Dinoflagellate biostratigraphy of Piripauan-Haumurian (Upper Cretaceous) sections from northeast South Island, New Zealand

Abstract

Palynological analysis of two sections at Haumuri Bluff and Conway River (southern Marlborough, New Zealand), and three sections in the Waipara area (northern Canterbury, New Zealand), of Piripauan-Haumurian age (Late Cretaceous), shows that: (1) in southern Marlborough the Okarahia Sandstone was deposited in a marginal marine nearshore environment, and the overlying Tarapuhi Grit, Conway Siltstone and Claverley Sandstone were deposited in open marine environments with considerable influx of terrestrial organic material; (2) in northern Canterbury the Broken River Formation is mainly non-marine, with minor marine incursions indicated by the low diversity dinoflagellate assemblages; the overlying Conway Siltstone was deposited in a marginal marine, nearshore environment. A qualitative analysis of the dinoflagellate assemblages shows that in the type section for the Piripauan and Haumurian stages (Haumuri Bluff, southern Marlborough), the Piripauan Okarahia Sandstone is of late Coniacian to early Santonian age, and the Haumurian Tarapuhi Grit is of early to mid Campanian age. Hence, the Piripauan Stage stratotype and the base of the Haumurian Stage stratotype are separated by an unconformity encompassing the mid-upper Santonian. In southern Marlborough, the Haumurian Conway Siltstone and the lower part of the Claverley Sandstone together span the Campanian. In northern Canterbury, the Haumurian Broken River Formation is of mid to late Campanian age; the base of the overlying Conway Siltstone is here of late Campanian to early Maastrichtian age; the top of the Conway Siltstone is of latest early to late Maastrichtian age. The following succession of dinoflagellate zones is recognised in the sections: Conosphaeridium abbreviatum Interval Zone (late Coniacian-early Santonian), Odontochitina porifera Interval Zone (early Santonian), Satyrodinium haumuriense Interval Zone (early to mid Campanian), Isabelidinium korojonense Interval Zone (new definition) (mid-late Campanian), I. pellucidum Interval Zone (mid-late Campanian), Alterbidinium acutulum Interval Zone (late Campanian-early Maastrichtian) and Manumiella druggii Zone (latest early to late Maastrichtian). The S. haumuriense Interval Zone is subdivided into three subzones: Trithyrodinium suspectum Interval Subzone,Vozzhennikovia spinulosa Interval Subzone and Canninginopsis bretonica Interval Subzone. The A. acutulum Interval Zone is subdivided into two subzones: Cerodinium diebelii Interval Subzone and Palaeocystodinium granulatum Interval Subzone. Four new dinoflagellate species are described: Alterbidinium longicornutum sp. nov.,Batiacasphaera grandis sp. nov., Diconodinium vitricornu sp. nov., and Isabelidinium brunae sp. nov.