APPLICATION OF REGIONAL QUATERNARY MAPPING TO MINERAL EXPLORATION, NORTHEASTERN NEWFOUNDLAND, CANADA

Mineral exploration on the Baie Verte and Springdale peninsulas of northeastern Newfoundland, Canada, has been hindered by inadequate knowledge of the nature, extent and thickness of the Quaternary cover of glacial drift and of the history of the ice flow. A three-year regional mapping programme that included analyses of the clast lithology, clast fabrics and geochemistry of the matrix of glacial diamictons, together with the measurement of numerous striations, has provided a model of the history of ice movement in the area. This history is complex. It can be explained in terms of a deglacial sequence from the glacial maximum, when ice from central Newfoundland coalesced with ice from the Long Range Mountains. The subsequent retreat of the Long Range Mountains ice cap resulted in an unrestricted radial flow of the central Newfoundland ice. Further retreat led to the development of a remnant ice cap on the southern Baie Verte Peninsula. Clast lithology and the nickel and chromium geochemistry of diamictons are used to demonstrate the glacial dispersal of ultramafic rocks in the southern part of the Baie Verte Peninsula. Dispersal is dominated by the last, eastward ice flow, but the effect of topography on glacial flow conditions has resulted in a rapid decline in nickel and chromium levels directly down ice of the outcrop of ultramafic rocks and a relative increase in these elements further down ice in the lee of topographic highs. Clast fabric analysis is used to supplement the mapping of striations. The use of appropriate statistical criteria in conjunction with an understanding of the genesis of diamictons allows the direction of ice flow to be deduced from strong, unimodal clast fabrics. This is useful in areas of complex ice flow as the flow that prevailed at the time of deposition of a diamicton that is being sampled can be identified.