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

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Authors:Sundblad, K.; Weihed, P.; Billstrom, K.; Markkula, H.; Makela, M.
Author Affiliations:Primary:
Stockholm University, Stockholm, Sweden
Geological Survey of Sweden, Sweden
Swedish Museum of Natural History, Sweden
Swedish Geological Company, Sweden
University of Helsinki, Finland
Volume Title:Mineralium Deposita
Source:Mineralium Deposita, 28(3), p.181-190. Publisher: Springer-Verlag, Berlin, Federal Republic of Germany. ISSN: 0026-4598
Publication Date:1993
Note:In English. 59 refs.; illus., incl. 2 tables, geol. sketch maps
Summary:The Pb isotopic compositions of galena in early Proterozoic Au deposits have been determined for three districts in N Sweden and central Finland. The deposits are hosted by a variety of approx 1870-1890 m.y. old Svecofennian rocks including the volcano- sedimentary succession in the Skellefte district island arc (Sweden) and I-type tonalites at Jorn (Sweden) and Pohjanmaa (Finland). The deposits are epigenetic in relation to these Svecofennian rocks and are part of an Au-bearing metallogenetic belt. In spite of the epigenetic relationships the Pb isotope data indicate that the deposits are not much younger than the host rocks (probably not > 10-20 m.y.). Two main sources of Pb were activated when the Au deposits formed, the most significant of which is represented by the I-type tonalites, which constitute a relatively primitive and widely distributed source in the belt. In addition, the volcanic components in the W part of the Skellefte district constitute a very primitive source, which only locally was an important contributor to the epigenetic deposits. The significantly different Pb isotope compositions estimated for these sources indicate that the volcanic rocks in the W part of the Skellefte district were not co-magmatic with the I-type tonalites recognized at Jorn and central Finland. [R.E.S.]
Subjects:Diorites; Epigene processes; Gold ores; Host rocks; Igneous rocks; Isotopes; Lead; Massive deposits; Massive sulfide deposits; Metal ores; Metals; Nickel ores; Paleoproterozoic; Pb-206/Pb-204; Pb-207/Pb-204; Pb-208/Pb-204; Plutonic rocks; Precambrian; Proterozoic; Radioactive isotopes; Stable isotopes; Svecofennian; Tonalite; Upper Precambrian; Volcanism; Europe; Fennoscandia; Fennoscandian Shield; Scandinavia; Skellefte mining district; Sweden; Western Europe; Pohjanmaa mining district
Abstract Numbers:94M/1934
Record ID:1995038368
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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