Geology of the Pukekohe area

This new 1:50,000 geological map covers 830 km2 between the southern shoreline of Manukau Harbour and the lower Waikato River. The area, which includes Pukekohe, Waiuku, Pōkeno, and Papakura townships. Basement rocks (Austral Superprovince) beneath the map area consist of three fault-bounded, meta-sedimentary and meta-igneous terranes of Permian to Early Cretaceous age, although it is only Triassic–Jurassic ‘greywacke’ rocks of Waipapa Composite Terrane that crop out. An overlying succession of cover strata (Zealandia Megasequence), in places >1 km thick, consists of Late Eocene–Early Miocene non- to deep-marine sedimentary rocks (Te Kuiti, Waitematā, and Waitākere groups) unconformably overlain by Pliocene to Holocene terrestrial and shallow-marine sedimentary strata (Tauranga Group). Intra-plate effusive and explosive basaltic volcanism of Early to Middle Pleistocene age (South Auckland Volcanic Field) underpins the distinctive landscape within the southern parts of the map area. Distal airfall and pyroclastic flow deposits from North Island’s Central Volcanic Region have further modified the region’s landscape.