Cretaceous-tertiary boundary at woodside creek, north-eastern Marlborough

Abstract

The Cretaceous-Tertiary boundary lies about 60 m above the base of the Mead Hill Formation in a section exposed in the narrow gorge of Woodside Creek in north-eastern Marlborough, New Zealand. The contact is marked by a disconformity separating thinly bedded siliceous limestone of the upper Mead Hill Formation from more thickly bedded flinty limestone below. The upper limestone, which contains Globigerina (Globoconusa) daubjergensis Bronnimann and G. (Subbotina) triloculinoides Plummer is of mid-Teurian (Danian) age. The underlying limestone is of late Haumurian (Maastrichtian) age, as indicated by the occurrences of Globo-truncana (Abathomphalus) mayaroensis Bolli, G. (A.) intermedia Bolli, G. (Rugotruncana) circumnodifer (Finlay), and Bolivinoides draco dorreeni Finlay. Lower Teurian rocks apparently are missing, along with an indeterminable thickness of latest Cretaceous strata. The Haumurian limestones probably were deposited in relatively deep water; depths of about 200–600 m are indicated. Foraminiferal evidence suggests warm temperate surface temperatures. Teurian strata seem to have been deposited under shallower conditions, in water depths of perhaps 100–200 m. Cooler, more temperate surface conditions than during the preceding Cretaceous interval may have prevailed.