Herman Lake
Emplaced into Archaean greenstones and granites which are strongly sheared near to the contacts, the intrusion is about 8x3 km and consists of nepheline syenites of variable colour index.
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).
Emplaced into Archaean greenstones and granites which are strongly sheared near to the contacts, the intrusion is about 8x3 km and consists of nepheline syenites of variable colour index.
Firesand River is an approximately circular carbonatite complex some 2.4 km in diameter giving a strong aeromagnetic anomaly.
This is an oval complex of 7x5 km, more than half of which is hidden beneath Nemegosenda Lake. It cuts Precambrian gneisses which are intruded by biotite pyroxenite and gabbro.
This small intrusion with no outcrop has a circular magnetic anomaly indicating a probable diameter of 1.5 km. Drilling indicates an ijolitic complex with syenite and carbonatite.
An elongated carbonatite-ijolite complex of 2.7x1 km, extending along and cut by a north-south-trending fault, is emplaced in massive Precambrian granites and diabase dykes. Outcrop is abundant and drilling extensive so that the complex is reasonably well defined.
Alkaline lavas and tuffs occur in the Timiskaming Group of the Abitibi Volcanic Belt, which is perhaps the largest continuous greenstone belt in the world. The Timiskaming Group comprises a sequence of conglomerates, lithic sandstones, greywackes and argillites, andesites and pyroclastic rocks.
An almost circular intrusion nearly 10 km in diameter, the Otto Stock cuts metamorphosed Archaean volcanic and sedimentary rocks, and in the south granodiorites of the Round Lake batholith.
In an area of about 1000x600 m east-northeast of Kusk Lake feldspathic sandstones and greywackes of the Mississagi Formation (Huronian Supergroup) are fenitized.
The Nemag Lake fenite occurrence covers about 800x600 m and lies 5 km northeast of the Kusk Lake occurrence (031-00-078).
Breccia bodies lying southeast of the Sudbury Basin comprise fragments of quartzite and gabbro in a finely comminuted matrix.