U‐Pb datings of the Hedesunda and Åkersberga granites of south‐central Sweden

Abstract

U‐Pb datings have been performed on two samples of por‐phyritic granites in eastern south‐central Sweden; the Åkersberga and Hedesunda granites. The Åkersberga granite belongs to early‐orogenic Svecofennian plutonics, and its crystallisation age is 1875±6 Ma, which slightly younger than the hitherto obtained ages of early Svecofennian rocks in this region. This granite is contemporaneous with plutonics and volcanics in southwestern Finland and northern Sweden. The crystallisation age of the Hedesunda granite is 1782+5 Ma, thus representing a late‐orogenic intrusion. The isotopic, chemical, and petrographical data show similarities to other late‐Svecofennian granites.

Persson, L. & Persson, P.‐O., 1997: U‐Pb datings of the Hedesunda and Åkersberga granites of south‐central Sweden. GFF, Vol. 119 (Pt. 2, June), pp. 91–95. Stockholm. ISSN 1103–5897.

Keywords:

• U‐Pb
• radiometric dating
• zircon
• titanite
• granite
• granitoid
• syenite
• early orogenic
• late orogenic
• Svecofennian
• TIB
• Åkersberga
• Hedesunda
• Sweden