Late Eocene‐Oligocene Te Kuiti Group at Mount Roskill, Auckland, New Zealand

Abstract

A 592 m deep water bore drilled at Mount Roskill in central Auckland, New Zealand, intersected products of the Auckland Volcanic Field (0–12 m), pumiceous sediments of the Tauranga Group (12–23 m), interbedded sandstone and mudstone of the Waitemata Group (23–475 m), and Te Kuiti Group sediments (475–592 m). This first record of Te Kuiti Group in the central Auckland area comprises erosionally truncated Glen Massey Formation beneath the Waitemata Group, a complete section through Mangakotuku Formation, and an incomplete Waikato Coal Measures section. Drilling stopped in Waikato Coal Measures, probably less than 30 m short of Paleozoic or Mesozoic basement. Vitrinite reflectance measurements indicate a lignite rank for coal fragments collected from the coal measures, and suggest a maximum burial depth of c. 800 m. Six Te Kuiti Group samples examined for palynomorphs and foraminifers gave ages ranging from Runangan to early Whaingaroan and show a transition from a predominantly terrestrial late Eocene environment to a shallow marine setting in the early Oligocene. This result helps substantiate previous inferences about the continuity of Te Kuiti Group deposition between Northland and Waikato, and supports the suggestion that the southern limit to the Northland Allochthon lies north of Auckland.