The identification of mineralized granitoid plutons from ore-element distribution patterns in regional lake sediment geochemical data

CIM Bulletin, Vol. 75, No. 840, 1982

P.M. DAVENPORT, Newfoundland Department of Mines and Energy St. John's, Newfoundland

The ore-element patterns in regional lake sediment geochemical survey data from four areas of Newfoundland containing granite-related mineralization reveal characteristics which can be used to identify mineralized granitoids. The St. Lawrence Granite with its fluorite deposits, the Ackley Granite with molybdenite mineralization, the Grey River tungsten lodes and the newly discovered Mo-W mineralization at Granite Lake, Central Newfoundland, have all been included in the regional lake sediment geochemical surveys, which now cover about 90,000 km2 of the Island of Newfoundland. The lake sediments over these mineralized granites show diagnostically high values of Mo, F, Pb, Zn and, in three of the four cases, U, together with locally high Ag and Cu values. Furthermore, these ore-metals display a distinctive zoning pattern about the intrusives, which can be related to the classical ore-metal zoning patterns developed about many types of mineralized granitoids.

Keywords: Mineral exploration, Geochemistry, Granitoid plutons, Lake-sediment surveys, St. Lawrence Granite, Ackley Granite, Grey River, Granite Lake, Fluorite, Molybdenite, Tungsten, Mineralization.