ABSTRACT

Ruapehu (150 km³ cone, 150 km³ ring-plain) and Tongariro (90 km³ cone, 60 km³ ring-plain) are iconic stratovolcanoes, formed since ∼230 and ∼350 ka, respectively, in the southern Taupo Volcanic Zone and Taupo Rift. These volcanoes rest on Mesozoic metasedimentary basement with local intervening Miocene sediments. Both volcanoes have complex growth histories, closely linked to the presence or absence of glacial ice that controlled the distribution and preservation of lavas. Ruapehu cone-building vents are focused into a short NNE-separated pair, whereas Tongariro vents are more widely distributed along that trend, the differences reflecting local rifting rates and faulting intensities. Both volcanoes have erupted basaltic andesite to dacite (53–66 wt.% silica), but mostly plagioclase-two pyroxene andesites from storage zones at 5–10 km depth. Erupted compositions contain evidence for magma mixing and interaction with basement rocks. Each volcano has an independent magmatic system and a growth history related to long-term (>10⁴ years) cycles of mantle-derived magma supply, unrelated to glacial/interglacial cycles. Historic eruptions at both volcanoes are compositionally diverse, reflecting small, dispersed magma sources. Both volcanoes often show signs of volcanic unrest and have erupted with a wide range of styles and associated hazards, most recently in 2007 (Ruapehu) and 2012 (Tongariro).

摘要

Ruapehu（150 公里³锥体，150 公里³环形平原）和汤加里罗（90 公里³锥体，60 公里³环形平原）是标志性的成层火山，分别形成于约 230 和约 350 ka，分别在陶波火山带南部和陶波裂谷中形成。这些火山位于中生代变质沉积基底上，当地夹杂着中新世沉积物。两座火山都有复杂的生长历史，与控制熔岩分布和保存的冰川冰的存在或不存在密切相关。Ruapehu 锥形构造喷口集中成一个短的 NNE 分离对，而汤加里罗喷口沿该趋势分布更广泛，差异反映了局部裂谷率和断层强度。两座火山都将玄武质安山岩喷发为英安岩（53–66 wt.% 二氧化硅），但主要是来自 5–10 公里深度储存区的斜长石-二辉石安山岩。喷发的成分包含岩浆混合和与基底岩石相互作用的证据。每座火山都有独立的岩浆系统和与长期（>10⁴年）地幔来源的岩浆供应周期，与冰期/间冰期周期无关。两座火山的历史喷发在成分上各不相同，反映了小的、分散的岩浆源。这两座火山经常表现出火山动荡的迹象，并以各种形式和相关的危险喷发，最近一次是在 2007 年（鲁阿佩胡）和 2012 年（汤加里罗）。