Geochemie & Lagerstättenkunde

Study of the paleoproterozoic orogenic gold deposits with atypical metal association of Finland – Focus on the deposits from the Central Lapland Greenstone Belt and the Pohjanmaa Belt

Finland is part of the Fennoscandian Shield, during hundreds of millions of years this region went through several geologic events which led to its actual wealth in mineral deposits. The Svecofennian orogeny between 1,92 and 1,79 Ga deeply deformed and metamorphosed the rocks and led to the formation of mountain ranges where the greenstone belts of Finland are some remnant of these. Like other greenstone belts around the world, the Central Lapland Greenstone Belt (CLGB) and the Pohjanmaa Belt (PB) contain a lot of orogenic gold deposits. However, many orogenic gold deposits of Finland are unusual because instead of being enriched only in gold, they also show economic enrichment in other metals such as Cu, Co, Ni, Ag and U. The processes controlling the enrichment in other metals as gold in the orogenic gold deposits of Finland is not well understood. These atypical deposits occur in the vicinity of gold-only deposits and seem to form during similar events. A detailed study of the mineralisations and dating of hydrothermal minerals will allow to establish the deposition timing of the different deposits while the study of their chemistry will help to better understand the origin of the metals and fluids leading to the formation of the gold-only and atypical deposits. Ultimately this work could provide the industry some new exploration guidelines as the European industry is relying on critical metals such as cobalt for the new technologies development and production. This project is financed by the Bundesanstalt für Geowissenschaften und Rohstoffe (Geological Survey of Germany) and is realized in partnership with the Geologian Tutkimuskeskus (Geological Survey of Finland).