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Mn-silicate skarns from the Gåsborn area, West Bergslagen, central Sweden

Published online by Cambridge University Press:  05 July 2018

Arend H. Damman
Arend H. Damman*
Affiliation:
Institute of Earth Sciences, Free University, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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Abstract

In the Gåsborn area, West Bergslagen, central Sweden, Mn-silicate-magnetite-jacobsite skarns were formed as the result of three successive processes. (1) Deposition of exhalative-sedimentary manganiferous iron-ore-bearing sediments together with cherts and volcanics. (2) Intrusion of a synvolcanic anorogenic granite and some slightly younger gabbros and tonalites: under influence of these intrusives the manganiferous iron-ore-bearing sediments were metamorphosed into (a) rhodonite(I)-magnetite-pyrophanite-garnet assemblages; (b) (manganiferous) hedenbergite(I)-allanite-titanite-garnet-magnetite assemblages; (c) tephroite-jacobsite-pyrophanite-garnet assemblages and (d) magnetite-bearing quartzites. (3) Release of hydrothermal fluids from the granite and subsequent alteration of the above assemblages into metasomatic infiltration skarns, consisting of rhodonite(II), garnet, hedenbergite(II), biotite, actinolite or edenite (with up to 20.11 wt.% MnO), chlorite, bementite, fluorite, helvite, rhodochrosite, hematite, rutile and accessory galena, sphalerite, wittichenite, aikinite, pyrrhotite, chalcopyrite and pyrite.

The maximum temperature (T) and pressure (P) during contact metamorphism are estimated at 550°C and 1.0 kbar respectively. The fluid under influence of which the metasomatic infiltration skarns were formed was relatively rich in Fe, Cl and F and carried little or no Mg and Mn.

During early diagenesis (beginning of stage 2) fo2 was between the hematite/magnetite (hm/mt) and the hausmannite + hematite = jacobsite buffers (h + m = j). During stage 2, with increasing T, fo2 changed from above to below hm/mt. Magnetite and jacobsite at some distance from the hydrothermal veins from which the metasomatic skarn-forming fluids were released, were altered during stage 3 into hematite. Magnetite in, and close to the hydrothermal veins was not altered to hematite, implying an increase in fo2 to above hm/mt with increasing distance from these veins.

Keywords

manganese silicateskarnmagnetitejacobsiteGåsbornSweden
Type
Silicate Mineralogy
Information
Mineralogical Magazine , Volume 53 , Issue 373 , December 1989 , pp. 613 - 624
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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References

