Tonalite-hosted early Proterozoic gold deposit at Osikonmaki, southeastern Finland

Kontoniemi, Olavi; Ekdahl, E.

doi:10.17741/bgsf/62.1.003

Cited by 3 publications

(3 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The increasing economic importance of gold during the last decade led to the discovery of a number of auriferous prospects in the Skellefte, Pohjanmaa and Rantasalmi districts during the 1980s (L6fgren 1987;Weihed and Bergstr6m 1988;Mfikel/i et al 1988 a,b;Kontoniemi and Ekdahl 1990). These prospecting efforts have so far resulted in the first two mines opened solely for gold production in the Skellefte District: Bj6rkdal in 1988 and/~kerberg in 1990.…”

Section: Gold Depositsmentioning

confidence: 99%

“…Tallberg and Kopsa (Gafil and Isohanni 1979;Weihed et al 1987), epigenetic gold lode deposits in a number of rock types, e.g. Middagsberget, Bj6rkdal, Grundfors, Laivakangas, Kangaskylfi and Osikonm/iki (Markkula 1988;M/ikel/i et al 1988 a,b;Weihed and Bergstr6m 1988;Kontoniemi and Ekdahl 1990;Bergman 1992), and epigenetic gold lode deposits in volcanogenic massive sulphide systems, e.g. Boliden (Bergman et al 1989).…”

Section: Gold Depositsmentioning

confidence: 99%

See 1 more Smart Citation

Source of metals and age constraints for epigenetic gold deposits in the Skellefte and Pohjanmaa districts, central part of the Fennoscandian Shield

et al. 1993

View full text Add to dashboard Cite

Abstract. The lead isotopic compositions of galena in Early Proterozoic gold deposits have been determined for three districts in northern Sweden and central Finland. The deposits are hosted by a variety of ~ 1870-1890 Ma Svecofennian host rocks including the volcanosedimentary succession within the Skellefte District island arc in Sweden as well as I-type tonalites at J6rn (Sweden) and Pohjanmaa (Finland). The deposits are epigenetic in relation to these Svecofennian rocks and are part of a goldbearing metallogenetic belt, which can be followed for 600 km parallel to the southwestern margin of the Archaean Domain. In spite of these epigenetic relationships, the lead isotopic data indicate that the deposits are not dramatically younger than the ~1870-1890 Ma Svecofennian host rocks (probably not exceeding 10-20 million years). Two principal lead sources were activated when the gold deposits were formed.-The most significant source is represented by the I-type tonalites, which constitute a relatively primitive (/~ = 9.3) and widely distributed source in the entire metaUogenic belt. In addition, the volcanic components in the westernmost part of the Skellefte District constitute an extremely primitive (~ < 9.0) source, which only locally was an important contributor to the epigenetic deposits in this metallogenetic belt. The significantly different lead isotopic composition estimated for these sources indicates that the volcanic rocks in the western part of the SkeUefte District were not comagmatic with the I-type tonalites recognized at J6rn and central Finland.partly related to volcanogenic massive sulphide deposits of the Skellefte type, partly related to synkinematic intrusions of the J6rn type and partly related to major shear zone structures. This complex metallogenetic province can be followed over a length of about 600 km and includes the Skellefte mining district in northern Sweden, and the 'main sulphide belt' of central Finland (Fig. 1). Volcanogenic massive sulphide deposits (VMS) and Niores were until recently the only ore types which were mined in this province, but during the last decade, increasing interest has also been focused on gold lode deposits and two gold mines have come into production since 1988.The origin of the massive sulphide deposits and the Ni-ores has been discussed in a number of papers (see e.g.

show abstract

Section: Gold Depositsmentioning

confidence: 99%

Section: Gold Depositsmentioning

confidence: 99%

Source of metals and age constraints for epigenetic gold deposits in the Skellefte and Pohjanmaa districts, central part of the Fennoscandian Shield

et al. 1993

View full text Add to dashboard Cite

show abstract

“…The gold mineralization in the nearby tonalite-hosted Osikonmfiki prospect (Kontoniemi and Ekdahl 1990;Kontoniemi et al 1991), is associated with a E-W striking shear zone (see Fig. 1) and the sheared host rock is hydrothermally altered (silification and potassic alteration).…”

