Hanski, E (2015) Synthesis of the Geological Evolution and Metallogeny of Finland. In: Mineral Deposits of Finland. Elsevier, pp. 39-71. ISBN 978-0-12-410438-9
Full text not available from this repository.Abstract
The bulk of the Finnish bedrock evolved during four time periods, encompassing (1) the 3200–2700 Ma Archean cratonic basement, (2) its Paleoproterozoic, 2500–1920 Ma volcano-sedimentary cover and related intrusive magmatism, (3) the 1930–1770 Ma Svecofennian composite orogen, and (4) the 1640–1460 Ma rapakivi magmatism. Each of these periods displays its own metallogenic characteristics. In the Archean, orogenic gold and epithermal Ag-Au, komatiite-related Ni-Cu, and porphyry Mo have exceeded or approached the economic threshold, and a single carbonatite body is exploited for apatite. The most important deposit type in the Archean part of the Fennoscandian Shield is banded iron formation, but the major deposits occur outside Finland. Incipient rifting of the Archean supercontinent was accompanied by emplacement of large 2440 Ma mafic–ultramafic intrusions hosting stratiform Cr and Fe-Ti-V deposits, PGE-enriched reefs, and Ni-Cu-PGE contact and offset mineralization. At a later stage, when deep-water, pelitic continental margin sediments were deposited, intruding mafic magma produced Ni-Cu deposits (2050 Ma) in relatively small magma chambers. In addition, sedimentary black shale-hosted Ni-Zn-Cu deposits were formed. Continental breakup resulted in the formation of new oceanic crust, and Outokumpu-type volcanic massive sulfide (VMS) Cu-Co-Ni deposits were generated by hydrothermal processes affecting exposed ultramafic mantle rocks on the seafloor. The most prolific ore-forming stage ensued during the assembly of the Svecofennian orogen, composed of a collage of island-arc terranes and microcontinents. Many ore types typical of convergent plate boundaries were formed, including prominent VMS Pb-Zn, ultramafic-hosted Ni-Cu, and orogenic gold deposits. In addition, porphyry Cu and Mo, epithermal Au-Ag, iron oxide-copper-gold (IOCG) and pegmatite-hosted Li styles of mineralization are locally significant. So far, the anorogenic rapakivi magmatism has not provided exploitable metal occurrences, but shows potential for several high-tech metal deposits. Diamondiferous kimberlite pipes, approximately 600 Ma and 1200 Ma in age, have been found in eastern Finland, and the phosphorous and high-tech metal resources of a large Devonian carbonatite are currently assessed.
| Item Type: | Book Section |
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| Uncontrolled Keywords: | metallogenyore depositsgeological evolutionPrecambrianFennoscandian ShieldFinland |
| Subjects: | Methodology > Other-additional study Region > Finland > Pyhäjärvi Inducing technology > Underground mining |
| Project: | EPOS-IP > PYHASALMI MINE: in situ underground laboratory |