Regional geochemical mapping for earth science and environmental studies

CIM Bulletin, Vol. 73, No. 817, 1980

J.A.C. FORTESCUE Independent Consultant San Marcos, California, I. THOMSON and R.B. BARLOW, Ontario Geological Survey, Toronto, Ontario

Originally developed for use in mineral exploration, regional geochemical mapping based on stream (and lake) sediment sampling is showing broader application in other areas of the earth sciences and in environmental science. The purpose of this paper is to focus attention on the role of regional geochemical mapping in relation to geological and environmental studies. This is achieved using a descriptive equation for the chemical composition of a stream-sediment sample and then relating it to the use of successive approximations in geochemical and environmental investigations. The procedure is further qualified with reference to time and process in the formation of regional geochemical patterns. Examples are included of studies based on stream sediments related to bedrock geology, surficial geology, ecology and man's effect on the geochemistry of the environment. The range of applications of regional geochemical mapping in earth and environmental studies is outlined and some conclusions drawn regarding the future development of geochemical mapping under Canadian conditions.

Mots Clés: Mineral exploration, Exploration techniques, Geochemical exploration, Environmental control, Stream sediments, Lake sediments, Chromium, Zinc. Molybdenum, Lead, Nickel.