Åberg, G., Bollmark, B., Björk, L. and Wiklander, U. (1983a) Geol. För. Förh. 105, 78-81.CrossRefGoogle Scholar
Åberg, G., Levi, B. and Frederiksson, G. (1983b) Ibid. 105, 199-203.CrossRefGoogle Scholar
Abrecht, J. (1980) Contrib. Mineral. Petrol. 74, 253-60.CrossRefGoogle Scholar
Abrecht, J. and Peters, T. (1975) Ibid. 50, 241-6.Google Scholar
Abs-Würmbach, I. and Peters, T. (1981) Fortschr. Mineral. 59, 4-5.Google Scholar
Baker, J. H. (1985) Ph.D. thesis, GUA papers of geology. Series 1, No. 21, 204pp.Google Scholar
Burton, J. C., Taylor, L. A. and Chou, I-Ming (1982) Econ. Geol. 77, 764-84.CrossRefGoogle Scholar
Candia, M. A. F., Peters, T. and Valarelli, J. V. (1975) Contrib. Mineral. Petrol. 52, 261-6.CrossRefGoogle Scholar
Damman, A. H. (1988a) Geol. Mijnbouw 67, 433-42.Google Scholar
Damman, A. H. (1988b) Mineral. Mag. 52, 193-200.CrossRefGoogle Scholar
Damman, A. H. (1989a) Ph.D. thesis, the Free University, Amsterdam, in press.Google Scholar
Damman, A. H. (1989b) Am. Mineral. 74, 573-85.Google Scholar
Damman, A. H. and Kieft, K. (1989) Submitted to Can. Mineral. Google Scholar
Dasgupta, H. C. and Manickavagasam, R. M. (1981) J. Petrol. 22, 363-96.CrossRefGoogle Scholar
de Groot, P. A., Baker, J. H. and Oen, I. S. (1988) Geol. Mijnbouw 67, 19-29.Google Scholar
Easton, A. J., Joslin, I. E., Kempe, D. R. C. and Hancock, J. M. (1982) Marine Geology 7, 401-4.Google Scholar
Einaudi, M. T., Mehnert, L. D. and Newberry, R. J. (1981) Econ. Geol. 75th Aniversary Volume, 317-91.Google Scholar
Gamble, R. P. (1976) Geol. Soc. Am. Abstract with Program 3, 8, 879.Google Scholar
Gamble, R. P. (1978) Ph.D. thesis, Yale University, 226 pp.Google Scholar
Geyer, P. and Magnusson, N. H. (1944) Sver. Geol. Unders., Ser. Ca, 35, 654 pp.Google Scholar
Hsu, L. C. (1968) J. Petrol. 9, 40-83.CrossRefGoogle Scholar
Hsu, L. C. (1980) Contrib. Mineral. Petrol. 71, 407-15.CrossRefGoogle Scholar
Jarl, L.-G. and Johansson, A. (1988) Geol. För. Föth. 110, 21-8.CrossRefGoogle Scholar
Magnusson, N. H. (1925) Kungl. Kommerskollegium. beskrivning over Mineralfyndigheter, Stockholm 2, 231 pp.Google Scholar
Magnusson, N. H. (1929) Sver. Geol. Unders., Ser. Ca, 13, 140pp.Google Scholar
Magnusson, N. H. (1930) Ibid. 23, 111 pp.CrossRefGoogle Scholar
Magnusson, N. H. (1970) Ibid. 643, 127 pp.Google Scholar
Miyano, T. and Beukes, N. J. (1987) Econ. Geol. 82, 706-18.CrossRefGoogle Scholar
Oen, I. S. (1987) Precambrian Res. 35, 36-82.CrossRefGoogle Scholar
Oen, I. S. and Verschure, R. (1982) Geol. Mijnbouw 61, 301-4.Google Scholar
Oen, I. S. and Wiklander, U. (1982) Ibid. 61, 309-12.Google Scholar
Oen, I. S., Helmers, H., Verschure, R. H. and Wiklander, U. (1982) Geol. Rundsehau 71, 182-94.CrossRefGoogle Scholar
Oen, I. S., Verschure, R. and Wiklander, U. (1984) Geol. Mijnbouw 63, 55-88.Google Scholar
Patchett, P. J., Gorbatschev, R. and Todt, W. (1987) Precambrian Res. 35, 145-60.CrossRefGoogle Scholar
Peacor, D. R. and Essene, E. J. (1982) Am. Mineral. 65, 335-9.Google Scholar
Peters, T., Schwander, H. and Tromsdorff, V. (1973) Contrib. Mineral. Petrol. 42, 325-32.CrossRefGoogle Scholar
Robinson, P., Spear, F. S., Schumacher, J. C., Laird, J., Klein, C., Evans, E. W. and Doolan, B. L. (1982) Reviews in Mineral. 9b, Min. Soc. America. 1-228.Google Scholar
Roy, S. (1981) Manganese Deposits. London, Academic Press, 458 pp.Google Scholar
Tegengren, F. T. (1924) Sver. Geol. Unders. ser. Ca 17, 406 pp.Google Scholar
Welin, E., Gorbatschev, R. and Lundegardh, P. H. (1977) Geol. För. Förh. 99, 363-7.CrossRefGoogle Scholar