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意义，但它也直接关系到对火山系统构成的危险的理解，这些火山系统显示出活动和动荡的迹象。该项目旨在了解动乱的原因和安第斯山脉中部岩浆储存系统的架构，安第斯山脉是世界上最大的硅质部分熔融地球物理成像带-阿尔蒂普诺-普纳岩浆(或Mush)天体(APMB)的所在地。该项目邀请美国、英国和玻利维亚的科学家在玻利维亚乌图伦库火山收集新的现场测量数据(重力、地面变形、地震、气体流量和成分)，并根据新数据建立火山的数值模型。特别是，新的数据将增加对不安的火山背景活动的有限了解，这对于更好地评估未来火山动荡的危险是必要的--什么是正常活动，什么应该引起关注？跨地壳岩浆系统(TCMS)的一个新的范例，其中岩浆储存和分异发生在整个地壳柱的几个位置。对岩浆储存条件的岩石学、地质年代学和地球化学研究表明，(1)许多大型喷发利用多个熔体来源，(2)大型熔体可能是瞬时特征，(3)输送熔体携带的晶体在一定的压力和温度范围内储存。评估和改进目前活跃的TCMS模型的一个关键地点是APMB，在那里观察到了以玻利维亚乌图伦库火山为中心、直径150公里、持续数十年的大地面形变模式。通过收集和分析新的跨学科野外测量数据(重力、地面形变、地震、气体流量和成分)以及发展3D数值模型，这一建议将回答关于APMB的TCMS性质的几个悬而未决的问题：1.APMB中地壳变形的原因是什么：岩浆底辟、涉及岩浆和/或挥发分或其他物质的岩浆泥重组的周期性上下运动？2.浅层电导率异常的性质是什么--它在多大程度上是部分熔融、热卤水储集层、或者是成熟的矿体？3.挥发分通过TCMS的流量是多少？4.地壳各向异性在解释地下岩浆管道结构方面有多重要？这一裁决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智力优势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.