Abstract
Early Proterozoic volcanic and sedimentary rocks of the Rappen district in northern Sweden were deposited at a destructive plate margin to the south of the Archaean craton of the western Baltic Shield. The volcano-sedimentary suite was intruded by two generations of early Proterozoic granites at ca. 1.89–1.85 Ga and ca.1.82–1.78 Ga, respectively, and metamorphosed at upper amphibolite facies conditions. Small stratabound iron, copper, and zinc deposits occur in felsic to mafic tuffs and arkosic sediments. Small deposits of molybdenum, tungsten, and uranium formed during the emplacement of the younger granites. The lead isotopic compositions of sulfide trace lead from the various deposits are highly heterogeneous. In the 206Pb/204Pb–207Pb/204Pb diagram they fall on mixing arrays between little evolved early Proterozoic lead and highly radiogenic Caledonian lead. The least radiogenic lead isotopic compositions from the various deposits have a wide range of 207Pb/204Pb ratios and thus indicate variable involvement of Archaean crustal lead in the Proterozoic deposits. Deposits hosted by siliciclastic rocks have higher 207Pb/204Pb ratios than deposits hosted in mafic to felsic tuffites. The lead isotopic heterogeneity suggests that the lead in the various deposits was locally derived and, furthermore, that the sedimentary rocks in part originated from the Archaean craton to the north. Lead mixing arrays in the 206Pb/204Pb–207Pb/204Pb diagram demonstrate that in Paleozoic time radiogenic lead was mobilized and transported in the basement. Source ages calculated from the mixing arrays (ca.1.9 Ga and ca.1.8 Ga) correspond to the age of the Early Proterozoic volcanism and metamorphism respectively. One group of deposits includes lead from at least three sources and illustrates that radiogenic lead was multiply mobilized and transported in the Proterozoic basement. It occurs in deposits that occur in zones that became permeable during the reactivations of the basement.
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References
Adamek, P.M., Wilson, M.R. (1979) The evolution of a uranium province in northern Sweden. Phil. Trans. R. Soc. Lond. A291:355–368
Barton, M.D., Staude, J.-M, Snow, E.A., Johnson, D.A. (1991) Aureole systematics. In: D.M. Kerrick (ed) Contact metamorphism. Rev. Mineralogy 26:723–847
Berthelsen, A. (1987) A tectonic model for the crustal evolution of the Baltic Shield. In: J.-P. Schaer, J. Rodgers (eds) Comparative anatomy of mountain chains. Princeton University Press, pp 31–57
Einarsson, Ö., Forsberg, L.-O., Hålenius, U., Johansson, L., Lindholm, T., Nisca, D.H., Ottosson, D., Rankvist, T. (1989) Rappenområdet [The Rappen district]. (Unpubl. NSG report; in Swedish). PRAP 89044
Gaál G., Gorbatschev R. (1987) An outline of the Precambrian evolution of the Baltic Shield. Precambrian Res. 35:15–52
Grip, E. Frietsch, R. (1973) Malm i Sverige 2 [Ores in Sweden 2] (in Swedish). Almqvist & Wiksell, Stockholm, 295 p
Hanson, R.B., Barton, M.D. (1989) Thermal development of low- pressure metamorphic belts: results from two-dimensional numerical models. J. Geophys. Res. 94:10363–10377
Johansson, A. (1983) Lead isotope composition of Caledonian sulfide-bearing veins in Sweden. Econ. Geol. 78:1674–1688
Johansson, A., Rickard, D. (1984) Isotopic composition of Phanerozoic ore leads from the Swedish segment of the Fennoscandian Shield. Mineral.Deposita 19: 249–255
Nordkalott Project (1988) Metamorphic, structural and isotopic age map, Northern Fennoscandia. 1∶1 mill. Geol. Surv. Finl. Norw. Swed.
