Geochemistry of the Cambrian manganese deposits of eastern Newfoundland

Abstract

Manganese-rich sedimentary rocks are exposed intermittently throughout an area of 40,000 km² in the Avalon Zone in southeastern Newfoundland. Paleontological data indicate that the manganese-rich rocks form a stratiform deposit of basal Middle Cambrian age and that the manganese horizon is related to a disconformity whose duration increases from south to north. Stratigraphic measurements and chemical analyses show that the manganese horizon becomes thinner (from 25 to 1 m) and progressively enriched in Mn relative to Fe (Mn/Fe from