Preferred Orientations of Mica Bearing Rocks Described by Texture Components

Abstract

Up to now Texture investigations of phyllosilicates were restricted to pole density measurements of the (001) basal plane. Because of the tabular grain shape parallel to the basal plane an axial symmetry of the texture is assumed usually. This assumption was proved for four mica bearing samples by calculating the ODF from neutron diffraction data. Beside the mica-texture the textures of the other major fractions like quartz and feldspar were determined to detect correlation between them. The textures are explained by components. Each component is characterised by a preferred orientation or fibre axis, a corresponding spreading and an intensity Iʿ describing the volume fraction of all crystallites belonging to the component. The presented component method can be applied to any crystal symmetry and to polyphase materials with overlapped pole figures.