Dynamics of Large Silicic Magma Reservoirs: Combining Geochemical Data and Physical Models on Voluminous Ignimbrites From the San Juan Volcanic Field, Colorado

大型火山爆发是地球内部能量的迷人展示。它们涉及一系列复杂的过程，从地幔和地壳深处的岩浆生成到地球表面热灰和气体的灾难性喷发。火山岩浆在地壳浅层储层中的活动过程对我们理解火山作用和地壳构造至关重要。在这方面，大的无定形不定形物（即，火山碎屑流沉积物）提供了这种岩浆如何与环境相互作用而演化的特殊记录。研究大规模岩浆活动（特别是从地壳演化和大型岩浆库中发生的岩石学过程的角度）的理想地区是圣胡安火山区（科罗拉多，美国）。高产的第三纪岩浆活动（至少有17个大体积的灰流片之间爆发约29.5至26.9马）通过大陆地壳为主的前寒武纪岩性允许一些可能的研究，其中一些将探讨在本proposal.It建议使用大熔结凝灰岩片从圣胡安火山领域的天然实验室的岩浆演化过程。 该小组将联合收割机将地球化学微观分析技术（如电子探针、LA-ICP-MS和微钻-TIMS分析）的结果与岩浆动力学的数值模拟相结合，以更好地了解导致大型灰流凝灰岩成分分带的机制;上地壳条件下地壳同化的动力学;并检查导致大型水库喷发的所有必要条件。除了已发表的关于圣胡安岩浆的地质年代学和地球化学数据外，新的分析数据将用于提供理想的垫脚石，以仔细检查关键岩石单元，并合并岩浆过程的物理和地球化学模型。

Large volcanic eruptions are fascinating displays of our Earth's internal energy. They involve a series of complex processes from magma generation in the mantle and deep crust to the catastrophic outpourings of hot ash and gas on the surface of our planet. The processes by which silicic magma behave in shallow crustal reservoirs are critical to our understanding of volcanism and crustal construction. In that respect, large silicic ignimbrites (i.e., pyroclastic flow deposits) provide an exceptional record of how such magmas evolve in interaction with their environment. An ideal region in which to study large-volume silicic magmatism (especially from perspectives of crustal evolution and petrological processes occurring in large silicic magma reservoirs) is the San Juan volcanic field (Colorado, USA). Highly productive Tertiary magmatism (at least 17 large-volume ash-flow sheets erupted between ~29.5 to 26.9 Ma) through continental crust dominated by Precambrian lithologies allows a number of possible studies, some of which will be explored in this proposal.It is proposed to use large ignimbrite sheets from the San Juan volcanic field as natural laboratories for silicic magma evolution processes. The team will combine results from geochemical micro-analytical techniques (such as electron microprobe, LA-ICP-MS and microdrilling-TIMS analyses) in conjunction with numerical simulations of magma dynamics to better understand the mechanisms leading to compositional zoning in large ash-flow tuffs; the dynamics of crustal assimilation in upper crustal conditions; and examine all necessary conditions leading to eruption of large reservoirs. New analytical data in addition to published geochronological and geochemical data on San Juan magmas will be used to provide the ideal stepping stone for scrutinizing key rock units and merging physical and geochemical models of magmatic processes.