Distribution and biostratigraphy of latest Eocene to latest Oligocene Radiolaria from the Mahurangi Limestone, Northland, New Zealand

Abstract

Radiolaria from the Mahurangi Limestone are generally common to abundant, well preserved, and the faunas reasonably diverse. However, all published information concerning these radiolarian faunas concentrates on the description of new species. This leaves useful data on location, density, abundance, preservation, biostratigraphy, and distribution unpublished. Data on 50 radiolarian-bearing samples from 30 localities spanning the geographical range of the Mahurangi Limestone are presented. Forty-three of these samples, from 25 localities, contain radiolarian age index taxa. More than 179 radiolarian taxa are identified, from over 89 genera, and diversity ranges up to 136 taxa per sample. Fifteen radiolarian index species can be identified within the Mahurangi Limestone, allowing many localities to be dated on radiolarian evidence alone. For age control, nannofossil age data from samples containing radiolarian age indicators are also presented. Radiolaria give an age range for the Mahurangi Limestone of latest Eocene to latest Oligocene. New or updated information includes a locality map, data on radiolarian densities, abundances and preservation for each sample, biostratigraphic information, a full list of radiolarian taxa identified from the Mahurangi Limestone, and tables of radiolarian distribution within the studied samples. A diagram correlating international and New Zealand stages with new information on South Pacific and tropical radiolarian zones for the latest Eocene to earliest Miocene is also provided, together with stratigraphic ranges for radiolarian index species used for dating the Mahurangi Limestone. © 1999 Taylor & Francis Group, LLC.