HYDROTHERMAL CONTROLS ON CALDERA EXPLOSIVITY

火山口爆炸的热液控制

• 批准号: NE/X01519X/1
• 负责人: Isobel Yeo
• 金额: $ 128.9万
• 依托单位: NATIONAL OCEANOGRAPHY CENTRE
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX01519X%2F1
• 关键词: HYDROTHERMAL; CONTROLS; CALDERA; EXPLOSIVITY

Almost all active caldera volcanoes host hydrothermal systems that circulate a mixture of seawater, meteoric water and magmatic fluids through the subsurface geology to seeps or vents on the seafloor. These fluids can explosively interact with magma in volcanic eruptions and can change the physical properties of their host rocks, influencing both the likelihood of eruptions occurring and their explosivity. The nature of these interactions is poorly understood, including how fluid flow changes during periods of magmatic intrusion, how the hydrothermal system connects magmatic fluids to the surface and the spatial distribution and extent of alteration/mineralisation. While we know hydrothermal fluid flow plays an important role in modulating eruption dynamics, as long as these fundamental knowledge gaps exist it is impossible to forecast, with any degree of accuracy, what this effect will be which makes understanding hazards and impacts in eruption scenarios difficult. In this proposal we will combine novel controlled source electromagnetic mapping of porosity and permeability, with passive seismic mapping of hydrothermal fluid flow in the shallow subsurface, constrained by heat flow measurements and surface and subsurface sampling to characterise the porosity and permeability of the Santorini hydrothermal system. Santorini has been selected as the ideal natural laboratory to test these relationships because it is exceptionally well characterised geophysically and geologically, has a diversity of hydrothermal vents and has experienced recent activity which can be used to test modelling. We will quantify how magmatic fluids are partitioned between vents to identify the primary pathways for magmatic volatile escape, and quantify the impact hydrothermal mineralisation has had on the physical strength of the seafloor. Once we have a full picture of the system in its current state we will use mapping, fluid inclusions, mineralogy and the sedimentary record to establish how vent locations, subsurface fluid pathways, and fluid fluxes, temperatures and chemistries responded to the 2011/12 period of unrest. These data will be used to constrain the boundary conditions for a hydrothermal system model, which can be used to predict how the system will respond to future periods of intrusion both at Santorini and at other caldera systems around the world. This project will provide a step change in our understanding of hydrothermal interactions with volcanoes and our ability to predict their response to changes in the magmatic system. This has implications not just for understanding volcanic eruptions, but also for understanding metal and volatile fluxes from the mantle to the ocean and atmosphere, the development of economic metal deposits in these systems, the impact on ecological communities of intrusive and extrusive volcanic events, geothermal energy production, and for hazard forecasting and mitigation. The project will push the frontiers of knowledge by combining cutting edge geophysical and geochemical techniques to produce a model of a caldera hydrothermal system at a resolution previously not possible, and by developing modelling tools that would allow the application of these findings to other systems. The project is ambitious but achievable and benefits from a large team of international expert proponents, partnerships with other large international projects and high-quality pre-existing data upon which to build.

几乎所有的活火山都有热液系统，海水、大气水和岩浆流体的混合物通过地下地质循环到海底的渗漏或喷口。这些流体可以在火山喷发时与岩浆发生爆炸性的相互作用，并可以改变其宿主岩石的物理性质，从而影响火山喷发的可能性和爆炸性。人们对这些相互作用的性质知之甚少，包括岩浆侵入期间流体流动如何变化，热液系统如何将岩浆流体连接到地表，以及蚀变/矿化的空间分布和程度。虽然我们知道热液流动在调节喷发动力学方面发挥着重要作用，但只要这些基本知识差距存在，就不可能以任何程度的准确性预测这种影响将是什么，这使得理解喷发情景中的危险和影响变得困难。在这项提议中，我们将结合新颖的孔隙度和渗透率受控震源电磁测图，以及受热流测量和地表和地下取样约束的浅层地下热液流动的被动地震测图，来表征圣托里尼热液系统的孔隙度和渗透率。圣托里尼被选为测试这些关系的理想天然实验室，因为它具有非常好的地球物理和地质特征，具有多样化的热液喷口，并且最近经历了可用于测试模型的活动。我们将量化岩浆流体在喷口之间的分配方式，以确定岩浆挥发性物质逃逸的主要途径，并量化热液矿化对海底物理强度的影响。一旦我们对该系统的当前状态有了全面的了解，我们将利用测绘、流体包裹体、矿物学和沉积记录来确定喷口位置、地下流体路径以及流体流量、温度和化学成分对2011/12年度动乱期间的反应。这些数据将被用来约束热液系统模型的边界条件，该模型可用于预测系统将如何应对圣托里尼和世界各地其他火山口系统未来的入侵时期。该项目将使我们对与火山的热液相互作用的理解以及我们预测火山对岩浆系统变化的反应的能力发生重大变化。这不仅对于了解火山喷发，而且对于了解从地幔到海洋和大气的金属和挥发性通量、这些系统中经济金属矿藏的开发、侵入和喷发火山事件对生态群落的影响、地热能生产以及灾害预测和减灾都有影响。该项目将把尖端的地球物理和地球化学技术结合起来，以以前不可能达到的分辨率制作火山口热液系统模型，并开发能够将这些研究结果应用于其他系统的建模工具，从而推动知识的前沿。该项目雄心勃勃，但可以实现，受益于国际专家支持者的庞大团队、与其他大型国际项目的伙伴关系以及可供建立的高质量先前存在的数据。