A study of fold styles, their associations and symmetry relationships, from Sørøy, North Norway

The Eo-Cambrian rocks of Sørøy have undergone repeated phases of falding and metamorphism during the Caledonian orogeny. As the result of the second phase of falding large open symmetrical to asymmetrical folds were formed in the Sandøfjord area, deformation also taking place on complementary shears with the production of minor folds ha ving both conjugate and non-conjugate (asymmetric) styles. The trends of these minor folds fall into two sets according to the attitude of the axial planes. Considering the complementary shears alone the symmetry of the movements is orthorhombic, but ha ving regard to the overall geometry of the fold patterns a lower symmetry obtains. The relationship of the minor folds to the major structures is discussed and also the effects of differing lithologies on fold trends and styles.