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

NSFGEO-NERC：合作研究：将地球物理学和火山气体测量联系起来，以约束高原-普纳变形异常处的穿地壳岩浆系统

• 批准号: 1757415
• 负责人: Tobias Fischer
• 金额: $ 23.34万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1757415&HistoricalAwards=false
• 关键词: NSFGEO; NERC; Collaborative; Research; Linking

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.

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。该项目旨在了解动荡的原因和安第斯山脉中部的岩浆储存系统的结构，这里是世界上最大的部分熔融的火山成像区，即高原-普纳岩浆（或糊状物）体（APMB）。 该项目涉及美国、联合王国和玻利维亚的科学家，以收集玻利维亚的Uturuncu火山的新的实地测量数据（重力、地面变形、地震、气体通量和成分），并根据新数据建立火山的数字模型。 特别是，新的数据将增加对不平静火山的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？有一个新的出现的范例，穿壳岩浆系统（TCMS）的岩浆储存和分异发生在几个地点在整个地壳柱。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？该奖项反映了NSF的法定使命，并被认为是值得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的支持。