Abstract

Transported regolith cover hinders exploration for economically important komatiite-hosted sulphide ore bodies in the Yilgarn Craton. Biogeochemistry offers a surface sampling technique to explore for these buried deposits that has not been extensively tested in this region. In this study, eucalypt trees and some other common plants were investigated at the North Miitel Ni deposit for their use in exploration targeting and to understand what role vegetation is taking in creating near surface anomalous geochemical signatures. Primary ore is deep (c. 400 m) with a thin, weakly-enriched (compared to primary mineralisation), in situ weathered zone 10–20 m below the surface, under a cover sequence of 5–10 m deep. This study investigated the efficacy of several sample media including leaves, bark, litter, and organic-rich soils in an orientation traverse and a more extensive (150 m - spaced, 9 km2) grid-based survey (footprint). The organic-rich soil and biogeochemistry were influenced by contamination from the haul road. Directly over mineralisation some elements showed anomalous concentrations but data were erratic, not statistically significant and, therefore, not useful for mineral exploration. High groundwater salinity and low pH, lack of supergene development, weak subsurface signature and aeolian contamination contribute to why Ni anomalies have not been readily indentified at the surface. Nickel is also essential to plant physiology and is actively absorbed in a controlled manner. Investigation of plant-soil-water interactions is valuable in understanding metal mobility in the environment. Here we refined the viable exploration techniques in this setting where Ni sulphide discoveries through cover are important for future economic and resource development.

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