Lead isotopic evidence for the origin of 1.8-1.4 Ga ores and granitoids in the southeastern part of the Fennoscandian Shield

Lead isotope systematics in the Långban deposit and adjacent sulphide mineralisations in western Bergslagen, Sweden

“…rather similar to the data of Jarl & Johansson (1988). Sundblad (1991) suggested that the isotopic composition of galena ( 206 Pb/ 204 Pb ¼ 15.78,207 Pb/ 204 Pb ¼ 15.32 and 208 Pb/ 204 Pb ¼ 35.32 as the least radiogenic ratios; R in Fig. 4) from the 1.80 Ga TIB granite-hosted sulphide mineralisation at Ramnebo in Småland, south-eastern Sweden (Ahl 1989), should represent a good approximation of the Pb component in c.1.8 Ga TIB magmas in Småland.…”

“…However, these also included deposits of a more debatable origin, such as Gruvåsen (Hellingwerf 1986) and Hällefors (Hedström 1984;Zakrzewski & Nugteren 1984;Wagner et al 2005) in western Bergslagen. The published lead isotope data 224 Jonsson and Billström: Lead isotope systematics in western Bergslagen, Sweden GFF 131 (2009) from the Gruvåsen deposit are similar to those from Lahäll and Myssberget, whereas data from Hällefors are even more radiogenic (Sundblad 1991;Romer & Wright 1993; this study).…”

“…By contrast, there are also vein-type ores in the Hällefors fields, and this style of mineralisation has been interpreted as the result of locally extensive remobilisation of components from the syn-volcanic ores (Hedström 1984;Zakrzewski & Nugteren 1984;Wagner et al 2005). The origin of the Hällefors mineralisations is controversial and both a granitic origin (Sundblad 1991) and a volcanic-exhalative origin have been proposed (e.g. Hedström 1984;Zakrzewski & Nugteren 1984).…”

“…3A) and reference fields for TIB granites, granite-related mineralisations, as well as Svecofennian source compositions (G, Grythyttan; F, Falun; U, Utö/Stockholm archipelago; Sundblad 1994) in the Bergslagen region. DJ1 -2 comprise data from mineralisations related to TIB granites of "Dala-Järna type" according to Johansson & Rickard (1985), L for Lisjön veins and Gr for Gruvåsen data (Sundblad 1991). The lead isotope composition of 1.80 Ga TIB magmas is estimated using three data sources; FG, feldspar data of Jarl & Johansson (1988), R, Ramnebo galena data of Sundblad (1991) and TIB fs, feldspar Pb data of Ohlsson (2002).…”

“…DJ1 -2 comprise data from mineralisations related to TIB granites of "Dala-Järna type" according to Johansson & Rickard (1985), L for Lisjön veins and Gr for Gruvåsen data (Sundblad 1991). The lead isotope composition of 1.80 Ga TIB magmas is estimated using three data sources; FG, feldspar data of Jarl & Johansson (1988), R, Ramnebo galena data of Sundblad (1991) and TIB fs, feldspar Pb data of Ohlsson (2002). Constructed Pb evolution curve for m ¼ 9.94 starts at Falun source composition (F) and the successive points denote the isotopic composition of the evolved Pb at 1850 and 1783 Ma, respectively.…”