Geochemical exploration for gold using groundwater in the deep Canadian Shield

Hydrogeochemical exploration is a promising technique that uses groundwater as a medium to explore for mineral deposits. To evaluate the potential of hydrogeochemistry for gold exploration in the Canadian Shield, we conducted a case study near the Windfall gold deposit, a deep (>1 km) intrusion-related deposit of world-class scale and grade. This unmined deposit, located in a remote area of the Abitibi subprovince, provides an ideal setting to investigate the hydrogeochemical signature of gold mineralization in a cold and humid climate. This study proposes a combined knowledge-based and data-driven multivariate approach to identify dissolved elements that compose the multielement footprint of the Windfall mineralization. Four distinct hydrogeochemical poles (clusters) are defined from hierarchical cluster and principal component analyses: 1) recharge groundwater, 2) recharge-gold groundwater, 3) saline groundwater, and 4) saline-gold groundwater. Multielement enrichment (Ag, Tl, Th, Sn, Bi, U, La, and Ce) associated with ore minerals or alteration minerals is observed in samples of the gold-bearing recharge and saline clusters, and is particularly striking for Ag, Tl, and Th. Gold-type cluster samples, representing the mineralization footprint, are found in an approximately 1 km wide ENE–WSW corridor centered around the Mazères fault, a major ENE-trending regional-scale structure.