TRACE-ELEMENT CHEMISTRY OF VEGETATION APPLIED TO MINERAL EXPLORATION IN EASTERN NOVA-SCOTIA, CANADA

Trace clement analysis of conifer tissues demonstrates the application of biogeochemistry to mineral exploration for gold and other metals h osted by lower Paleozoic metasediments in eastern Nova Scotia. At the regional scale, enrichment of up to 170 ppb Au and 72 ppm As in the as h of twigs from balsam fir (Abies balsamea) coincides with known gold districts and major shear zones. These concentrations are approximatel y 30 times background level. The twig trace element chemistry indicate s previously unsuspected Au potential in Carboniferous Horton Group se dimentary rocks, and around the contact aureoles of Devonian granitoid s where the twigs are also enriched in Cs ( X 30), Sb ( X 3), Rb ( X 3 ) and W ( x 10). Along the Minas Fault, separating the Avalon and Megu ma terranes, anomalous groupings of Ba and Cr in twigs suggest explora tion potential for base metal (Cu-Pb-Zn) and mafic or ultramafic (Co-N i-Pt group element) associations. Detailed biogeochemical studies at f ive till- and/or bog-covered localities near the Beaver Dam gold depos it outline mineralization buried beneath up to 25 m of surficial sedim ent. An association of Au, As and Cs in the vegetation provides consis tent patterns equal to or better than the more erratic geochemical res ponse in soil and till surveys over the same areas. Concentrations of up to 170 ppb Au in the ash of twigs indicate locations suitable for f urther exploration. The low shrubs Labrador tea (Ledum groenlandicum), leather leaf (Chamaedaphne calyculata) and bog laurel (Kalmia polifol ia) were collected from two small boggy areas suspected to overlie gol d-bearing bedrock. Typically, these species contain < 10 ppb Au in ash . At one site they contained 22 to 36 ppb Au, and at the other they yi elded 55 to 85 ppb Au, in association with Cs and weak Co enrichment. In the glaciated terrain of eastern Nova Scotia, biogeochemical explor ation is an effective method for delineating metalliferous zones. Mult i-site anomalous concentrations of Au and related pathfinder elements occur where subcropping mineralization is covered by till. Regional an d prospect-level biogeochemistry can assist exploration by providing v aluable data to aid in the discovery of buried or blind mineralization .