BIOGEOCHEMICAL SURVEY ON THE OVERMAN DEPOSIT; AN ASSESSMENT ON THE EFFECTIVENESS OF BIOGEOCHEMICAL METHODS FOR GOLD EXPLORATION IN A PRIMARY SURINAMESE TROPICAL RAINFOREST

To date there have been no significant published reports on biogeochemical exploration techniques in Suriname. The applicability of this method for gold exploration in Suriname was tested on the Overman deposit within the Charmagne project area of the IAMGOLD corporation. Orientation surveys in the primary tropical rainforest have revealed that the Walaba tree (Eperua Falcata), a deep rooted plant, and the Paramaca palm (Astrocaryum Paramaca), a shallow rooted plant, are the two species which enable good geochemical coverage across the deposit. Bark samples of the Walaba tree and leaf samples of the Paramaca palm were sampled, this because of the ease to sample these tissues and tendencies of plants to store metals in bark and in fresh leafs. The collected samples were dried in open air and a heating oven at 60˚ C for upto 5 days before being ground, split and ashed in a muffle furnace. Afterwards the ash samples were analyzed by ICP-MS by ALS in Canada. Profiles of lines indicate the anomalies of gold from the plant ash correlate relatively well with the gold anomalies derived from soil samples obtained by conventional shallow augering. Elements such as As, Ag, Co, Sb, W and Pb which are potential pathfinders for gold in the Overman area (Iamgold-unpublished, 2012) seem to be taken up by the plants and correlate relatively well with gold. Plants were sampled no more than 20 meters from shallow auger locations. The Pearson correlation coefficient was calculated between all the elements and gold in the ICP-MS data sets for each plant species sampled. The best correlation coefficients out of these data sets show values ranging from 0.24 to -0.25. From previous Iamgold internal studies the same range is observed in multi-element data of soil and rock pulp from diamond core samples. Multi-element data of the same diamond core pulps were analyzed for this study with a portable desktop XRF unit. The same pathfinder elements associated with gold based on the XRF analyses are correlated with gold in the sampled vegetation. These correlations and the relative ease of sampling vegetation makes biogeochemical exploration techniques a worthy tool for first phase gold exploration the primary rainforest of Suriname. Further studies are justified in various regolith profiles.