Lithostratigraphy of the basal Waitemata Group, Kawau Subgroup (new), Auckland, New Zealand

Abstract

Abstract The basal strata (Otaian, early Miocene) of the Waitemata Group in the Auckland region of northern New Zealand consist of a 10–45 m thick, heterogeneous assemblage of shallow marine sediments, distinct from the overlying, deep-water sandstone and siltstone that form the bulk of the group. In the north they partly fill depressions in the underlying, highly irregular greywacke surface, and in the south form a veneer over the more planar, eroded Te Kuiti Group surface. Kawau Subgroup is proposed for all the basal Waitemata Group rocks that crop out from Cape Rodney in the north to Raglan in the south and Cape Colville in the east. Three formations are recognised: (1) Papakura Limestone (much enlarged) = lenses of pebbly, gritty, shelly or sandy bioclastic limestone and local limestone breccia with associated thin lenses of shelly sandstone and conglomerate. Three members are described—Motuketekete Limestone, Purser Limestone, and Te Akau Members (all new); (2) Tipakuri Sandstone Formation (new) = le...