ABSTRACT Maungatautari is an extinct, andesitic-dacitic composite cone situated 35 km southwest of Hamilton, New Zealand. This study examines the volcanic history and petrologic evolution of Maungatautari using field mapping, petrography of pyroclastic successions and lavas, and whole rock and isotope analyses of selected lavas. Lavas consist of non-vesicular labradorite, pyroxene and hornblende andesites and dacites. A small cone of olivine basalt is located at Kairangi, 7 km to the northwest of the Maungatautari trig. Whole rock geochemical and strontium and neodymium analyses demonstrate that these lavas were derived from at least three distinct mantle-melt sources. Mass-wasting processes continue to shape the mountain post volcanic activity and include catastrophic failure of the north-eastern flank which produced a 0.28 km3 rock avalanche deposit. This study considers Maungatautari to reflect andesitic-dacitic arc volcanism occurring within the upper North Island c. 2 Ma.

中文翻译：

---

新西兰怀卡托中部早更新世安山-英安岩 Maungatautari 复合锥的火山形成过程和岩石成因

摘要 Maungatautari 是一个已灭绝的安山岩-英安岩复合锥，位于新西兰汉密尔顿西南 35 公里处。本研究使用野外测绘、火山碎屑序列和熔岩的岩石学以及选定熔岩的全岩和同位素分析来检查 Maungatautari 的火山历史和岩石演化。熔岩由非泡状拉长石、辉石和角闪石安山岩和英安岩组成。一小块橄榄石玄武岩锥体位于 Maungatautari 三角洲西北 7 公里处的 Kairangi。全岩地球化学和锶和钕分析表明，这些熔岩至少来自三个不同的地幔熔体来源。质量消耗过程继续塑造火山后的火山活动，包括东北侧的灾难性故障产生了 0。28 平方公里的岩石雪崩矿床。本研究认为 Maungatautari 反映了北岛上部 c 内发生的安山岩-英安岩弧火山作用。2 马。