Heavy minerals and sedimentological studies on the glaciogenic Late Precambrian Gaskiers Formation of Newfoundland

Abstract

The heavy minerals found in diamictites and intrastratal sandstone and siltstone rhythmites of the Late Precambrian Gaskiers Formation of Newfoundland are dominated by altered pyroxenes and amphiboles with lesser amounts of garnet and zircon and trace amounts of tourmaline and rutile. The garnets are angular, fresh in appearance, and about 9% of the garnets have glacially derived chattermark trails. This observation, along with the presence of striated and facetted clasts, suggest that at some time prior to final deposition, the diamictites underwent transport in glaciers which were of ice cap or ice sheet dimensions.