Volcanism and Gold Deposition in the Birch-Uchi Lakes Area
A. M. Goodwin Geologist, Ontario Dept. of Mines, Toronto, Ont.
Detailed stratigraphic studies in the Birch-Uchi Lakes area have shown that the volcanic components are arranged in superimposed sequences, or cycles. Each cycle displays a progression from predominantly mafic effusives below to predominantly felsic extrusives above. Sedimentary rocks are preferentially associated with the felsic extrusives. Two volcanic cycles are represented. The average stratigraphic thickness of the volcanic rocks present is 31,000 feet. The original volcanic pile was probably in the order of 40,000 feet thick. The present lithologic composition is estimated to be: mafic volcanic rocks, 60 per cent; felsic volcanic rocks, 27 per cent; sedimentary rocks, 10 per cent; and others, 3 per cent.
Acid, andesitic, dacite, quartz, rhyolite, volcanic, Cycles, Gold, Rock, Rocks, Volcanic, Volcanic rocks, Volcanics