Fabric orientation of olivine porphyroblasts in the Ultramafitite Complex of Åheim, Sunnmöre, western Norway

Summary The lattice orientation of olivine porphyroblasts in dunites of the Åheim Ultramafic Complex, western Norway, shows a principal -direction parallel to lineation in the host rock, corresponding to the tectonic B-axis. The other optical axes and form a girdle in the tectonic ac-plane with certain maximas. This orientation is caused by an earlier stress pattern. ThePT-conditions of this deformation may be explained by experimental results of other authors.Small recrystallized olivine inclusions in the blasts tend toward an -orientation perpendicular to S; rotates into the direction of lineartion. The same orientation occurs predominatly in the olivine rocks of the complex, which also have recrystallized during a younger retrograde metamorphism under the conditions of the chlorite amphibole peridotite facies.