A refined U-Pb age for the Stockholm granite at Frescati, east-central Sweden. (2nd January 2019)

• Record Type: Journal Article
• Authors: Johansson, Åke
• Is Part Of: GFF. Volume 141:Number 1(2019)
• Page Start: 40
• Page End: 47
• Publication Date: 2019-01-02
• Subjects: Stockholm granite -- late-orogenic granites -- granite-pegmatite (GP) suite -- Svecofennian province; Geology -- Scandinavia -- Periodicals; Geology -- Periodicals; 554.8
• DOI: 10.1080/11035897.2018.1555186
• Languages: English
• ISSNs: 1103-5897

Abstract

ABSTRACT: A sample of fine-grained grey Stockholm granite from the Frescati area just north of central Stockholm, east-central Sweden, earlier dated to 1803 +23 /−19 Ma by the U-Pb zircon method using TIMS on multigrain fractions, has been reanalyzed using the Nordsim ion microprobe. The new age obtained, 1792±4 Ma, is more precise, and replaces the earlier highly discordant date. It agrees well with other ages for the formation of the Stockholm-type granites and related pegmatites, indicating an age of around 1.79 Ga for this late-orogenic Svecofennian granite magmatism. The Stockholm granite thus formed toward the end of the 1.83–1.79 Ga late Svecofennian metamorphic phase, and crosscuts earlier formed migmatitic gneiss structures in a brittle manner at the present-day level of exposure.