Johnston, M.R. 1996 Geology of the D'Urville area : sheets P26AC and part P25, scale 1:50 000 (flat map). Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences geological map 16 52 p. + 1 fold. map
Abstract: Sheet P26AC & part P25 includes D'Urville Island, Stephens Island, and the northwestern Marlborough Sounds. The area is dominated by rocks of Permian-Mesozoic age comprising the Drumduan, Brook Street, Murihiku, Dun Mountain-Maitai, and Caples terranes. Deformation occurred when the various terranes were sutured to each other in the Mesozoic. Reactivation of contacts between many terranes in the mid or late Cenozoic mainly resulted in replacement of sutures by reverse dextral faults, the most important being the Waimea and Flaxmore faults of the Waimea-Flaxmore Fault System. Movement on the fault system resulted in formation of the east Nelson ranges, and depression of northern Marlborough and the area west of the Waimea Fault. Subsequent marine invasion during Pleistocene interglacials formed the Marlborough Sounds in the north and Tasman Bay in the west. Quaternary sediments occur in isolated pockets. Blocks of sedimentary rock in melanges were a source of implements for pre-European maori Mineral prospected since European settlement include serpentinite, copper, chromite, sulphides, asbestos, limestone, and talc. A petroleum seep has been reported. Landslides are common particularly in the weathered, slightly foliated (t.z. HA) Pelorus Group and, along with earthflows, in the serpentinitic melanges. Most are stable under present day conditions, but some are active, particularly where subject to coastal erosion. Although faulting is widespread, only the Waimea and Flaxmore faults are potentially active. The area also has a high earthquake risk from ground shaking originating from faults in the surrounding area. Tsunami risk is high in coastal area. (auth)
