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Magma residence and eruption at the Taupo Volcanic Center (Taupo Volcanic Zone, New Zealand): insights from rhyolite-MELTS geobarometry, diffusion chronometry, and crystal textures
Contributions to Mineralogy and Petrology ( IF 3.5 ) Pub Date : 2020-04-21 , DOI: 10.1007/s00410-020-01684-2
Ayla S. Pamukçu , Kylie A. Wright , Guilherme A. R. Gualda , Darren Gravley

The Taupo Volcanic Center [TVC; Taupo Volcanic Zone (TVZ), New Zealand] is home to the two most recent silicic caldera-forming eruptions in the TVZ—the giant (530 km 3 DRE) Oruanui supereruption and the large (35 km 3 DRE) Taupo eruption. This offers a unique opportunity to investigate similarities and differences between large and supersized volumes of rhyolitic magma at the TVC and more generally. We combine information from crystal textures (crystal size distributions), crystal compositions (Ti-in-quartz diffusion chronometry), and glass compositions (rhyolite-MELTS geobarometry) to investigate the crustal storage conditions, longevity, and eruption of these magmas. Results show differences between the storage depths of the Oruanui and Taupo magmas consistent with the differences in their glass silica contents but strikingly similar, short crustal residence times for the final crystal-poor, eruptible magma bodies (decades to centuries). Differences in groundmass textures between the two systems also likely reflect differences in ascent durations, decompression paths, and/or amounts of undercooling experienced by these systems due to the differences in their storage depths. Finally, comparing the evolution of storage depths and magma compositions at the TVC with those in a preceding central TVZ ignimbrite ‘flare-up’ supports the idea that the modern TVC may be flaring up and highlights the evolution of magma storage depths with increasing system maturity in this volcanic region.

中文翻译:

陶波火山中心(新西兰陶波火山区)的岩浆滞留和喷发:来自流纹岩-熔融地理气压测量、扩散计时和晶体结构的见解

陶波火山中心 [TVC; Taupo Volcanic Zone (TVZ), New Zealand] 是 TVZ 中最近两次形成硅质火山口的火山喷发的所在地——巨型(530 公里 3 DRE)奥鲁努伊超级喷发和大型(35 公里 3 DRE)陶波火山喷发。这提供了一个独特的机会来研究 TVC 以及更普遍的大型和超大型流纹质岩浆之间的异同。我们结合来自晶体结构(晶体尺寸分布)、晶体成分(石英中的钛扩散计时)和玻璃成分(流纹岩-熔融地理气压测量)的信息来研究这些岩浆的地壳储存条件、寿命和喷发。结果显示奥鲁努伊岩浆和陶波岩浆储存深度之间的差异与其玻璃二氧化硅含量的差异一致,但惊人地相似,最后结晶贫乏、可喷发的岩浆体的地壳停留时间很短(几十到几百年)。两个系统之间地块质地的差异也可能反映了这些系统由于储存深度不同而经历的上升持续时间、减压路径和/或过冷量的差异。最后,将 TVC 的储存深度和岩浆成分的演变与之前中央 TVZ 燃烧“爆发”中的演变进行比较,支持现代 TVC 可能正在爆发的观点,并强调了随着系统成熟度的提高,岩浆储存深度的演变在这个火山区。两个系统之间地块质地的差异也可能反映了这些系统由于储存深度不同而经历的上升持续时间、减压路径和/或过冷量的差异。最后,将 TVC 的储存深度和岩浆成分的演变与之前中央 TVZ 燃烧“爆发”中的演变进行比较,支持现代 TVC 可能正在爆发的观点,并强调了随着系统成熟度的提高,岩浆储存深度的演变在这个火山区。两个系统之间地块质地的差异也可能反映了这些系统由于储存深度不同而经历的上升持续时间、减压路径和/或过冷量的差异。最后,将 TVC 的储存深度和岩浆成分的演变与之前中央 TVZ 燃烧“爆发”中的演变进行比较,支持现代 TVC 可能正在爆发的观点,并强调了随着系统成熟度的提高,岩浆储存深度的演变在这个火山区。
更新日期:2020-04-21
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