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Viscous flow of magmas from Unzen volcano, Japan - implications for magma mixing and ascent

日本云仙火山的岩浆粘性流——对岩浆混合和上升的影响

基本信息

批准号：
5363482
负责人：
Professor Dr. Harald Behrens
金额：
--
依托单位：
Institut für Mineralogie
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2002
资助国家：
德国
起止时间：
2001-12-31 至 2007-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/5363482?language=en
关键词：
Viscous flow magmas Unzen volcano

项目摘要

In the proposed project the viscosity of magmas of the Unzen volcano in Japan (compositions: rhyodacite to andesite) will be determined at conditions relevant to the local geological situation. Effects of pressure, water content, redox state of iron and degree of crystallization on rheological properties of the magma are of special importance in our studies. At present the influence of these parameters on viscosity of rhyodacitic to andesitic melts can not be modeled due to a lack of reliable experimental data. In the high-viscosity range nearby the glass transition, viscosities will be measured under pressure using a parallel-plate viscometer developed in our institute. Previous measurements were performed only at ambient pressure in this viscosity range. In the low-viscosity range (stable melt), the fallingsphere method will be applied. Combining both methods, the temperature dependence of viscosity can be defined in a large T range. Based on our viscosity measurements and on data from literature we want to develop a viscosity model applicable to melts with rhyolitic to andesitic composition. Using the viscosity data and results on phase equilibria and volatile solubility (project Ho1337/3+7), an attempt will be made to reconstruct the evolution of Unzen magmas from pre-eruptive conditions to the beginning of the eruption.

在拟议的项目中，将在与当地地质情况有关的条件下确定日本云仙火山岩浆（成分：流纹英安岩至安山岩）的粘度。压力、含水量、铁的氧化还原状态和结晶度对岩浆流变学性质的影响在我们的研究中具有特别重要的意义。目前，由于缺乏可靠的实验数据，这些参数对流纹英安质-安山质熔体粘度的影响还不能模拟。在玻璃化转变附近的高粘度范围内，粘度将使用本研究所开发的平行板粘度计在压力下测量。先前的测量仅在该粘度范围内的环境压力下进行。在低粘度范围（稳定熔体），将采用落球法。结合这两种方法，粘度的温度依赖性可以定义在一个大的T范围。基于我们的粘度测量和文献数据，我们要开发一个粘度模型适用于流纹岩安山岩组成的熔体。使用粘度数据和结果的相平衡和挥发性溶解度（项目Ho 1337/3+7），将试图重建云仙岩浆从喷发前的条件开始喷发的演变。