Scattered data points from anorthosite-suite rocks of the Gneiss Region of western Norway indicate a minimum age of 1,511 ± 64 m.y. The scatter is believed to be related to retrograde metamorphism of > 1,511 m.y. old original granulite-facies rocks, formation of mica foliation, and regional EW folding during a Sveconorwegian (Grenville) regeneration event previously detined by 40Ar/ 39Ar dating from the same suite. Anorthosite-suite rocks of the Gneiss Region can be related to the 1,600 ± 200 m.y. old belt of anorthosite and rapakivi massifs of the north Atlantic shield.