Inferring the Orientations of the Foliation and Lineation Defined by Quartz c -Axis Fabrics: Methods and Applications.

In this manuscript, I introduce a convenient method to convert the Euler angles (complete crystal orientations) obtained with EBSD (electron back-scattered diffraction) to the azimuth and inclination angle of crystallographic axes to reconstruct the pole figures. This method, which is subsequently coupled with the rotation of the pole figures, is particularly useful for the analyses of quartz c-axis fabrics in the deformed rocks, where the foliation and/or lineation is not clear or unknown. Although we arbitrarily choose the sample coordinates (Xs-Ys-Zs) in such cases, it is often possible that we can rotate the quartz c-axis pole figures so that they will exhibit a well-defined intrinsic symmetry in the rotated sample frame. The rotated XsYs-plane and Xs-direction can be now called the foliation and lineation, respectively, inversely defined by the quartz c-axis fabrics. On the other hand, the foliation and lineation clearly defined by the shape-preferred orientations (SPOs) of platy or columnar minerals can be oblique to those defined by the quartz c-axis fabrics. In this case, the former foliation and lineation could represent the total strain, while the latter ones could represent the last incremental strain, indicating triclinic deformation symmetry (e.g., triclinic transpression). [ABSTRACT FROM AUTHOR]