ABSTRACT

The modern active volcanic setting of the North Island, New Zealand, includes arc volcanism at the young Taupo Volcanic Zone (< 350 ka) and intraplate basaltic volcanism at the Auckland Volcanic Field (< 200 ka). These volcanic settings are markedly different in character and origin, however, the geographic position of the arc volcanoes and intraplate fields have migrated almost in unison across the western North Island over the last three million years. This article reviews the characteristics and volcanic histories of central North Island volcanic centres and fields that were active from 3.0 to 0.9 Ma, including: the silicic Tauranga and Mangakino volcanic centres; the andesitic Pureora, Titiraupenga and Maungatautari stratovolcanoes; the basaltic Alexandra Volcanic Group, which comprises a chain of stratovolcanoes and an interspersed (Okete) volcanic field; and the basaltic Ngatutura and South Auckland volcanic fields. New U-Pb zircon and (U-Th)/He zircon ages for rhyolites and one ignimbrite in the Tauranga Volcanic Centre adds to and confirms the existing dates, as well as confirming the overall age range for this centre. Synchronous volcanism at the Tauranga Volcanic Centre and the Alexandra Volcanic Group is a historic marker for the origin of the modern arc and intraplate settings.

摘要

新西兰北岛现代活跃的火山环境包括年轻的陶波火山带 (< 350 ka) 的弧形火山作用和奥克兰火山场 (< 200 ka) 的板内玄武岩火山作用。这些火山环境在特征和起源上明显不同，然而，弧形火山和板内场的地理位置在过去三百万年中几乎同时迁移到北岛西部。本文回顾了活跃于 3.0 至 0.9 Ma 的北岛中部火山中心和火山场的特征和火山历史，包括：硅质陶朗加和曼加基诺火山中心；安山岩 Pureora、Titiraupenga 和 Maungatautari 层状火山；玄武岩亚历山德拉火山群，它包括一连串层状火山和一个散布的 (Okete) 火山场；以及玄武岩 Ngatutura 和南奥克兰火山区。新的 U-Pb 锆石和 (U-Th)/He 锆石流纹岩和陶朗加火山中心的一个冰凝灰岩年龄增加并确认了现有日期，并确认了该中心的整体年龄范围。陶朗加火山中心和亚历山德拉火山群的同步火山活动是现代弧形和板内环境起源的历史标志。