Correlation of basement rocks from Waka Nui‐1 and Awhitu‐1, and the Jurassic regional geology of Zealandia

Abstract

Core and cuttings of sandstone and mudstone from Waka Nui‐1, an offshore oil exploration well west of Northland, and from Awhitu‐1, a water bore in western Auckland, add to the growing number of samples retrieved from otherwise inaccessible basement of the Zealandia continent. On the basis of pollen and spores, the sedim entary rocks at the bottom of Waka Nui‐1 are dated as Early‐Middle Jurassic, and rocks from Awhitu‐1 are Late Jurassic. On the basis of age, sandstone petrology, and geographic position, a correlation of rocks in both wells with Murihiku Terrane is probable. In New Zealand, Jurassic sedimentary rocks have usually been interpreted in a tectonostratigraphic terrane context. An alternative way to look at the New Zealand Late Jurassic to Early Cretaceous sedimentary rocks is as potentially interconnected forearc, intra‐arc, back‐arc, and intracontinental basins that evolved adjacent to an active margin.

Keywords:

• Jurassic
• Zealandia
• Murihiku Terrane
• sandstone
• palynology
• petrology