Geochemistry of the Bjerkreim – Sokndal layered intrusion

Prof. Jean-Clair Duchesne, Univ. Liége, Belgium

Investigation on the formation of cumulate rocks in layered series through a geochemical approach (major and trace elements) with particular reference to the sorting mechanism and influence of intercumulate liquids. The relationships between variations in Fe-Ti oxide minerals texture and chemistry and the magmatic evolution and stratigraphic position in the intrusion will be particularly studied. In this connection, partitioning of trace elements between the various cumulate minerals in typical rock types will be determined in order to assess a set of the mineral/melt distribution coefficients. The use of Laser Ablation techniques (LA-ICP-MS) will permit to account for trace mineral contamination in the separation process.

Completion of the geochemical characterisation of several types of charnockite rocks which are derived from residual liquids associated with the Bjerkreim – Sokndal intrusion or with jotunitic dykes. Ion-probe U-Pb dating of the cores and rims of zoned zircons from these rocks to help sorting out source rock heritage, wall rock contamination and magma mixing in the granitoid formation.