Author(s): M. S. Rattenbury et al

Geology

This map and text illustrate the geology of the Kaikoura area, extending east from Murchison to southern Marlborough, and south to Waikari in north Canterbury. Onshore geology is mapped at a scale of 1:250 000 while offshore the bathymetry, thick Quaternary sedimentary deposits and major structural elements are shown. The accompanying text summarises the geology and tectonic development, as well as the geological hazards and the economic and engineering geology of the map area. The map area is mostly underlain by Mesozoic greywacke rocks of the Torlesse terrane, except in the northwest where narrow fault-bounded remnants of the Buller, Takaka, Brook Street, Murihiku, Dun Mountain-Maitai and Caples terranes occur, as well as the Median Batholith and other granitic rocks. Discontinuously preserved late Early Cretaceous to Pliocene, predominantly marine sedimentary and volcanogenic rocks occur in the northwest, the east and the south of the map area. Quaternary terrestrial sediments are widespread on land, including till, loess, scree, landslide, alluvial fan and alluvial terrace deposits. Numerous active faults of the Marlborough Fault System transect the map area, marking the plate boundary zone between the Pacific and Australian tectonic plates. Several of these faults have moved in historic times contributing to the region