Davidite-loveringite in early Proterozoic albite felsite in Finnmark, north Norway
situated within the Kautokeino volcano sedimen-tary belt of early Proterozoic age in Norway's northernmost county, Finnmark. This belt is dominated by basic volcanic rocks, but also in-cludes two thick formations of sandstone and quartzite (Siedlecka et al., 1985). Both continental rifting (Tor...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.587.1453 http://www.minersoc.org/pages/Archive-MM/Volume_52/52-366-400.pdf |
| Summary: | situated within the Kautokeino volcano sedimen-tary belt of early Proterozoic age in Norway's northernmost county, Finnmark. This belt is dominated by basic volcanic rocks, but also in-cludes two thick formations of sandstone and quartzite (Siedlecka et al., 1985). Both continental rifting (Torske, 1978; Witschard, 1980) and ensialic back-arc basin situations (Pharaoh and Pearce, 1984) have been suggested as depositional en-vironments for the supracrustals. The rocks were deformed by the Sveco-Karelian Orogeny and metamorphosed in the amphibolite facies. The Biggejavri mineralization (Olerud, 1985) consists of a uranium, scandium and rare-earth-bearing albite felsite found near the top of the tholeiitic basalt sequence of the Suoluvuobmi Formation (Solli, 1983), which is one of the lower units of the Kautokeino volcano-sedimentary belt. The volcanites are succeeded by schists of the same formation. Field evidence shows that the emplace-ment of albite felsite was probably pre-deforma-tional, and detailed and regional mapping indicate a stratabound character for the rock. A slightly radioactive granular albite felsite also occurs as post tectonic dykes. The origin of the albite felsite is currently under study. The radioactive albite felsite is medium to fine grained and consists of more than 90 ~ albite. The rock also contains a Cr- and V-rich variety of davidite-loveringite, calcite, quartz, muscovite, chromite and rutile. Accessories are La-Ce car-bonates, monazite, orthite, thortveitite, coffinite, uranophane, brannerite, zircon, pyrite, sphalerite |
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