Application of multivariate data analysis to biogeochemical exploration at the Twin Lakes Deposit, Monument Bay Gold Project, Manitoba, Canada

Abstract

The Twin Lakes Deposit, located in the northwest of the Superior Province, is a promising Archean Greenstone-hosted orogenic gold deposit. Biogeochemical and statistical techniques were used for the first time in this area to assess the geochemical dispersion patterns of Au, As, Bi, Se, Sb, Tl, Fe, Co, Ni, Cr, Mo, Cd, Pb, Zn, Mn, K, P, B, Mg, Ca, Ba, and Cu in black spruce samples collected perpendicularly to the overall trend of shear-hosted gold mineralization. ICP-MS analysis of ashed black spruce bark, twigs, and needles has outlined a biogeochemical response of black spruce to the concealed mineralization. Most elements are accumulated preferentially in twigs and bark, while B, K, Mg, Mn, and P are highly concentrated in needles. High Au and Tl enrichments were identified in all sample types compared to the background level. The scatter plot matrix demonstrated a positive bivariate relationship between Au and Fe, Mg, Cu, Mo, and Zn; and horizontal to slightly negative correlation with Ca, K, Mn, P, and B. Investigations on the spatial distribution pattern of Au and its pathfinder elements using a robust log-transformed inverse distance weighted (IDW) interpolation method revealed the presence of zones of gold enrichment in the north to the northwest of the survey, where Au is accompanied by Tl-As-Cd > Bi, Pb, Se > Sb. According to the Robust RQ-mode principal component analysis (PCA), two main components control the distribution of elements in black spruce, including (1) a geological factor that mostly reflects bedrock composition; and (2) a physiological factor that reflects biological processing of essential elements. Of importance is that Au and its pathfinder elements, including As, Se, Tl, and to a lesser extent, Bi, Cd, and Pb were well-separated as a subgroup of the geological factor with a clear spatial relationship to gold mineralization. This study demonstrates a biogeochemical response in black spruce is associated with gold mineralization at the Monument Bay Gold Project using multivariate statistical methods. The results of this study are promising and can be extrapolated to wider surveys across the Monument Bay Gold Project to vector toward new gold mineralized zones or extensions of the Twin Lakes gold deposit. The results also provide a suite of gold pathfinder elements that support exploration efforts and regional target generation.