Petrology of metasomatic rocks of the Manitouwadge greenstone belt, Northern Ontario
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Date
1995
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University of New Brunswick
Abstract
The Manitouwadge greenstone belt is a remnant of Archean supracrustal rocks that have been metamorphosed to upper amphibolite facies (625°C and 3-6Kbar). This belt is composed of metasedimentary and metavolcanic rocks that outline a regional synform. The synform is a host to Cu-Zn mineralization and associated syn-volcanic hydrothermal alteration. The petrological aspects of the Oam-Crd-Grt gneisses and associated lithologies of this belt are described. A complex deformational and metamorphic history has been revealed. These rocks are found to have high concentrations of Fe, Mg, and Al, while being depleted in alkali elements. Trace and rare earth element data suggest that these rocks have felsic to mafic volcanic protoliths. The application of Grt-Bt thermometry has yielded temperatures between 475 and 520°C, which are well below those at peak metamorphic conditions