ABSTRACT

Mt. Taranaki is an andesitic stratovolcano in the western North Island of New Zealand. Its magmas show slab-dehydration signatures and over the last 200 kyr they show gradually increasing incompatible element concentrations. Source basaltic melts from the upper mantle lithosphere pond at the base of the crust (∼25 km), interacting with other stalled melts rich in amphibole. Evolved hydrous magmas rise and pause in the mid crust (14–6 km), before taking separate pathways to eruption. Over 228 tephras erupted over the last 30 kyr display a 1000–1500 yr-periodic cycle with a five-fold variation in eruption frequency. Magmatic supply and/or tectonic regime could control this rate-variability. The volcano has collapsed and re-grown 16 times, producing large (2 to >7.5 km³) debris avalanches. Magma intrusion along N-S striking faults below the edifice are the most likely trigger for its failure. The largest Mt. Taranaki Plinian eruption columns reach ∼27 km high, dispersing 0.1 to 0.6 km³ falls throughout the North Island. Smaller explosive eruptions, or dome-growth and collapse episodes were more frequent. Block-and-ash flows reached up to 13 km from the vent, while the largest pumice pyroclastic density currents travelled >23 km. Mt. Taranaki last erupted in AD1790 and the present annual probability of eruption is 1–1.3%.

摘要

公吨。塔拉纳基是新西兰北岛西部的安山岩层状火山。它的岩浆显示出板块脱水特征，在过去的 200 kyr 中，它们显示出逐渐增加的不相容元素浓度。源玄武岩熔体来自地壳底部（约 25 公里）的上地幔岩石圈池，与其他富含角闪石的停滞熔体相互作用。演化出的含水岩浆在中地壳（14-6 公里）上升和停顿，然后通过不同的途径喷发。在过去的 30 kyr 中，超过 228 个火山喷发显示出一个 1000-1500 年的周期循环，喷发频率有五倍的变化。岩浆供应和/或构造体制可以控制这种速率变化。火山已经坍塌并重新生长了 16 次，产生了巨大的（2 到 >7.5 km ³) 碎片雪崩。沿着建筑物下方的 NS 显着断层的岩浆侵入是其失败的最可能触发因素。最大的山 塔拉纳基普林尼亚火山喷发柱高达 27 公里，在整个北岛散布着 0.1 至 0.6 公里^{3 的}瀑布。较小的爆发性喷发，或圆顶生长和坍塌事件更为频繁。块状和灰烬流从喷口处达到 13 公里，而最大的浮石火山碎屑流密度超过 23 公里。公吨。塔拉纳基最后一次喷发是在公元 1790 年，目前每年喷发的概率为 1-1.3%。