The petrology and geochemistry of the minor intrusions in the central metasedimentary belt, Grenville Province, southern Ontario, Canada

The study area lies within the western section of the Elzevir terrane, in the Central Metasedimentary Belt. A supracrustal sequence of carbonates and clastic metasediments, interdigitating with metavolcanics occur in this area, intruded by a series of dykes. The majority of minor intrusions are mafic in composition; a minor number of felsic samples have been identified. The dykes have been metamorphosed to middle and upper amphibolite facies of low-pressure type, transitional into moderate pressures. Major and trace element contents were determined by X-Ray Fluorescence Analysis. Four distinct geochemical suites have been recognized: a Low Zirconium Suite of tholeiitic basalts, an Intermediate Zirconium Suite of tholeiitic basalts, andesites, dacites and rhyodacites, a Calc-Alkaline Suite of basalts, andesites and rhyolites, and a Highly Fractionated Tholeiite Suite consisting of a single, unevolved tholeiitic basalt. The geochemical suites were modelled from three distinct sources; two spinel lherzolites and a garnet lherzolite, by partial melting and fractional crystallization. The dykes are interpreted as feeders to presently or formerly existing metavolcanic sequences; the Intermediate Zirconium Suite has been successfully correlated with the Tudor volcanics. Geochemical evidence indicates that the minor intrusions were emplaced in a back-arc basin environment, on continental crust of variable thickness. (Abstract shortened by UMI.)Dept. of Geology and Geological Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1990 .K455. Source: Masters Abstracts International, Volume: 30-03, page: 0678. Thesis (M.Sc.)--University of Windsor (Canada), 1990.