Structural features of the Alpine Schists of the Franz Josef — Fox Glacier Region

Abstract

Fold axes in the steeply dipping greywackes and schists to the west of the Alpine divide may be located by determinations of the superposition of beds made from observations of: (1) graded bedding; (2) intraformational structures; (3) contemporaneous deformation structures; (4) crossbedding; (5) slip folds; (6) drag folds and minor folds: (7) axial plane cleavages, joints and quartz veins; and (R) feather ioints. Both joints and fault patterns have been demonstrated to be statistically related to the fold axes by means of equal area projections. The fold axes trend between 40° and 50° and locally diverge southward from the Alpine fault whose strike is 58°. Petrofabric study of calcite optic axes from marble shows a preferral orientation nearly normal to the Alpine fault. The direction of maximum principal stress during deformation inferred from fold axes and Joints is about 310° , while that inferred from the attitude of the Alpine Fault and the calcite orientation is about 327°, but it is not thought that the difference is significant,