Most of the known platinum group element (PGE) resources in Finland are in contact- and reef-type deposits in 2.45 Ga mafic-ultramafic layered intrusions. These intrusions also have the potential to contain the majority of possibly existing, yet undiscovered, PGE resources in Finland. The undiscovered Pt, Pd, Au, Ni, and Cu resources in contact- and reef-type deposits were estimated down to one kilometre depth using the three-part quantitative assessment method. This included the delineation of 19 contact-type and 24 reef-type permissive tracts, formation of a grade-tonnage model for the contact-type deposits and a separate model for each reef-type tract, estimation of the number of undiscovered deposits for each permissive tract, and Monte Carlo simulation to produce the frequency distributions of metal tonnages in the undiscovered deposits. The expected numbers of undiscovered contact- and reef-type deposits are 29 and 23, respectively. At the 50% probability level, these deposits contain at least 5,600 t Pt, 12,000 t Pd, 430 t Au, 4.2 Mt Ni, and 5.7 Mt Cu. Of this undiscovered resource, 88% of the Pt, 81% of the Pd, 60% of the Au, 50% of the Ni and 37% of the Cu is contained in reef-type deposits. The Koitelainen intrusion alone is estimated to contain 48% of all undiscovered Pt and 44% of Pd. The intrusions of the Portimo complex host about a third of the number of both the known and the expected undiscovered PGE deposits, but only 11% of the Pt and 14% of the Pd in the undiscovered resources. The Western Intrusion of the Koillismaa Complex is assessed to contain 20% and 21% of the undiscovered Pt and Pd, respectively. The known PGE resources in Finland are 91 t Pt and 237 t Pd in seven deposits, including the atypical Kevitsa deposit that alone contains 21% of the known Pt+Pd resources. Hence, the presently known deposits account for around 2% of the total assessed PGE endowment in Finland. However, this work gives no guarantee on how much of the estimated PGE will ever be discovered.
Keywords (GeoRef Thesaurus, AGI): platinum ores, layered intrusions, potential deposits, platinum, palladium, gold, nickel, copper, resources, evaluation, ore grade, tonnage, quantitative analysis, Proterozoic, Finland
Kalevi Rasilainen, Pasi Eilu
Geological Survey of Finland, P.O. Box 96, FI-02151 Espoo
Geological Survey of Finland, P.O. Box 1237, FI-70211 Kuopio
Markku Iljina, Tuomo Karinen
Geological Survey of Finland, P.O. Box 77, FI-06101 Rovaniemi
E-mail: kalevi.rasilainen gtk.fi