Notes on the structure of greywackes and argillites at Tawharanui Peninsula, Auckland

Summary Statistical analysis of bedding surfaces, shear surfaces and joint planes indicates that a basement series of greywackes and argillites has undergone at least two phases of folding of contrasting styles. It is suggested that an earlier phase of large‐scale flexural slip‐folding about a N.N.W. axis, β, along with attendant overturning, was followed by a phase of folding parallel to B induced by movement on oblique shear surfaces; the B axes are marked by corrugations. An anticlockwise rotation of approximately 30°, bringing β to the present N.W. trend during overturning, is suggested to explain its relation to the N.N.W. trend of B.