Stratigraphy of the Waipawa Black Shale (Paleocene), eastern North Island, New Zealand

The Waipawa Black Shale (Formation) is a dark brown to brownish black micaceous siltstone of Teurian (Paleocene) age, widely distributed in eastern North Island. Thickness ranges from a few metres to more than 50 m. It conformably overlies siliceous shale of the Whangai Formation (Late Cretaceous-early Paleocene: Haumurian-Teurian), and is generally overlain conformably or disconformably by smectite-rich calcareous mudstone of the Wanstead Formation (late Paleocene-Eocene). The shale, because of its distinctive colour and stratigraphic position, represents an important marker horizon in the Late Cretaceous-Paleogene sequence of eastern North Island. Eleven key stratigraphic sections, in various parts of the region, are described. Correlation of these sections, together with other evidence, indicates the Waipawa Black Shale is a lateral equivalent (in part) of the uppermost Whangai Formation, and that the base may be markedly diachronous in some areas.