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- Romer, Rolf L., et al.
(författare)
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Pb-Sr-Nd isotope data from the Valasjaure supracrustal belt, northern Sweden
- 1989
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Ingår i: Geologiska föreningens i Stockholm förhandlingar. - : Informa UK Limited. - 0016-786X. ; 111:3, s. 239-246
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Tidskriftsartikel (refereegranskat)abstract
- The Valasjaure supracrustal belt at the eastern border of the Swedish Caledonides consists predominantly of basic volcanic and volcanocalstic rocks, which form a c 10km long N-S striking belt, Cu-mineralizations occur in the central part of the belt, associated mainly with albitites and to a minor degree with chlorite schists and metatuffs. Isotopic data from plagiclase-porphyries, basalts, and the mineralized zone indicate that the last isotopic homogenization of these rocks in the Valasjaure supracrustals occurred c1.6-1.7Ga ago. This age has been related to the greenschist facies metamorphism and represents a minimum age for the belt. The greenschist facies metamorphism was probably related to the late- and post-Svecofennian intrusion of granites in northern Sweden. The isotopic systems became further disturbed prior to or during the Caledonian overthrusting, when minor lead from an upper crustal source was added.
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- Romer, Rolf L.
(författare)
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Trace lead composition of sulfides from mineralizations in the Proterozoic Rappe supracrustal belt, northern Sweden
- 1989
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Ingår i: Geologiska föreningens i Stockholm förhandlingar. - : Informa UK Limited. - 0016-786X. ; 111:2, s. 155-160
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Tidskriftsartikel (refereegranskat)abstract
- At Rappe (30 km NW of Kiruna), basic to intermediate volcanites, volcanogenic sediments, and schists with intercalated carbonates form a supracrustal belt which encloses minor Cu-Fe and Zn-Pb impregnations. In addition, Zn-Pb mineralizations occur in discordant veins. The trace lead compositions from pyrrhotites and sphalerite from these mineralizations define an anomalous lead line, which is interpreted as a mixing line. The mixing, which is associated with the remobilization of the Zn-Pb mineralizations probably occurred in connection with the Caledonian orogeny. The added radiogenic lead was leached locally from the surrounding upper crustal rocks and has, therefore, locally varying isotopic composition, as illustrated by the differences in lead composition from mineralizations in the Viscaria, Pahtohavare, and Rappe supracrustal belts
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