Precambrian geodynamics and ore formation: The Fennoscandian Shield

• Published in: Ore Geology Reviews
• Main Authors: Weihed, Pär, Arndt, Nicholas, Billström, Kjell, Duchesne, Jean-Clair, Eilu, Pasi, Martinsson, Olof, Papunen, Heikki, Lahtinen, Raimo
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science Bv 2005
• Subjects: Palaeoproterozoic; Fennoscandian Shield; VMS; orogenic gold; iron oxide-copper-gold (IOCG); anorthosite; titanium deposit; Engineering; computing & technology; Geological; petroleum & mining engineering; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Ingénierie; informatique & technologie; Géologie; ingénierie du pétrole & des mines; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Fennoscandian
• Online Access: https://orbi.uliege.be/handle/2268/1891; https://orbi.uliege.be/bitstream/2268/1891/1/Weiheid.pdf; https://doi.org/10.1016/j.oregeorev.2005.07.008

peer reviewed Compared with present-day global plate tectonics, Archaean and Palaeoproterozoic plate tectonics may have involved faster moving, hotter plates that accumulated less sediment and contained a thinner section of lithospheric mantle. This scenario also fits with the complex geodynamic evolution of the Fennoscandian Shield from 2.06 to 1.78 Ga when rapid accretion of island arcs and several microcontinent-continent collisions in a complex array of orogens was manifested in short-lived but intense orogenies involving voluminous magmatism. With a few exceptions, all major ore deposits formed in specific tectonic settings between 2.06 and 1.78 Ga and thus a strong geodynamic control oil ore deposit formation is suggested. All orogenic gold deposits formed syn- to post-peak metamorphism and their timing reflects the orogenic younging of the shield towards the SW and west. Most orogenic gold deposits formed during periods of crustal shortening with peaks at 2.72 to 2.67, 1.90 to 1.86 and 1.85 to 1.79 Ga. The ca. 2.5 to 2.4 Ga Ni-Cu PGE deposits formed both as part of layered igneous complexes and associated with mafic volcanism, in basins formed during rifling of the Archaean craton at ca. 2.5 to 2.4 Ga. Svecokarelian ca. 1.89 to 1.88 Ga Ni-Cu deposits are related to mafic-ultramafic rocks intruded along linear belts at the accretionary margins of microcratons. All major VMS deposits in the Fennoscandian Shield formed between 1.97 and 1.88 Ga, in extensional settings, prior to basin inversion and accretion. The oldest "Cyprus-type" deposits were obducted onto the Archaean continent during the onset of convergence. The Pyhasalmi VMS deposits formed at 1.93 to 1.91 Ga in primitive, bimodal arc complexes during extension of the arc. In contrast, the Skellefte VMS deposits are 20 to 30 million years younger and formed in a strongly extensional intra-arc region that developed on continental or mature arc crust. Deposits in the Bergslagen-Uusimaa belt are similar in age to the Skellefte deposits and formed in a ...