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- Öhlander, Björn
(author)
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Geochemical analyses of rocks of the Haparanda suite, northern Sweden
- 1984
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In: Geologiska föreningens i Stockholm förhandlingar. - : Informa UK Limited. - 0016-786X. ; 106:2, s. 167-169
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Journal article (peer-reviewed)abstract
- Thirteen samples of the primorogenic Haparanda suite (gabbro to granodiorite) in northernmost Sweden were analysed for major elements and the trace elements Rb, Sr, Ba, Cu, Zn, Mo, Sn, Be, Nb, Y, Zr, Cr, Ni, V, F, Cl and S. The results accord with the view that the Haparanda suite is an I-type rock suite generated in a compressional environment. The Sn-content is higher than expected, but Sn, Mo and Be are not enriched in the most silicic samples. The F-content is higher in gabbros and Mo is correlated with Cu.
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- Berglund, S., et al.
(author)
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Arsenopyrite and sphalerite as T-P indicators in sulfide ores from northern Sweden
- 1980
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In: Mineralium Deposita. - 0026-4598 .- 1432-1866. ; 15:2, s. 175-187
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Journal article (peer-reviewed)abstract
- The compositions of arsenopyrite and sphalerite from five Swedish metamorphosed Cu, Zn-sulfide deposits are related to T and P, according to the methods described by Kretschmar and Scott (1976) and Scott (1973). The As/S ratio of arsenopyrite indicates an equilibrium temperature around 400°C for all the deposits studied, whereas the sphalerite barometer shows pressures between 5 and 7 kb. The mineral assemblages of the bedrocks indicate a similar temperature but a lower pressure. A constant fs2 is probably only effective over distances of millimetres or a few centimetres in the samples studied. The fs2 has always been lower in the surrounding rocks than in the ores as indicated by a higher As/S in arsenopyrite, more FeS in sphalerites and the absence of pyrite.
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- Billström, Kjell, et al.
(author)
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U-Pb zircon age of the Rostberget W-occurrence, northern Sweden
- 1989
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In: Geologiska föreningens i Stockholm förhandlingar. - : Informa UK Limited. - 0016-786X. ; 111:2, s. 121-126
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Journal article (peer-reviewed)abstract
- Anomalously U-rich granites of the so-called Revsund type, associated with W- and Sn-enrichments, occur in the Gunnarn area close to Storuman in northern Sweden. At Rostberget, a swarm of thin undeformed wolframite-bearing greisen veins are situated in the interior of the Joran granite intrusion. We have dated zircons from a sample of the greisen veins with the U-Pb method. The veins are less than 1 cm wide and it is likely that the sample also contains zircons from the immediately surrounding altered granite. The mineralizing event and connected metasomatic processes probably released Zr from the granite which became available for zircon growth processes in the greisen veins. One notable feature, probably due to the greisen-forming processes, is the very high common Pb concentrations characterizing the zircons. By varying the assumed common Pb composition in the calculations, the effect on resulting intercept ages has been evaluated. The obtained age interval (1775-1782 Ma) is typical of formation ages for Revsund granites, which indicates that the mineralization event at Rostberget followed closely upon the granite emplacement. We conclude that the Revsund-type granites, which cover large areas, were generated in a narrow time interval 1790-1775 Ma ago.
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