The Anatomy of an Archean Greenstone Belt

CIM Bulletin, 1965

W. H. Gross Department of Geological Sciences, University of Toronto, Toronto, Ont; S. A. Ferguson Ontario Department of Mines, Toronto, Ont.

The Red Lake greenstone belt is an irregular mass of lavas, sedimentary rocks and intrusives which is approximately 35 miles long, 18 miles wide and 4.7 miles deep. Basaltic volcanics are the oldest rocks within the belt. They are believed to have been laid down on an ancient crust which is at least 3 billion (3 x 109) years old and was composed partly of sediments. The basaltic rocks are overlain by acid volcanics and sedimentary rocks which have been complexly folded and are preserved as a down-folded remnant of younger rocks within the older crust. The volcanics and sedimentary rocks of the greenstone belt have been eut by intrusives with a wide range of composition. The emplacement of the intrusives and the accompanying regional metamorphism which terminated the orogenic activity in this area are believed to have occurred approximately 2.4 billion years ago.
Keywords: Acid, Archean, Archean, Granitic Rocks,, Red Lake Greenstone Belt, Red Lake, Ontario, University of Toronto Press, Gravity, Greenstone belts, Red Lake, Rock, Rocks, sulphur, Volcanic, Volcanics