Biogeochemical Prospecting for Gold using Robust Multivariate Statistical Analysis
Abstract
The application of biogeochemical techniques in mineral exploration is to use the chemistry of plants to identify the presence and characterizations of concealed mineralization. Gold prospecting using biogeochemical techniques is found to be a viable geochemical tool in the early stages of exploration. This study aims to use a systematic two-phase statistical approach, including process discovery and process validation, to evaluate the multi-element biogeochemical dataset and identify the geochemical process controlling elemental occurrence and distribution in plant samples. To achieve these objectives, three biogeochemical surveys were conducted over the early and advanced gold targets located at two economically promising Archean greenstone-hosted orogenic gold deposits: including the Monument Bay Gold Project (MBGP) and Yellowknife City Gold Project (YCGP). The MBGP is a highly prospective gold deposit located in the northeastern part of Manitoba. The YCGP is a region of intense exploration and drilling near the extensions of the gold-bearing shear zones that host the historic Giant and Con Mines, located close to the city of Yellowknife, Northwest Territories.
Exploratory data analysis (EDA), including univariate and multivariate statistical analysis, was used to interpret biogeochemical data and identify the plant-substrate relationship and, subsequently, zones of gold enrichment. The results of EDA indicated that black spruce can successfully accumulate anomalous values of Au and its pathfinder elements, including As, Ag, Bi, Se, Sb, and Tl. Therefore, it is the preferred plant species for biogeochemical exploration in Canadian boreal forests. In addition, the Inverse distance weighted (IDW) interpolation method demonstrated strong associations between Au and its pathfinder elements. It is revealed that zones of Au enrichments are associated with different sets of pathfinder elements based on the bedrock composition and mineralization style. Arsenic, Se, Tl, and Sb signatures accompanied Au in both MBGP and YCGP. According to the principal component analysis (PCA), the geochemical/ mineralization and physiological factors control elemental distribution in black spruce. The results of this study attest to the robustness of multivariate statistical analysis in detecting zones of Au enrichment using biogeochemical exploration methods.