ABSTRACT

The cataclysmic basaltic eruption of Mt. Tarawera in 1886 represents a significant cultural and scientific event for New Zealand. This review utilises published and new observations, to reinterpret eruptive parameters encompassing the entirety of the eruption. The ∼17 km eruptive fissure, active for 4+ hours, extends across Mt. Tarawera to the hydrothermally active Waimangu region. Correlating published observations of bed thickness, componentry and microtextures from Mt. Tarawera to new bed descriptions and granulometry for the Rotomahana-Waimangu rift segment allows for a re-assessment of eruption variations along the length of the fissure. Variably thick pyroclastic fall sequences at Mt. Tarawera contrast with the pyroclastic surges and an eruption plume that together deposited the ‘Rotomahana Mud’ erupted along the Rotomahana-Waimangu segment. Providing insight into pre-eruptive conditions, new mineral chemistry from Mt. Tarawera provides the first constraints on crystallisation pressures (<2 kbar), temperatures (<1100°C), and magmatic water content (<2.8 wt%). Recalculated volumes indicate a bulk eruptive volume of 1.1–1.3 km³, and a juvenile basalt volume of up to 0.67 km³, which then lead to calculated discharge rates of 3.7 × 10⁷–7.8 × 10⁷ kg s⁻¹ for the northern Mt. Tarawera segment of the fissure and 1.4–5.7 × 10⁶ kg s⁻¹ for the Rotomahana segment.

摘要

山的灾难性玄武岩喷发。1886 年的塔拉威拉（Tarawera）代表了新西兰重要的文化和科学事件。该评论利用已发表的和新的观察结果来重新解释涵盖整个喷发的喷发参数。约 17 公里的喷发裂缝，活动时间超过 4 小时，延伸到山上。Tarawera 到热液活跃的 Waimangu 地区。将已发表的对 Mt. 的床厚度、成分和微观纹理的观察结果进行关联。Tarawera 对 Rotomahana-Waimangu 裂谷段的新床描述和粒度测量允许重新评估沿裂隙长度的喷发变化。Mt. 不同厚度的火山碎屑坠落序列。塔拉威拉与火山碎屑浪涌和喷发羽流形成对比，这些喷发羽流共同沉积了沿着 Rotomahana-Waimangu 段喷发的“Rotomahana Mud”。提供对喷发前条件的深入了解，来自 Mt. 的新矿物化学。Tarawera 提供了对结晶压力 (<2 kbar)、温度 (<1100°C) 和岩浆含水量 (<2.8 wt%) 的第一个限制。重新计算的体积表明大量喷发体积为 1.1-1.3 公里³，以及高达 0.67 km ³的幼年玄武岩体积，这导致北部山的计算排放率为 3.7 × 10 ⁷ –7.8 × 10 ⁷ kg s ^-1。裂隙的 Tarawera 段和 Rotomahana 段的 1.4–5.7 × 10 ⁶ kg s ^-1。