Öhlander, B. (1986) Proterozoic mineralizations associated with granitoids in northern Sweden. Sver. Geol. Unders. Ca65:39 p
Öhlander, B., Billström, K. (1989) Regional implications of U-Pb zircon dating of two Proterozoic granites associated with molybdenite mineralized aplites in northern Sweden. Geol. Fören. Stockholm Förh. 111:229–238
Padget, P. (1966) The geology and mineralization of the Radnejaure area, Norrbotten county, Sweden. Sver. geol. Unders C609:60p
Pharaoh, T.C., Pearce, J.A. (1984) Geochemical evidence for the geotectonic setting of early Proterozoic metavolcanic sequences in Lapland. Precambr. Res. 25:283–208
Rickard, D.T. (1978) The Svecokarelian anomalous ore lead line. Geol. Fören. Stockholm Förh. 100:19–29
Rickard, D.T., Willden, M.Y., Marinder, N.-E., Donnelly, T.H. (1979) Studies on the genesis of the Laisvall sandstone lead-zinc deposit, Sweden. Econ. Geol. 74:1255–1285
Romer, R.L. (1989) Trace lead composition of sulfides from mineralizations in the Proterozoic Råppe supracrustal belt, northern Sweden. Geol. Fören. Stockholm Förh. 111:155–160
Romer R.L. (1990) Lead mobilization during foreland metamorphism in orogenic belts: examples from northern Sweden. Geol. Rundsch. 79, 693–707
Romer, R.L. (1991) The Late Archaean to Early Proterozoic lead isotopic evolution of the Northern Baltic Shield of Norway, Sweden and Finland. Precambr. Res. 49:73–95
Romer, R.L. (1992) Vesuvianite-a new tool for the U-Pb dating of skarn ore deposits. Mineral. Petrol. (in press)
Romer, R.L. (1992) Caledonian upgrading of Proterozoic low-grade base-metal deposits in northern Sweden. Mineral. Petrol. (in press)
Romer, R.L., Bax, G. (1992) The rhombohedral framework of the Scandinavian Caledonides and their foreland. Geol. Rundsch. 81:391–401
Skiöld, T. (1988) Implications of new U-Pb zircon chronology to early proterozoic crustal accretion in northern Sweden. Precambr. Res. 38:147–164
Sundblad, K. (1991) Evidence for pre-Svecofennian influence in the Proterozoic Cu-Zn-Pb sulphide deposits at Tjåmotis, northern Sweden. Geol. Fören. Stockholm Förh. 113:64–65
Sundblad, K., Røsholt B. (1986) A lead isotopic study of galena and amazonite in the Kiuri-Rassåive sulphide deposit-consequences for the timing of the ore forming processes in the Proterozoic of northernmost Sweden. 17:e Nordiska Geologmötet, Helsinki, 196
Vaasjoki, M. (1981) The lead isotopic composition of some Finnish galenas. Geol. Surv. Finl. Bull. 316:1–30
Vaasjoki, M. (1988) Zircon U-Pb versus Rb-Sr whole rock age data from eastern Finland: a critical comment on the papers of Barbey & Martin and Martin, Precambrian Research, vol 35. Precambr. Res. 39:217–219
Vaasjoki, M., Sakko, M. (1988) Evolution of the Raahe-Ladoga zone in Finland: isotopic constraints. Geol. Surv. Finl. Bull. 343:7–32
Vaasjoki, M., Vivallo, W. (1990) New lead isotope determination from five Proterozoic sulfide deposits, Skellefte district, Sweden. Mineral. Deposita 25:50–56
Walser, G., Einarsson, Ö. (1982) The geological context of molybdenum occurrences in the southern Norrbotten region, northern Sweden. Geol. Rundsch. 71:213–229
Weihed, P., Schöberg, H. (1991) Age of porphyry-type deposits in the Skellefte District, northern Sweden. Geol. Fören. Stockholm. Förh. 113:289–294
Wilson, M.R., Hamilton, P.J., Fallick, A.E., Aftalion, M., Michard, A. (1985) Granites and early Proterozoic crustal evolution in Sweden: evidence from Sm-Nd, U-Pb and O isotope systematics. Earth Planet. Sci. Lett. 72:376–388
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Romer, R.L. Metallogeny and lead isotopic composition of base metal sulfide deposits in the Rappen area, northern Sweden. Mineral. Deposita 28, 37–46 (1993). https://doi.org/10.1007/BF00199008
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DOI: https://doi.org/10.1007/BF00199008