ORIENTATION DISTRIBUTION FUNCTION OF BIOTITE PLATELETS BASED ON OPTICAL, THIN SECTIONS AND $\mu$-CT IMAGE ANALYSIS IN AN OUTOKUMPU (FINLAND) BIOTITE GNEISS: COMPARISON WITH NEUTRON DIFFRACTION TEXTURE ANALYSIS

Abstract

The results of the neutron diffraction investigation were compared with similar results obtained by analysing more $\mu$-CT, high resolution photographic and thin section images of a cylindrical sample of the textured Outokumpu (Finland) biotite gneiss. All data were interpreted by means of corresponding orientation distribution function (ODF). Both Rayleigh $R$ test of uniformity and Rao''s $U$ test for homogeneity of the corresponding ODF confirmed the existence of a real anisotropic distribution of mineralogical phases within investigated specimens. Together with the neutron diffraction pole figures, ODF, unambiguously proved the existence of a lattice as well as of the shape preferred orientations of the mineralogical components of the complex Outokumpu gneiss.