects near Kirkland Lake are focused on kimberlite pipes previously explored by Lac Minerals (TSE) and Monopros.

Queen’s University Professor Herbert Helmstaedt added salt to the wound by declaring the structures in the area to be “mantle root destructive.” Where these structures — including mantle plumes, rifts and collision zones — are prevalent, diamonds are unlikely to be preserved in significant quantities.

Based on data gathered on G-10 (calcium-poor, chrome-rich) garnets and chromites, Helmstaedt said the mantle root signature is “barely visible” in the area. His theories are supported by Daniel Schulze, assistant professor at the University of Toronto, who spent 17 years studying kimberlite and mantle xenoliths.

At least 19 kimberlites have been found near Kirkland Lake to date, of which nine have been found to be diamond-bearing. The advantages to exploring in the region include established infrastructure and access to results of provincial and federal geophysical and geochemical surveys.