Linear and semi-circular features were mapped in the
volcanic terrain of the southernCoromandel Peninsula, North Island, using JERS-1 synthetic aperture
radar (SAR), Landsat-4 Thematic Mapper, and SPOT-2 multispectral satellite data,
digital elevation models, and aeromagnetic data. The mapped features typically
correspond to recognised physiographic features and are thus a useful aid to
mapping the structural trends in the region. Major linear features exhibit a
strong N-S to NNE-SSW alignment, and lesser NW-SE and NE-SW trends. All these
are superimposed on pervasive, closely spaced, NNE-SSW and NNW-SSE lineaments
present over most of the hilly parts of the map area. There are few major E-W
aligned features. Some alignment trends correspond to strike directions of veins
in the epithermal gold-silver deposits of the region, but none of the known
mineralised structures were visible on the remote sensing data.

The
volcanic rocks are Late Cenozoic in age and include a variety of rock types:
andesite and dacite flows, domes and tuff breccias, rhyolite domes, tuffs and
tephra, lacustrine siltstones, and ignimbrites. Mapping of different textures in
the SAR image failed to provide additional information on rock types to that
derived from the Landsat and SPOT images. A simple discrimination of rock units
based on radar texture is apparently prevented by the complex volcanic geology,
superimposed hydrothermal alteration, and long period of
erosion.