Pre-eruptive conditions prior to and after magma mixing at Unzen volcano: constraints from high pressure experimental investigations

云仙火山岩浆混合前后的喷发前条件：高压实验研究的限制

• 批准号: 5423440
• 负责人: Professor Dr. Francois Holtz, Ph.D.
• 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: 2004
• 资助国家: 德国
• 起止时间: 2003-12-31 至 2007-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5423440?language=en
• 关键词: Pre; eruptive; conditions; prior; after

The 1991-1995 eruption of Unzen is initiated by a mixing event (as observed in many eruptive systems) between a low-temperature phenocryst-rich dacitic magma and a high temperature andesitic magma Thus, understanding pre-eruptive conditions requires to determine pre-mixing conditions (in the two end-member magmas) and post-mixing conditions, and to model the processes occurring during mixing and ascent. In Unzen volcano, only post-mixing conditions in the magma chamber are well-characterized. The proposed project should contribute to provide new constraints on the pre-mixing magmas, especially the high temperature end-member, (including volatile contents, melt and phenocryst compositions) and on processes occurring during mixing and magma ascent. These constraints will be obtained from high pressure - high temperature experimental investigations on phase relations and volatile solubilities in silicate melts. The comparison of natural samples from the volcanic dome (including andesitic enclaves) and from the ICDP-drilling with experimental results will be used to understand the role of mixing (and possible subsequent degassing) on magma forcing and the role of kinetic processes during magma ascent (degassing, crystallization in a dynamic system).

1991-1995年的云仙火山喷发是由低温富斑晶英质岩浆与高温安山岩岩浆的混合事件（在许多喷发系统中都观察到）引发的。因此，了解喷发前条件需要确定混合前条件（在两个端元岩浆中）和混合后条件，并对混合和上升过程进行建模。在云仙火山中，只有岩浆房的后混合条件得到了很好的描述。建议的项目将有助于对预混合岩浆，特别是高温端元（包括挥发性成分、熔体和斑晶成分）以及混合和岩浆上升过程提供新的约束。这些约束将通过对硅酸盐熔体的相关系和挥发溶解度的高压-高温实验研究得到。将火山穹丘（包括安山岩包地）的自然样品与icdp钻探的实验结果进行比较，将用于了解混合（以及随后可能的脱气）对岩浆强迫的作用以及岩浆上升过程中的动力学过程（动态系统中的脱气、结晶）的作用。