Javascript är avstängt eller blockerat i din webbläsare. Detta kan leda till att vissa delar av vår webbplats inte fungerar som de ska. Sätt på javascript för optimal funktionalitet och utseende.

Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Lotta_2018-10

Charlotte Möller

Professor

Lotta_2018-10

Petrology and ion microprobe U-Pb chronology applied to a metabasic intrusion in southern Sweden: A study on zircon formation during metamorphism and deformation

Författare

  • Pia Söderlund
  • Ulf Söderlund
  • Charlotte Möller
  • Roland Gorbatschev
  • Agnes Rodhe

Summary, in English

The Aker metabasite occupies a key position in a major tectonic lineament in southernmost Sweden, the Protogine Zone, which coincides closely with the eastern boundary of the late Mesoproterozoic Sveconorwegian orogen of southwest Scandinavia. Metamorphic reactions, associated with the transformation from isotropic gabbro to foliated garnet amphibolite, were identified from disequilibrium textures of which some involved release of zirconium (Zr) and growth of metamorphic zircon. Ion microprobe dating of igneous zircon gave 1562 +/- 6 Ma, whereas metamorphic zircons yielded ages of 1437 +/- 21, 1217 +/- 75, and 1006 +/- 68 Ma. The presence of baddeleyite pseudomorphs made up of saccharoidal zircon and a higher abundance of older rather than younger metamorphic zircons suggest redistribution of Zr into new zircon, first by the breakdown of baddeleyite (ZrO2) and later by the consumption of igneous phases containing trace amounts of Zr. Several generations of metamorphic zircon and the presence of 1.56 and 1.22 Ga mafic intrusions along the Protogine Zone call for a complex tectonic history probably reaching back to at least similar to1.56 Ga. Growth of metamorphic zircon at similar to1.44 Ga may relate to a regional, compressional event. The WNW trending deformational structures on both sides of the Protogine Zone may possibly relate to that event. The similar to1.22 Ga metamorphic zircons are coeval with the emplacement of numerous granitic, syenitic, and mafic intrusions along and parallel to the Protogine Zone. The age around 1.0 Ga, finally, marks Sveconorwegian metamorphism for which thermobarometry of the Aker garnet-amphibolite suggests 1000-1200 MPa at 600degreesC-630degreesC. Thereafter, significant relative uplift of the rocks to the west of the Protogine Zone occurred on nearly vertical, north-south trending deformation zones.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2004

Språk

Engelska

Publikation/Tidskrift/Serie

Tectonics

Volym

23

Issue

5

Dokumenttyp

Artikel i tidskrift

Förlag

American Geophysical Union (AGU)

Ämne

  • Geology

Nyckelord

  • U-Pb geochronology
  • Protogine Zone
  • metamorphism

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0278-7407