Biogeochemical multi-element signatures in common juniper at Mäkärärova, Finnish Lapland: Implications for Au and REE exploration

Abstract

Biogeochemical exploration methods involve chemical analyses of soil organic matter and plant species with a minimal environmental influence. Common juniper (Juniperus communis L.) was assessed as a medium for gold and rare earth element exploration in a shear zone of the Tanaelv Complex, northern Finland. Highest gold concentrations in the juniper twigs spatially coincide with weathered Au-rich hematite–quartz veins in the bedrock. Although gold concentrations were generally low (≤5ppb), the results suggest that the chemical analysis of common juniper is a feasible biogeochemical exploration tool for gold. Concentrations of rare earth elements (REEs) were high in the area where juniper growth was restricted as evidenced by low tissue nutrient concentrations. The restricted growth of REE-rich twigs indicates that they comprised more years of growth compared to other same-sized twig samples. The results indicate that the twigs of common juniper accumulate REEs over time and therefore, in biogeochemical sampling, the twig age should be taken into account. Furthermore, the results suggest that exceptionally dense coverages of Solidago virgaurea L. and Trientalis europaea L. can potentially be used for focusing REE exploration on suitable areas.