Minor element chemistry of hemo-ilmenite and magnetite in cumulate rocks from the Sokndal Region, South Rogaland, Norway

Chemistry of the Fe-Ti oxide minerals in the Bjerkreim-Sokndal layered intr usion and in the Tellnes Ilmenite Norite suggests some parallels in magmati c evolution and resultant petrography. Early ilmenites have high ratios of Mg/(Mg + Fe) and Cr/R3+ and intermediate to low V/R3+, and abundant fine he matite exsolution lamellae, in which Cr, V, and Al are concentrated. Magmat ic evolution results in lower Mg/(Mg + Fe), lower Cr/R3+ and higher V/R3+. With magma saturation with magnetite, V/R3+ falls both in ilmenite of rapid ly decreasing abundance, and in magnetite, but there is an increase in Mg/( Mg + Fe) of ilmenite, probably, due to late ion exchange with much more abu ndant magnetite. Aside from implications related to magma evolution, these results give information concerning fractionation of elements between the r hombohedral and cubic oxide series, and especially between the ilmenite hos ts and their contained hematite exsolution lamellae.