Chipman Lake

The Chipman Lake intrusion has been suggested to be a circular stock of syenite about 3 km in diameter associated with dykes of syenite and carbonatite (Ferguson, 1971, p. 43). A strong, approximately circular aeromagnetic anomaly of this size does occur, but Sage (1975 and 1985) shows that this is caused by a metamorphosed early Precambrian syenodiorite to diorite stock. Along the southern shore of Chipman Lake dykes of carbonatite, generally less than 1 m thick, are numerous and cause extensive fenitization. Carbonate, which is essentially dolomitic, is also abundant along joints and cracks in the fenites. Spectacular brecciated fenites with secondary amphibole and phlogopite concentrated along block margins is illustrated by Sage (1985, Photo 8). A few probe analyses of carbonate, phlogopite and amphibole, analyses of carbonatite and fenite and a geological map will be found in Sage (1985).