Basic dykes and dyke swarms in central and northern Sweden and the plate tectonic evolution of Fennoscandia: palaeomagnetic and Ar39/Ar40 studies
2005 (English)In: "Dyke swarms - time markers of crustal evolution": Fifth International Dyke Conference, Pohtimolampi Wilderness Hotel, Polar Circle, Rovaniemi, Finland, 31 June - 3 August 2005 ; abstracts and programme / [ed] Jouni Vuollo; Satu Mertanen, Espoo: Geological Survey of Finland , 2005, 11- p.Conference paper, Meeting abstract (Other academic)
Palaeomagnetic and Ar39/Ar40 studies have been performed on basic dykes and dyke swarms in central and northern Sweden. At least five different generations of dykes have been defined and will be discussed in a plate tectonic context. Reliable palaeomagnetic data have been obtained from a big gabbro diabase and a geographically related dyke swarm in the northern part of Sweden from which poles similar to those calculated from Svecofennian gabbros (ca 1.86 Ga) are defined. In another swarm of palaeomagnetically similar age, just north of the Skellefte district, partially remagnetized dykes indicate a possible Subjotnian or Caledonian regional remagnetization. The dykes are younger when moving towards the south and in the central part there is a significant dyke swarm with at least two generations of dykes (ca. 1.7 and 1.6 Ga, respectively), one of which is related with rapakivi magmatism. Palaeomagnetic and anisotropy of magnetic susceptibility (AMS) data from the huge ca 1.25 Ga sill complexes in central Sweden and western Finland and from basic intrusions in Greenland suggest that Baltica and Laurentia were joined at that time. The similar stress field as indicated by the AMS data and the tensional regime reflected by the sill complexes is interpreted related to the break up of Baltica from Laurentia. New data from ca 1.1 Ga dykes in central Sweden confirms a clockwise rotation of Fennoscandia between 1.25 and 1.1 Ga, a rotation that is not seen for Laurentia.
Place, publisher, year, edition, pages
Espoo: Geological Survey of Finland , 2005. 11- p.
Research subject Applied Geophysics
IdentifiersURN: urn:nbn:se:ltu:diva-38691Local ID: d261e3a0-6895-11de-9f57-000ea68e967bISBN: 951-690-926-4 (print)OAI: oai:DiVA.org:ltu-38691DiVA: diva2:1012192
International Dyke Conference : 31/07/2005 - 03/08/2005
Godkänd; 2005; 20090704 (ysko)2016-10-032016-10-03Bibliographically approved