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The occurrence, exploration and resources of uranium in Fennoscandia and Estonia are reviewed, from the first observations in the late 19th century to the present resurgence. Production in Finland was 30 tU, in Estonia 60 tU and in Sweden about 200 tU in the 1960s. Total exploration expenditure (in million USD) was 14.0 in Finland (1971-89), 3.2 in Norway (1977-83) and 47.9 in Sweden (1971-85). Government institutions and state-owned companies previously did most of the work but ongoing exploration in Finland and Sweden is carried out by international companies. Because of both poor exposure and the low amount of exploration expenditure, large parts of Fennoscandia can be considered under-explored.
Reasonably Assured Resources (RAR) in Finland and Sweden are currently 1 100 tU and 4 000 tU, respectively. Sweden reports 6 000 tU as EAR (Estimated Additional Resources). Norway does not report any uranium resources at all. In Russia, RAR 2 000 tU and EAR 3 000 tU are reported for the Padma deposit, and RAR 6 000 tU for the Karkku deposit. The largest (low-grade) resources are in Cambrian to Ordovician sediments; the alum shale of Billingen in Sweden is reported to host 300 000 tU.
The Fennoscandian Ore Deposits Database reports 33 uranium deposits and 16 deposits with uranium as a possible by-product. Important uranium provinces are:
1) Cambrian/Ordovician sediments in Sweden, in the Oslo rift in Norway, and within the platform cover from Estonia to Russia,
2) Arjeplog-Arvidsjaur-Sorsele region in northern Sweden,
3) Precambrian windows within the Caledonides in Sweden and Norway,
4) Kittilä-Kolari area in northern Finland, possibly extending to Sweden,
5) Kuusamo area in northern Finland, extending to Russia as the Paana-Kuolajärvi belt,
6) Koli area in eastern Finland, extending southeast to Jänisjärvi in Russia,
7) Uusimaa province in southern Finland, with counterparts in Bergslagen (Sweden) and west of Lake Ladoga (Russia),
8) Onega synclinorium in Russia &
9) the Pasha-Ladoga graben in Russia.
Many of the deposits represent overlapping genetic types. Applicable types of the Red Book classification are unconformity-related (e.g. Karkku), breccia complex (IOCG), quartz-pebble conglomerate, vein, intrusive, volcanic, metasomatite (e.g. Arjeplog) and phosphorite in crystalline bedrock deposits and black shale (e.g. Ranstad) and phosphorite (e.g. Tsjö) in sedimentary deposits. Lithologic, geochemical and radiometric surveys reveal vast areas of suitable source rocks, mostly uraniferous granitoids and migmatites in the Precambrian. Mineralisation events in the crystalline basement range from Paleo- to Mesoproterozoic, with a few occurrences in the Archean. The Lower Paleozoic cover sediments contain uranium resources of low grade but large tonnage in alum shale and phosphorite of Upper Cambrian to Middle Ordovician age. Recent studies suggest mobilisation and deposition of uranium in the basement as late as 450 to 330 Ma ago.
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