On the formation of a carbonate-bearing ultrabasic rock at Kviteberg, Lyngen, northern Norway.

Abstract

An area of crystalline dolomite, schists, and gneiss including an ultrabasic body at 60 degrees 35' N and 20 degrees 18' E is described petrographically and structurally. The ultrabasic rock contains enstatite, olivine, and dolomite as essential minerals. Overfolding and thrusting due to pressure from NW part of the Caldonian orogeny, are described. Two modes of formation of the ultrabasic: 1, injection of an ultrabasic magma which crystallized in place;and 2, by metamorphic differentiation, are discussed theoretically and then evaluated in the light of the field relationships and structural and petrographical observations. Because the theory of the formation by metamorphic differentiation accords with all of the observations while the magmatic mode of origin does not, the conclusion is drawn that the ultrabasic rock at Kviteberg is a metamorphic differentiate.