Radiometric dating of a quartz-porphyritic potassium rhyolite at Hällefors, south central Sweden

Welin, Eric; Wiklander, Ulf; Kähr, Ann-Marie

doi:10.1080/11035898009455169

Cited by 37 publications

(8 citation statements)

References 5 publications

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“…2) as 1862 Ma (WELIN et al, 1980). This is consistent with the lead model age of the sulphide deposits of central Sweden determined by WICKMAN et al (1968).…”

Section: Discussion On the Genesissupporting

confidence: 86%

Geochemical facies model of ore formation in the Grythyttan-Hällefors area, Bergslagen, Central Sweden

Zakrzewski

1982

Geol Rundsch

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With 8 figures ZusammenfassungDie verschiedenen Eisen-und Manganerz-Bildungen des Grythyttan-H~illcfors-Gebietes zeigen Verhaltnisse auf, die einem systematischen Wechsel der Bedoxbedingungen wiedergeben, yon oxidischer B~indereisenerzbildung bis hin zu stark reduzierten graphitfiihrenden Schiefem. Dieses Phanomen wird durch ein Fazies-Modell erkl~rt. Die unterschiedliehen Mflieu-Bedingungen werden auch als Ursache ffir die geochemische Diferentiation unedler Metall-Ablagerungen in Cu-Erze angesehen, die mit Mineralien assoziiert sind, die Bi, Co, Mo, As, Zn, Pb, Au fiihren und in Pb-Zn-Ag-Erze in Verbindung mit Sb-, Mn-, As-, Sn-und Cu-fiihrenden Mineralien. Die r~iumlichen Beziehungen zwischen Ablagerungen dieser zwei Gruppen und gewissen Eisen-und Mangan-Bildungen weisen auf eine gemeinsame Quelle aller Metalle bin, die m6glicherweise mit exhalativen Derivaten eines basischen Vulkanismus in Verbindung steht. AbstractThe different iron and manganese ore deposits of the Grythyttan-H~illefors area display an arrangement that reflects a systematic change in redox conditions from oxidic banded iron formation into highly reduced graphite-bearing slates. This phenomenon is explained by a facies model. The different environmental conditions are also held to be responsible for the geochemical differentiation of base metal deposits into Cu ores associated with minerals of Bi, Co, Mo, As, Zn, Pb, Au, and Pb-Zn-Ag ores associated with minerals of Sb, Mn, As, Sn, Cu. Spatial relationships between deposits of these two groups and certain iron and manganese deposits point to a common source of all metals, possibly connected with exhalative derivates from basic volcanism. R~sum6Les diff6rents gisements de minerais de Feet Mn de la r6gion de Grythyttan-H~illefors montrent une disposition qui r6fl6te un changement syst6matique dans les ernolitions de r6duction des formations ruban6es de fer oxyd6 en phyllades graphiteux. Ce ph6nom6ne s'explique suivant un mod61e faci6tal. Les diff6rentes conditions de l'environnement sont ainsi rendues responsables de la dfff6rentiation g6oehimique des gisements m6tallif6res de base en minerals de Cu associ6s ~ des min6raux de Bi, Co, Mo, As, Zn, Pb, Au et des minerals de Pb-Zn-Ag associ6s ~ des min6raux de Sb, Mn, As, Sn, Cu. Des relations spatiales entre les gisements de ces deux groupes et eertains gisements de Feet Mn indiquent une source commune pour tousles m6taux, en liaison possible avec des 6manations du volcanisme basique. I~paTx~oe co~epa~aimePas~H~ie 05pa30BaHH~I ~eJIe3HCTI~IX H ~apraH~eB~iX py~ B 05JIaCTH Grythyttan-i~llefors yEaBl~IBa~0T Ha TaKHe BBaHM00TH0~eHH~I, IIpH KOTOpI~IX tIMeJIa l~IeCT0

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“…2) as 1862 Ma (WELIN et al, 1980). This is consistent with the lead model age of the sulphide deposits of central Sweden determined by WICKMAN et al (1968).…”

Section: Discussion On the Genesissupporting

confidence: 86%

Geochemical facies model of ore formation in the Grythyttan-Hällefors area, Bergslagen, Central Sweden

Zakrzewski

1982

Geol Rundsch

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“…The H/illefors silver deposits are located in the Bergslagen mining district which is in the northern part of the Grythyttan-Hfillefors complex of the Central Swedish Svecofenides. The central zone of the complex consists of slates, conglomerates and graywackes, and the eastern part of ore-bearing leptite-like h/illeflintas [rocks with conchoidal fracture, without visible granularity in the main mass although with well-defined phenocrysts of quartz and feldspar, and of ages determined as 1830-t-50 Ma (Moorman et al, 1982) or 1862 Ma (Welin et al, 1980)]. The h/illeflintas have intercalations of carbonate rocks (up to 150 m thick) and greenstones.…”

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confidence: 99%

Some aspects of the silver mineralization in the Hällefors region (Bergslagen, Sweden)

Jasiński¹

1983

Mineral. mag.