Section: The Piril/i Gold Depositmentioning

confidence: 98%

Fluid inclusion geochemistry of the early Proterozoic Piril� gold deposit in Rantasalmi, Southeastern Finland

Poutiainen

1993

Mineral. Deposita

View full text Add to dashboard Cite

Abstract. The small Pirilfi gold deposit, which is located in the southeastern part of the Svecofennian complex near the Archean/Proterozoic boundary, is hosted by quartz veins and lenses occurring in mica schist. The rocks of the area were metamorphosed under conditions of amphibolite facies. Gold is invariably associated with sulphides. Microthermometry of fluid inclusions in quartz indicates four types of inclusions: (1) weakly saline H20-CO2 ( < 4.0 eq.wt % NaCI) with small amounts of CH4 ( < 10 mole % CH4); (2) CO2 ( < 10 mole % CH4); (3) CH4; and (4) H20 ( < 25 eq.wt % NaC1) with less than 0.85 mole % CO 2 in the vapour phase. Texturally these inclusion types are classified as primary (HEO-CO2) and secondary (H20, CO2 and CH4). Leachate analysis shows that, in addition to Na, the aqueous fluids contain Ca and Fe with minor amounts of K and Mg. The primary H20-CO z and the secondary HzO inclusions contain sulphide and unidentified opaque grains, respectively. The secondary CH 4 inclusions are often associated with short trails of arsenopyrite grains. Fluid inclusion and geological data suggest ore mineral mobilization, crystallization of host quartz, and deposition of sulphides controlled by the D 2 and D 3 structures in the presence of a HzO-CO z fluid mainly during the plastic D 3 deformation and during the amphibolite facies metamorphism (i.e. 3.4 kbars/540-670~ During ductile-brittle deformation (probably D4), precipitation of tectonic remobilized gold from sulphides in fractures occurred in the presence of CH 4 and HzO fluids at lowered temperature (< 440~ and pressure (< 2 kbars).The Pirii/i gold deposit is a base metal-bearing mineralization hosted by quartz lenses and veins in an early Proterozoic Svecokarelian complex in Rantasalmi, southeastern Finland. The deposit lies within the RaaheLadoga zone (Kahma 1973(Kahma , 1978, which is a boundary between the Archean and Proterozoic crust in central and eastern Finland (Fig. 1). The estimated ore reserves of the deposit are 0.15 Mt with an average grade of 8 g/t Au and 30 g/t Ag (Makkonen and Ekdahl 1988). The rocks of the Pirilfi area have suffered a polyphase deformation and an amphibolite facies metamorphism (Kilpel/iinen 1988;Korsman 1977). A fluid inclusion study was undertaken to obtain information on the temperature and composition of the fluids and to impose further constraints on the origin of the deposit. On the regional scale, fluids associated with the progressive stage of metamorphism and deformation were studied by Poutiainen (1990).

show abstract

Metallogeny of gold in the Fennoscandian Shield

Gaál

Sundblad

1990

Mineral. Deposita

View full text Add to dashboard Cite

Tonalite-hosted early Proterozoic gold deposit at Osikonmaki, southeastern Finland

Cited by 3 publications

References 4 publications

Source of metals and age constraints for epigenetic gold deposits in the Skellefte and Pohjanmaa districts, central part of the Fennoscandian Shield

Source of metals and age constraints for epigenetic gold deposits in the Skellefte and Pohjanmaa districts, central part of the Fennoscandian Shield

Fluid inclusion geochemistry of the early Proterozoic Piril� gold deposit in Rantasalmi, Southeastern Finland

Metallogeny of gold in the Fennoscandian Shield

Contact Info

Product

Resources

About