Geochemical methods for the discovery of blind mineral deposits

CIM Bulletin, Vol. 75, No. 844, 1982

R.W. BOYLE, Geological Survey of Canada Ottawa

Areal (two-dimensional) geochemical surveys, based mainly on secondary dispersion halos and trains in media such as surface waters, soils and drainage sediments, have proven particularly successful in recent years and have greatly assisted in the discovery of a large number of varied mineral deposits. Three-dimensional surveys based on primary halos and leakage halos have received relatively little attention by research organizations and the mineral industry. Such surveys offer many novel approaches for discovering blind mineral deposits deeply buried below overburden or within their host bedrocks.This paper reviews detailed methods for the discovery of blind mineral deposits based on sampling rocks (lithochemical methods), soils and other types of overburden (pedochemical methods), waters (hydrochemical methods), gases (atmochem-ical methods) and biological materials (biogeochemical methods). All are applicable to the discovery of blind deposits; the efficacy of each or in combination depends essentially on the type of mineralization, the extent of the development of the primary and secondary dispersion halos, and the finances available for sampling techniques employing overburden drilling, bedrock drilling, and sophisticated water, gas and vegetation collection.

Keywords: Exploration, Geochemical exploration, Mineral deposits, Blind mineral deposits, Metallogenic provinces, Lithochemical methods, Enveloping halos, Leakage halos, Carbonatites, Pegmatites, Skarn, Hornfels, Vein deposits, Massive sulphides, Carbonate-hosted deposits, Porphyry deposits.