SIMS U-Pb zircon geochronology at the Kuså Ni-Cu deposit, south-central Sweden

Abstract

The Kuså orthomagmatic Ni-Cu sulphide deposit is situated c. 13 km west of Falun in Bergslagen, south-central Sweden. Ion probe data on zircon from the mafic to ultra-mafic host rocks yield a ²⁰⁷Pb/²⁰⁶Pb weighted average age of 1798 ± 4 Ma, suggesting a genetic connection to intrusive activity forming the Transscandinavian Igneous Belt (TIB-1 phase). TIB-1 ages have recently been reported also for the Kleva deposit of similar type in Southern Sweden. The presence of these two occurrences suggests prospectivity potential for Ni-Cu mineralisation in mafic to ultramafic members of the areally extensive TIB.

Keywords:

• Kuså Ni-Cu deposit
• Bergslagen
• Transscandinavian Igneous Belt
• SIMS U–Pb geochronology
• zircon

Acknowledgements

Martin Whitehouse, Lev Ilyinsky and Kerstin Lindén (NordSIM laboratory) are thanked for their technical assistance and allocating additional time for SIMS analysis connected to this study. This is NordSIM publication no. 512. An anonymous reviewer and editor C. Skovsted are thanked for comments on the original text.