La Scie Complex
The La Scie intrusive complex comprises the Reddits Cove gabbro, the La Scie granite and the Seal Island Bight syenite, only the last being peralkaline.
Canadian occurrences of alkaline rocks have previously been listed and described in some detail in the monograph by Currie (1976a), although a significant number that have come to light since that publication will be found here. These new localities notably include extensive areas of peralkaline granites in Newfoundland, and of alkaline volcanics and intrusives in British Columbia, and it seems likely that many future discoveries will be concentrated in the latter area.
Many of the more northerly carbonatite occurrences are only poorly known and have not been dated. Although generally badly exposed, many have been drilled but rarely have findings been published. Many Canadian occurrences have been investigated for their economic potential (see, for instance, Ferguson, 1971) and important mining operations for nepheline syenite at Blue Mountain and Nb at St-Honore are taking place, with active exploration and appraisal for phosphate and vermiculite elsewhere. A number of occurrences in Ontario is described by Parsons (1961) and nearly 30 Ontario carbonatites have recently been re-investigated by R.P. Sage, although his internal reports were not available when the present accounts were compiled. K-Ar ages on numerous carbonatites in eastern Canada are given by Gittins et al.(1967) and of a broader range of alkaline rocks by Doig and Barton (1968). Rb-Sr ages and Sr isotopic ratios for many Ontario occurrences have been published by Bell et al. (1982).
The La Scie intrusive complex comprises the Reddits Cove gabbro, the La Scie granite and the Seal Island Bight syenite, only the last being peralkaline.
The Deloro Stock intrudes sediments and volcanics of the Grenville and Hastings Groups within the Grenville Structural Province near its southern boundary with overlying Palaeozoic sediments, which partly cover it.
On Sullivan Island and nearby smaller islands in the Ottawa River, and on the adjacent west bank of the river, a complex of carbonatites and fenites is exposed.
A regionally metamorphosed complex of agpaitic nepheline-bearing rocks is poorly exposed along the eastern shore and hills beside Sheffield Lake.
Dykes of possible nephelinitic affinities occur over a wide area of Quebec approximately between Mattawa and Bachelor Lake. The dykes are up to 60 cm thick and have been described principally from drill core.
A small crescentic mass of nepheline syenite outcrops 1 km south of Nadon Bay on the southern side of Cabonga Reservoir.
Currie (1976a, p. 201) reports nepheline-bearing rocks from the edges of the Baskatong Reservoir syenite. This intrusion is briefly described by Corriveau (1985, p. 171) but she makes no reference to nepheline-bearing rocks.
The Kensington complex covers about 40 km2 and comprises five distinct phases of syenite, monzonite, diorite and pyroxenite, the distribution of which are shown by Corriveau (1985, Fig. 22.2) who also gives petrographic details. These rocks are not peralkaline, but Currie (1976a, p.
An approximately circular intrusion 8 km in diameter, Ste-Veronique intrudes migmatites, schists and gneisses of the Grenville Province.
Lac Rouge is an approximately circular body of 25 km2 forming a depression corresponding to a positive aeromagnetic anomaly. It is poorly exposed. Nepheline-bearing rocks occur in a north- south trending ridge about 1.6 km in length by 250-300 m wide.