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If we include the Lesjehorrungane ultramafites in the Western Gneiss Region, they would seem to have the best talc potential when it comes to tonnage alone (see Nilsson 1983, -Tegn.-11). Tonnage can here be calculated in millions of tons. On the locations Sjongsosen and Sjong setergrend, modal analyses of representative specimens have shown that talc contents may reach 40-60 % of the rock composition (S. Bakke, pers. com. 1983). Several other places in Lesjehorrungane have also been investigated and sampled, especially south west of Tandesætri, but talc contents here reached maximum c. 30-40 % in modal analyses of representative specimens. However, there might well be local areas somewhat richer in talc than indicated by the numbers cited above. According to old descriptions by Bjørlykke (1905, page 356, 367-369) and Carstens (1918, page 29-33) they have both observed talc rich soapstone at several locations, especially in the western areas of Lesjehorrungane.
The mineral assemblage in Lesjehorrungane as a whole is rather complex. The maximum (prograde) PT assemblage has been forsterite-enstatite-tremolite-chlorite. This assemblage has partly suffered talc-carbonate alteration and partly serpentinisation during retrogression, therefore the metamorphic mineral assemblage all together consists of talc-carbonate-serpentine-chlorite-forsterite-enstatite-tremolite. The assemblage in the most favourable rocks is talc-chlorite-carbonate-enstatite-tremolite. Talc is partly intimately intergrown with chlorite, and partly the two minerals occur side by side as separated flakes and clusters.
Lesjehorrungane is situated in an area with mountain dairy farming (mainly sheep). In addition the area is an important passage for wild reindeer a few times a year. It is however not a nature resort without marks of larger human activities. There are several roads, a very large water magazine for hydroelectric power stations (lake Gautsjøen), a high-voltage transmission line, etc. in the area. The tectono-stratigraphic placement of these sepentinites is inadequately known, and more work is required before reasonable correlations can be proposed.
We can therefore summarise that the talc potential in Lesjehorrungane is very large and possibly attractive if the talc can be satisfactorily extracted, transport problems cleared up and environmental and eventual other area conflicts properly solved.
From Karlsen and Nilsson 1999. |
