Geology and alteration associated with the Hamlin Lake VMS system, Shebandowan Greenstone belt, Northwestern Ontario, Canada

Abstract

The Hamlin Lake area is located approximately 120 km southwest of the City of Thunder Bay, Ontario within the Shebandowan greenstone belt of the Wawa Subprovince, Superior Province. The purpose of this study was to understand the relationship between an extensive felsic volcanic rock package and the hydrothermal alteration. Mapping of the area exposed five major lithologies consisting of mafic metavolcanic rocks, intermediate metavolcanic rocks, felsic metavolcanic rocks, felsic intrusive rocks and iron formation. The felsic metavolcanic rocks vary from rhyolites and banded ash to lapilli tuffs and debris flows, whereas the intermediate metavolcanic rocks are made up of dacites and andesites. The only mafic metavolcanic rocks are the debris flows. The felsic intrusive rocks consist of a quartz-eye porphyry and pink breccia. Primary textures, such as fiamme, can still be observed and which are indicative of a subaqueous environment. Major and trace element geochemical analyses were undertaken on 200 samples of andesitic to rhyolitic volcanic and volcaniclastic rocks.