The Ulvo Gabbro Complex of the 1.27-1.25 Ga Central Scandinavian Dolerite Group (CSDG): Intrusive age, magmatic setting and metamorphic history

Summary, in English

The Ulvo Gabbro Complex (UGC) belongs to the 1.27-1.25 Ga Central Scandinavian Dolerite Group (CSDG), which manifests a major event of intra-cratonic mafic magmatism possibly related to break-up between Laurentia and Baltica. Lopolithic, layered intrusions of the UGC outcrop in east central Sweden and west central Finland. Fresh baddeleyite grains in a pegmatoidal gabbro were dated by the TIMS U-Pb method. The age of 1256.2 +/- 1.1 Ma is interpreted to date crystallisation of the UGC, and is consistent with the age of other mafic intrusions of the CSDG in Vasterbotten and south-western Finland. Previously reported K-Ar biotite data confirm that the UGC was not heated above the blocking temperature for Ar diffusion in biotite (similar to 250 degrees C) after similar to 1.2 Ga. This suggests that UGC was virtually unaffected by later geological events and that magmatic textures and mineralogy have not been modified after solidification.

• Författare: KJ Hogmalm; Ulf Söderlund; SA Larson; WP Meurer; FA Hellstrom; DT Claeson
• Avdelning/ar: Berggrundsgeologi
• Publiceringsår: 2006
• Språk: Engelska
• Sidor: 1-6
• Publikation/Tidskrift/Serie: GFF
• Volym: 128
• Länkar: http://www.gff-online.se/site/article.asp?articleID=850
• Dokumenttyp: Artikel i tidskrift
• Förlag: Taylor & Francis
• Ämne: Geology
• Nyckelord: intrusion; layered; U-Pb; CSDG; baddeleyite; Ulvo Gabbro Complex; ulvospinel
• Aktiv: Published
• ISBN/ISSN/Övrigt: ISSN: 2000-0863