Ore deposition in a proterozoic incipient rift zone environment: a tentative model for the Filipstad-Grythyttan-Hjulsjö region, Bergslagen, Sweden

Oen, I. S.; Helmers, H.; Verschure, R. H.; Wiklander, Ulf

doi:10.1007/bf01825035

Cited by 75 publications

(57 citation statements)

References 4 publications

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“…Here, the Mg-rich schists form discordant, Iensoid zones trending parallel to the general foliation, a proposed axis of rifting and the long axes of tectonic basins (OEN et al, 1982). BAKet~ and D~GRooT argue convincingly that the Mg-rich schists were formed by seawater-rock interaction.…”

Section: Secondary Alterationsmentioning

confidence: 95%

Hydrothermal alteration as a control of regional geochemistry and ore formation in the central Baltic Shield

Lagerblad

Gorbatschev

1985

Geol Rundsch

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ZusammenfassungUber 1000 proterozoische Eruptivgesteine der vulkanisch-sediment~iren Erzprovinz in Mittelschweden wurden auf Haupt-bzw. Spurenelemente analysiert. Die Gesteine bilden eine Folge mit Schwerpunkt auf basaltischen und insbesondere rhyolitischen Zusammensetzungen, w~ihrend Andesite nur schwach vertreten sind. Die prim~irmagmati-sche Zusammensetzung hat wenig Bezug zu den Erzen, die genetisch gr61~tenteils an sekund~ire Ver~nderungen gebunden sind. Hydrothermale Metasomatose hat eine regionale Verbreitung. Auch von den makroskopisch intakten, 732 analysierten, sauren porphyrischen Eruptivgesteinen sind mehr als die H~ilfte durchgreifend ver~indert. Die metasomatischen Prozesse fiihrten zu extremer Natriumund Kaliumdifferenzierung und zu Fe-Mg-Si-Beziehungen, die nicht auf magmatische Differentiation zuriJckzufiihren sind. Anreicherung von Na und Mg und Auslaugen der erzbildenden Metalle treten in den tieferen Teilen der vulkanischen Schichtenfolge auf. Die h6heren Lagen wetden von kalireichen Metavulkaniten, Karbonatgesteinen und vulkanogenen, erzassoziierten Sedimenten beherrscht. Metasomatische Gesteinsumwandlung und Erzbildung sind zwei Teilprozesse einer grof~riumigen hydrothermalen Konvektion, durch die Meereswasser durch die Schichtenfolge getrieben wurde. Die erzbildenden chemischen Bestandteile wurden dabei den tieferen Teilen des Vulkanitpaketes entzogen und an oder nahe der Oberfl~iche angereichert. AbstractIn a geochemical study of the Proterozoic volcano-sedimentary Bergslagen ore province in central Sweden, more than 1000 eruptive rocks were analyzed for main and trace elements. The volcanic rocks form a bimodal suite dominated by rhyolites but deficient in andesites. Igneous geochemical variation bears little relevance to the occurrence and distribution of ores which mostly appear related to secondary alteration patterns. Hydrothermal metasomatic alteration occurs on a regional scale and has affected markedly more than half of the 732 analyzed, macroscopicaliy fresh, porphyritic volcanic rocks. Metasomatism produced extreme Na-and K-differentiation, and Fe-Mg-Si relationships incompatible with igneous variation patterns. Enrichment in Na and Mg, and leaching of ore-forming metals are prominent in the lower parts of the volcanic pile, whereas meta-volcanics enriched in K and volcanogenic sediments as'sociated with ores and marbles dominate the upper levels. The metasomatic alteration of the volcanic rocks and the formation of most ores are two aspects of a comprehensive process of hydrothermal convection which circulated sea water, extracted the ore-forming elements from the lower levels of the volcanic pile and enriched them at or close to the top of the volcanic sequence. R~sumEDam le cadre d'une Etude gEochimique de la province prot&ozoique volcano-s~dimentaire min~ralis& de Bergslagen (Suede centrale), plus de 1000 Echantillons de roches magmatiques ont &~ analyses (ElEments majeurs et traces). Ces roches volcaniques foi~nent une suite domin& par les rhyolites et les basaltes, tandis q...

