No abstract

Initial results from a seismic experiment in the central South Island, New Zealand, have imaged a 40 ± 5°s outheast-dipping zone at a depth of c. 22 km beneath the Mt Cook village. It is speculated that this reflector represents the down-dip extension of the Alpine Fault Zone.

3D modelling of satellite gravity data covering the offshore area west of New Zealand has been used to predict the depth to the seafloor, basement, and Moho. The models assume constant densities for each layer, with no lateral changes of rock properties. The modelling was done on a 2.5 km grid. Depths to the seafloor, basement, and Moho were interpreted from seismic data or taken from published sources, and were used to constrain the solutions.

65Total force magnetic anomalies at a height of 3 '05 km over southern New Zealand are presented. Over the Haast Schist Group magnetic relief is low with the

Two-dimensional and three-dimensional gravity models of the Mesozoic basement topography in the Wairarapa show that the major feature is the Wairarapa Trough, aligned SSW-NNE through the area. The Trough has two arms, one north of Eketahuna and the other south of Carterton. All three features are fault-angle depressions, bounded to the west by the West Wairarapa, Wellington, and Dry River Faults, respectively, and reaching their greatest depths at these faults. A structural contour map of the Mesozoic surface in the Wairarapa shows that the basement is covered by more than 3000 m of Cenozoic material. The West Wairarapa Fault is shown to be reverse in the south, with a dip as low as 15°. The other faults are apparently near-vertical.