Age relationships of theGlobigerinoides Trilobuszone and the andesite at Muriwai quarry, New Zealand

Abstract
Basic andesite at Muriwai, New Zealand, occurs within upper bathyal deposits of the Lower Miocene. Its biostratigraphic position is just below the point of origin of Globigerinoides bisphericus (sicanus) from Globigerinoides trilobus. This is within the Awamoan Stage of New Zealand, it is correlative with the upper Saucesian Stage of California, the Burdigalian of Europe, zone N-7 of Banner and Blow, and it is within the Globigerinatella insueta zone as redefined by Bolli in 1966. The potassiumargon age of 16.8 million years B.P. provides an important datum within the upper part of the Lower Miocene.