NSFGEO-NERC Collaborative Research: Linking geophysics and volcanic gas measurements to contrain the transcrustal magmatic system at the Altiplano-Puna Deformation Anomaly

岩浆穿过地壳的路径尚不清楚——岩浆储存在哪里，在什么条件下会喷发？虽然这个问题具有基本的科学兴趣，但它也直接关系到理解火山系统所造成的危害，这些火山系统显示出活动和动荡的迹象。该项目旨在了解动荡的原因和安第斯山脉中部岩浆储存系统的结构，安第斯山脉是世界上最大的硅部分熔体的地球物理成像区，即Altiplano-Puna岩浆体（或Mush） （APMB）的所在地。该项目涉及美国、英国和玻利维亚的科学家，在玻利维亚的乌图伦库火山收集新的野外测量数据（重力、地面变形、地震、气体通量和成分），并根据新数据开发火山的数值模型。特别是，新的数据将增加对不稳定火山背景活动的有限理解，这对于更好地评估未来火山动荡的危害是必要的——什么是正常的活动，什么应该引起关注？在跨地壳岩浆系统（TCMS）中，岩浆的储存和分异发生在整个地壳柱的几个位置。这一概念革命是由岩石学、地质年代学和地球化学对岩浆储存条件的研究推动的，这些研究表明：(1)许多大型喷发利用了多种熔体来源，(2)大型熔体可能是短暂的特征，(3)由运输熔体携带的晶体在一定的压力和温度下储存。评估和完善目前活跃的TCMS模型的一个关键位置是在APMB，在那里，以玻利维亚的Uturuncu火山为中心，观察到一个直径150公里、持续数十年的大地面变形模式。通过收集和分析新的跨学科领域测量（重力、地面变形、地震、气体通量和成分）和开发三维数值模型，本提案将回答有关APMB TCMS性质的几个突出问题：1。是什么导致了APMB中地壳的变形：岩浆底辟、岩浆和/或挥发物重组引起的上下循环运动，还是别的什么？2. 浅层导电性异常的性质是什么？在多大程度上是部分熔体、热液盐水储层还是成熟矿体？3. 挥发物通过tcm的通量是多少？4. 地壳各向异性在解释地下岩浆管道构造中有多重要？该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The path that magma takes through the crust is not well understood -- where is magma stored and under what conditions will it erupt? While this question is of fundamental scientific interest, it is also directly related to understanding the hazard posed by volcanic systems that are showing signs of activity and unrest. This project seeks to understand the cause of unrest and the architecture of the magma storage system within the central Andes, home to the world's largest geophysically imaged zone of silicic partial melt, the Altiplano-Puna Magma (or Mush) Body (APMB). This project involves scientists in the USA, United Kingdom, and Bolivia to collect new field measurements (gravity, ground deformation, seismic, gas flux and composition) at Uturuncu volcano, Bolivia and develop numerical models of the volcano motivated by the new data. In particular, the new data will add to the limited understand of the background activity at restless volcanoes that is necessary to better assess the hazard of future volcanic unrest -- what is normal activity and what should cause concern?There is a new emerging paradigm of a transcrustal magmatic system (TCMS) where magma storage and differentiation occurs at several locations throughout the entire crustal column. This conceptual revolution is being driven by petrological, geochronological, and geochemical studies of magma storage conditions that show (1) many large eruptions tap multiple melt sources, (2) large melt bodies are probably transient features, (3) crystals carried by the transporting melt have been stored at a range of pressures and temperatures. A key location to assess and refine models of currently active TCMS is at the APMB, where a large ground deformation pattern 150 km in diameter lasting several decades has been observed centered on Uturuncu volcano, Bolivia. By collecting and analyzing new interdisciplinary field measurements (gravity, ground deformation, seismic, gas flux and composition) and developing 3D numerical models, this proposal will answer several outstanding questions about the nature of TCMS at the APMB: 1. What is the cause of deformation in the midcrust at the APMB: a magmatic diapir, cyclic up and down movements from magma mush reorganization involving magma and/or volatiles, or something else? 2. What is the nature of a shallow-seated conductivity anomaly -- to what extent is it partial melt, a hydrothermal brine reservoir, or a mature ore body? 3. What is the flux of volatiles through the TCMS? 4. How important is crustal anisotropy in the interpretation of the subsurface magma plumbing architecture?This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.