Recognition and correlation of the Kapitean Stage (Upper Miocene, New Zealand)

Abstract

The salient features of New Zealand Upper Miocene and Lower Pliocene microfaunas are outlined, and criteria for recognising the Kapitean Stage are summarised. Paleoecological evidence suggests that the Kapitean Age was a time when seas were relatively shallow, that the shallowing took place in the latest part of the Tongaporutuan Age, and that deepening took place in the earliest part of the Opoitian Age. The changes in sea level caused many changes in the fauna, and the Kapitean Stage is soundly based only on relatively few permanent changes of both macrofauna and microfauna. The Kapitean Stage is represented by shallow-water facies at many places, but it contains some moderately deep-water facies at other places. The two facies contain very few diagnostic fossils which are common to both, but usually can be correlated by a bioseries of planktonic Foraminifera—the Globorotalia crassaformis bioseries. In nearly all sections the Kapitean Stage is thin compared with the overlying Opoitian and the underlying Upper Tongaporutuan, and this is attributed to a decreased rate of deposition caused by shallowing and increased by-passing of sediment. Kapitean microfaunas show a slight but distinct change from north to south, and this is attributed to latitudinal temperature difference. The previously proposed correlation of the Kapitean Stage with the Pontian Stage of Europe is probably correct. The predominantly shallow seas during the Kapitean Age in New Zealand appear to have coincided with a regression in Europe and in other parts of the world, and are likely to have a eustatic rather than a tectonic cause.