Details - Taxonomy and paleoecology of Early Miocene benthic foraminifera of northern New Zealand and the north Tasman Sea

Taxonomy and paleoecology of Early Miocene benthic foraminifera of northern New Zealand and the north Tasman Sea

Title

Taxonomy and paleoecology of Early Miocene benthic foraminifera of northern New Zealand and the north Tasman Sea

Related Titles

Related/Analytical: Taxonomy and paleoecology of early Miocene benthic foraminifera ...

Series: Smithsonian contributions to paleobiology, no. 36

By

Hayward, Bruce W. (Bruce William)

Buzas, Martin A.

Type

Book

Material

Published material

Publication info

Washington, Smithsonian Institution Press, Smithsonian Institution, 1979

Notes

Includes index.

Data from 51 samples of early Miocene benthic foraminifera (200-300 individuals per sample) from west Northland, New Zealand (Waitakere and Waitemata Groups), together with those from four samples from the north Tasman sea (Deep Sea Drilling Project 206), are analysed by multidimensional scaling and cluster analysis. The samples are grouped in terms of species abundances into six thanatotopes, which are interpreted as follows: A, dominated by robust Amphistegina madagascariensis, 10%-37% planktonics, inner neritic; B, Cibicides-Cibicidoides dominant, 10%-55% planktonics, outer neritic; C, Gyroidina, Euuvigerina, Astrononion, Lenticulina most abundant, 32%-87% planktonics, upper bathyal; D, Cassidulina-Bolivina-Cibicides dominant, 16%-99.5% planktonics, upper and midbathyal; E, Globocassidulina-Epistominella dominant, 99.5% planktonics, lower bathyal; F, Quinqueloculina dominant, 11%-32% planktonics, inner and midneritic.Using these thanatotope interpretations in conjunction with their stratigraphic and geographic distributons, a model of the early Miocene paleogeography of west Northland is deduced, refining traditional models for the area. A central mid-bathyal basin (Waitemata Basin), bounded in the southwest by a pile of volcanic sediments (Waitakere volcanic pile), built up to an island surrounded by neritic and upper bathyal slopes. In the northwest (Kaipara area) volcanics erupted through a neritic shelf. This shelf became shallower and partly terrestrial during latter parts of the early Miocene. Upper bathyal slopes existed around the southern edge of the northwestern shelf. Submarine canyons cut through these slopes channeling shelf sediment into the bathyal basin. Several ungrouped, greatly mixed samples (interbedded with basin sediments) contain individuals from neritic and bathyal thanatotopes and are interpreted as having been mixed during transportation down through the canyons into the basin in the form of subaqueous sediment gravity flows.No change in depth from the present lower bathyal is inferred to have occurred in the vicinity of DSDP 206 (north Tasman Sea) since the early Miocene.All 378 identified species are listed together with their synonomies; many are described and 194 species are figured. Besides a number of first records for New Zealand, three new species—Elphidium gibsoni, Elphidium kanoum, and Eoeponidella scotti—are described.