Although the occurrence of diamonds in glacial drift in southern Ontario is well documented, few people are aware that kimberlite dykes have been recognized in two localities just north of Lake Ontario.
One of the dykes, discovered by C.G. Winder, is exposed in a limestone quarry 4 km north of the town of Picton, Ont., 25 km southeast of Belleville, Ont.
The dyke ranges from 0.2 to 0.7 metres wide and trends at 105 with a dip ranging from vertical to 77 south. The dyke occurs along a vertical joint plane in Trenton formation limestones.
The second dyke occurs near Varty Lake, about 30 km northwest of Kingston, Ont. It is intermittently exposed over a distance of 150 metres in five prospect pits near the northwest corner of the lake.
In the most complete exposure, the dyke is 1.5 metres wide, strikes 120 and dips vertically. The limestone host rocks are flat-lying in the area, but beds have been tilted up about 15 on either side of the dyke. These kimberlites are the first post-Paleozoic-aged igneous rocks reported from the stable carbonate platform of southern Ontario. Age-dating suggests that they are Jurassic in age (about 170 million years old). It is believed that these dykes are related to major north-northeast trending regional faults in Grenville-aged basement rocks. The association of kimberlites with major regional structures has been noted in several other areas, including Lac de Gras, N.W.T.
There is no information on the diamond potential of these pipes. — From the paper “The Picton and Varty Lake ultramafic dykes: Jurassic magmatism in the St. Lawrence Platform near Belleville, Ontario,” by R.L. Barnett et al., Canadian Journal of Earth Science, Vol. 21.
Hello
I have a cabin at Varty Lake and found another Kimberlite dyke while digging. The dyke seems to follow the fault line on the west side of lake. There appears to be
Found a large vein with yellow and blue diamonds, keep going back to build my fortune.