Preeruptive Stratification of the Oruanui Rhyolitic Magma, Taupo Volcanic Center, New Zealand

AndersonEAR-0106327拟议的研究集中在Orunaui流纹质火山灰流凝灰岩上，这是一种地质上年轻的、与Bishop凝灰岩形成鲜明对比的凝灰岩。我们计划测试喷发前的Oruanui岩浆是否稳定分层。如果不系统地喷发的Oruanui浮石成分仍然来自密度层状岩浆体，那么将强化这样的观点，即许多硅质岩浆大体可能通过岩浆形成、侵位、结晶和气体出溶的自然过程实现稳定的密度层化。我们将通过研究石英和其他斑晶中玻璃的包裹体和折返物来研究岩浆的喷发前状态，因为这些似乎保存了喷发前条件的记录，几乎没有被喷发减压、气体出溶和结晶所改变。我们的研究将有助于理解硅质行星壳的形成以及硅质岩浆活动体的行为，包括它们喷发的倾向以及与地热系统的相互作用，地热系统是矿床和能量产生的场所。

AndersonEAR-0106327The proposed research focusses on the Orunaui rhyolitic ash-flow tuff, a geologically young and contrasting counterpart to the Bishop Tuff. We plan to test whether the preeruptive Oruanui magma was stably stratified. If the unsystematically erupted Oruanui pumice compositions nevertheless derive from a density stratified magma body, then the case will be strengthened that many big bodies of silicic magma probably achieve a stable density stratification by natural processes of magma formation, emplacement, crystallization and exsolution of gas. We will study the preeruptive state of the magma by studying inclusions and reentrants of glass in quartz and other phenocrysts, because these plausibly preserve a record of the preeruptive conditions, little modified by eruptive decompression, gas exsolution and crystallization. Our study will help understand the formation of silicic planetary crusts as well as the behavior of active bodies of silicic magma including their propensity for eruption and interactions with geothermal systems, which are sites of ore deposition and energy production.