A brief review of the historic mine production for western Quebec illustrates the significance of the numerous long-lived gold and polymetallic volcanogenic massive sulphide deposits in the region. The 250km-long Cadillac-Larder Lake Deformation Zone, (alternately referred to as the 'Malartic - Larder Lake Deformation Zone' and Cadillac Tectonic Zone), extends from Kirkland Lake, Ontario to well east of Val d'Or, Quebec. This structure has yielded numerous major gold discoveries since the 1920's, including several large new deposits in recent years. The Kirkland Lake area mines (including Kerr Addison) produced an aggregate of 37 million oz from the Larder Lake (Ontario) segment of the fault zone. In Quebec, where the structure is generally referred to as the Cadillac Break, deposits situated along the structure, have produced about 36 million oz gold. While many of the historically significant mines are depleted and closed, the Doyon and LaRonde deposits, which currently produce at a combined rate of about 500,000 oz per year, demonstrate the potential this type of gold deposit offers. Most of the 'Break' from Noranda to well east of Val d'Or is now under active exploration. Many of the worked-out mines are being explored at depth and along strike, while prospects abandoned in the distant past are being re-examined. The Ontario segment is also the subject of considerable attention, with the former Kirkland Lake mine complex currently a center of exploration and development.

Typical gold deposits including the Sigma, Lamaque, Camflo and Kiena Mines, tend to be medium-sized and individually produced between one to four million ounces. Large complex deposits found directly in or very near the Break include the Malartic, Kerr Addison, Kirkland Lake and the Doyon - Bousquet - LaRonde Mines, each producing in excess of 7 million oz. With few exceptions, gold deposits are intimately associated with felsic intrusives that mark the centers of late-stage volcanic events. An early geological map of the Canadian-Malartic deposit (See Map) is a good example of gold mineralization in this context.