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ABSTRACT. Sulphide and sulphosalt mineralization in the H/illefors silver mining district occurs as stratabound bodies in skarn-like black carbonates and other carbonates in the eastern part of the district, and as epigenetic, tectonically controlled vein mineralization in tuffaceous metavolcanics and, to a lesser extent in slates, in the western part.Previous work has suggested that the Ag-bearing Hfillefors deposits were formed by the action of metamorphic solutions on sediments of volcano-sedimentary origin. At the stages of sulphosalt and sulphide formation, temperature and pressure conditions were probably in the ranges 500-440 K and 4.5-3.5 kbar. Examination of a logas-1/T diagram and of Ag-Sb phase relations combined with study of the ores suggest the paragenesis of the Ag-bearing minerals is as follows: allargentum and dyscrasite as exsolution bodies in silver bearing galena; Ag-containing tetrahedrite --. freibergite ~ miargyrite pyrargyrite ~ stephanite (from hydrothermal solutions).

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“…This suggests the contemporaneous development of basinal areas of deposition subject to approximately the same palaeoenvironmental conditions. An early widespread event at 1880 Ma (Welin et al 1980) appears to have been explosive subaerial volcanism of which the Abborrtjarn Tuff is the representative in the Ljusnarsberg area.…”

Section: Stratigraphic Correlation Of the Abborrtjarn Tuff Membermentioning

confidence: 99%

Early Proterozoic Subaerial Volcanism and Its Relationship to Broken Hill-type Mineralization in Central Sweden

Parr

Rickard

1987

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S U M M A RY:Broken Hill-type mineralization is characterized by abundant exhalites in a sulphur-poor, felsic volcanic environment. It is typically Proterozoic. The Ljusnarsberg area in central Sweden is a microcosm of this mineralization type. One part of the amphibolitegrade, supracrustal succession is characterized by a thick sequence of subaerial volcaniclastics which grade into diverse chemical sediments interpreted as exhalities containing sulphide, iron oxide and manganese mineralization. The environment is interpreted as terrestrial with frequent lakes which are fed by volcanic exhalations. Evaporites may also have been present. The non-marine environment may not only have helped determine the nature of the mineralization in the area but also affected the chemistry of the volcanic host rocks. Thus, the occurrence of potassic and sodic metavolcanics may be related to the effects on hydrothermal solution chemistry and water-rock ratios of non-marine surface conditions, as well as alteration temperature and primary volcanic chemistry.Broken Hill-type mineralization is a typically Proterozoic mineralization style characterized by the occurrence of diverse exhalitive deposits in a sulphur-poor environment (cf. Plimer 1984). The exhalites include sulphide, oxide and silicate facies and occur within sequences dominated by felsic volcanism and its pyroclastic derivatives. The oxide facies include banded iron formations sensu law of the small-scale Algoma-type in the Gross (1966) classification. The carbonate facies include calcium and magnesium carbonates, magnetite carbonates and manganese-magnetitecarbonates. End-member silicate facies are represented by cherts, calcsilicate rocks, magnetitecalcsilicates, W-calcsilicates, garnet-quartz rocks, Ba-calcsilicates and gahnite-quartz rocks. Associated sulphide facies include Zn-Pb sulphide and Cu-Pb-Zn sulphide rocks, and magnetite-sulphide-calcsilicates.

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Radiometric dating of a quartz-porphyritic potassium rhyolite at Hällefors, south central Sweden

Cited by 37 publications

References 5 publications

Geochemical facies model of ore formation in the Grythyttan-Hällefors area, Bergslagen, Central Sweden

Geochemical facies model of ore formation in the Grythyttan-Hällefors area, Bergslagen, Central Sweden

Some aspects of the silver mineralization in the Hällefors region (Bergslagen, Sweden)

Early Proterozoic Subaerial Volcanism and Its Relationship to Broken Hill-type Mineralization in Central Sweden

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