NSFGEO-NERC: Linking geophysics and volcanic gas measurements to constrain the transcrustal magmatic system at the Altiplano-Puna deformation anomaly

岩浆穿过地壳的路径还不太清楚--岩浆储存在哪里，在什么条件下会喷发？虽然这个问题具有根本的科学意义，但它也直接关系到了解正在显示活动和动荡迹象的火山系统所构成的危险。这一建议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，这里是世界上最大的岩浆部分熔融的热成像区，即高原-普纳岩浆（或糊状物）体（APMB）的所在地。这一概念革命是由岩石学、年代学和地球化学对岩浆储存条件的研究所推动的，这些研究表明：（1）许多大的喷发都有多个熔体来源，（2）大的熔体可能是短暂的特征，（3）运输熔体所携带的晶体已经储存在一定的压力和温度范围内。评估和完善目前活跃的TCMS模型的一个关键位置是在APMB，在那里观察到一个大的地面变形模式，直径150公里，持续几十年，以玻利维亚的Uturuncu火山为中心。通过收集和分析新的跨学科现场测量（重力，地面变形，地震，气体通量和成分）和开发3D数值模型，该提案将回答有关APMB TCMS性质的几个突出问题：1。APMB中地壳变形的原因是什么：岩浆底辟，岩浆泥重组引起的周期性上下运动，包括岩浆和/或挥发物，还是其他？2.浅部电导率异常的性质是什么--在多大程度上是部分熔融、热液卤水储层或成熟矿体？3.挥发物通过TCMS的通量是多少？4.地壳各向异性在解释地下岩浆管道结构中有多重要？我们提出了一个多参数的研究，以测试在中央安第斯山脉的TCMS的具体方面，可以广泛适用于其他TCMS目前活跃在世界上和地质记录。使用由美国NSF和英国NERC资助的密切协调的国际地球物理和地球化学方法，我们将测试和改进地面变形的可能原因，更好地约束浅层结构，确定变形是否仍在发生，并对通过系统的挥发性通量进行首次测量。

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 proposal 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).The new paradigm of a transcrustal magmatic system (TCMS) where magma is stored and undergoes chemical changes occurs at several locations throughout the entire crust. 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?We propose a multi-parametric study to test specific aspects of the TCMS in the central Andes that could be broadly applicable to other TCMS currently active in the world and in the geologic record. Using a closely coordinated international geophysical and geochemical approach with funding from both the US NSF and UK NERC, we will test and refine the possible cause of the ground deformation, better constrain the shallow structure, determine whether deformation is still occurring, and make the first measurements of the volatile flux through the system.