Metamorphism and deformation of a Palaeoproterozoic polymetallic sulphide-oxide mineralisation: Hornkullen, Bergslagen, Sweden
2016 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 138, no 3, 410-423 p.Article in journal (Refereed) Published
The Hornkullen mineralisation is situated in the westernmost part of the Bergslagen ore province, south-central Sweden. Here, polymetallic sulphides and oxides are hosted by an inlier of Svecofennian, c. 1.9Ga skarn-bearing metavolcanic units, enclosed in the c. 1.8Ga Filipstad granite belonging to the Transscandinavian Igneous Belt. The Ag- and Au-bearing mineralisation is dominated by veins and impregnations of magnetite, pyrrhotite, galena, chalcopyrite and arsenopyrite with subordinate pyrite, sphalerite, ilmenite, lollingite, Pb-Fe-Ag-Cu-Sb sulphosalts and rare gudmundite, pentlandite and molybdenite. Overall, a detailed textural and mineralogical study of the ore assemblages suggests significant deformation and remobilisation at high temperature, which is corroborated by sulphide geothermobarometry. The arsenopyrite geothermometer yields an average temperature of c. 525 degrees C, which is likely to be the result of metamorphic re-equilibration. Sphalerite geobarometry gives peak pressures of c. 300-400MPa, albeit with caveats. The combined observations suggest that the present mineralogical and textural nature of the ore assemblages at Hornkullen is primarily related to remobilisation during Svecokarelian regional metamorphism of a pre-existing, most likely syn-volcanic mineralisation. This scenario is likely to be applicable to many other Svecofennian metasupracrustal-hosted deposits in the Bergslagen ore province.
Place, publisher, year, edition, pages
2016. Vol. 138, no 3, 410-423 p.
Hornkullen; Bergslagen; polymetallic sulphide sulphosalt remobilisation; metamorphism; deformation; sulphide geothermobarometry
Earth and Related Environmental Sciences
Research subject Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
IdentifiersURN: urn:nbn:se:uu:diva-293826DOI: 10.1080/11035897.2015.1135187ISI: 000381491500004OAI: oai:DiVA.org:uu-293826DiVA: diva2:928296
FunderSwedish Research Council