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Section: Secondary Alterationsmentioning

confidence: 95%

Hydrothermal alteration as a control of regional geochemistry and ore formation in the central Baltic Shield

Lagerblad

Gorbatschev

1985

Geol Rundsch

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“…The rocks described in this paper belong to the UpperLeptite-H/illeflinta-Slate Group of Oen et al (1982) and were affected by low-grade greenschist facies metamorphism (Sundius, 1923), which * Present address: Technical University of Wroctaw, Institute of Inorganic Chemistry and Metallurgy of Rare Elements, 50-370 Wroctaw, Wybrze~,e Wyspiafiskiego 27, Poland.…”

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confidence: 99%

Conditions of formation of the iron-containing minerals, Hällefors silver mines, Bergslagen, Sweden

Jasiński

1986

Mineral. mag.

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ABSTRACT. The H/illefors silver deposit is regarded as a volcanogenic-exhalative iron ore deposit with dispersed amounts of Ag-Pb Zn (+Cu) which has undergone secondary remobilization leading to the concentration of sulphides and sulphosalts. Based on data from the iron oxides and sulphides, the sulphide-sulphosalt mineralization is believed to have been formed in two stages. The first is characterized by the ranges 573-473 K and 2.25 1.5 kbar, higher gradient of changes of log as2 with temperature and mostly sulphide precipitation; the second by the ranges 473-443 K, lower gradient of changes of log as2 and mainly sulphosalt deposition. Assuming the precipitation was from fluids and aqueous solutions, possible conditions of formation of some of the iron minerals have been determined.

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“…Introduction and geological setting INDIUM-bearing sphalerite associated with roquesite and In-bearing stannite or sakuraiite has previously been described from only a few localities (Kato and Shinohara, 1968;Sutherland and Boorman, 1969;Oen et al, 1980;Burke and Kieft, 1980;Shimizu et al, 1986;Johan, 1988). This paper describes the petrogenesis of a new occurrence.…”

mentioning

confidence: 99%

“…The volcano-sedimetary sequence in the Gfisborn area consists of acid metavolcanics with intercalated marbles, metacherts, metamorphosed basic lavas and a metamorphosed manganiferous iron ore horizon (Damman, 1988a), belonging to the upper leptite and slate group of the Bergslagen supracrustal series (Oen et al, 1982;Oen, 1987). During their deposition these rocks have been intruded by the Ostra Hrjden granite (Damman, 1988b (Fig.…”

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Indium-bearing chalcopyrite and sphalerite from the Gåsborn area, West Bergslagen, central Sweden

Kieft¹,

Damman²

1990

Mineral. mag.

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In the G~sborn area, West Bergslagen, central Sweden, Fe-rich, indium-bearing (0.1-2.0wt.% In) sphalerite is replaced by Fe-poor sphalerite containing minute inclusions of chalcopyrite, roquesite and an unnamed ln-Zn-rich phase. Fe-rich, In-bearing sphalerite is primary; indium occurs as a roquesite molecule in solid solution. Fe-poor sphalerite, roquesite, chalcopyrite and the unnamed In-Zn-rich phase were formed from In-bearing sphalerite by secondary processes, characterized by the so-called 'chalcopyrite disease'.

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Ore deposition in a proterozoic incipient rift zone environment: a tentative model for the Filipstad-Grythyttan-Hjulsjö region, Bergslagen, Sweden

Cited by 75 publications

References 4 publications

Hydrothermal alteration as a control of regional geochemistry and ore formation in the central Baltic Shield

Hydrothermal alteration as a control of regional geochemistry and ore formation in the central Baltic Shield

Conditions of formation of the iron-containing minerals, Hällefors silver mines, Bergslagen, Sweden

Indium-bearing chalcopyrite and sphalerite from the Gåsborn area, West Bergslagen, central Sweden

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