On the physics of crystal-rich mush

火山下发生的过程、火山喷发和其他形成地壳的看不见的过程存在很大的不确定性。喷发物质的化学成分和相关的“冰冻”岩石体都表明，这些岩浆（熔融岩石）的自然状态是一种糊状或富含晶体的物质。理解火山和化学成分多样性产生过程的一个障碍是，人们对这些糊状物的物理行为了解得很少。本研究的目的是在新的细节上阐明发生在晶体浆液中的物理过程是如何控制火山和深部系统的。这项工作更广泛的影响是，它将提高我们理解、预测和沟通危险的能力，并解释为什么某些过程具有特定的时间尺度。它还将把材料科学的新概念引入到地质过程的研究中，培养学生广泛应用的解决问题的新技能。这项研究工作是美国和法国五个机构共14名研究人员合作的一部分。研究目的是通过结合新颖的、联系的实验和数值模拟技术来描述和合理化岩浆泥的行为。这将是高分辨率数值和实验室实验第一次以一种初步协调的方式使用相同规模的天然材料。实验工作的具体研究成果提供了糊状物描述的运动学要素：局部和系统结构（由图像分析计算的张量表示）和体流变学。数值实验提供了实验室实验无法获得的信息：力张量和结构。将这两种描述结合起来，就产生了一个统一的、可扩展的框架，可以揭示对岩浆行为的控制，而无需对各种岩浆成分和条件进行特别假设。实验工作既包括高压设备，格里格斯钻机，也包括更中等压力的帕特森压力机。因此，该项目将探索从莫霍面到近地表的压力范围，并共享描述元素。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。

There is great uncertainty about the processes that occur under volcanoes, yielding eruptions and other unseen processes that form the Earth's crust. Both the chemical composition of erupted materials and the related 'frozen' bodies of rock, suggests that the natural state of these magmas (molten rock) is a mushy, or crystal-rich material. An obstacle to understanding the processes that produce the diversity in volcanoes and chemical compositions is that there is only a poor understanding of the physical behavior of these mushes. The objective of this research is to illuminate in new detail how the physical processes occurring in crystal mush can control volcanic and plutonic systems. The broader impacts of this work are that it will enhance our ability to understand, anticipate and communicate hazards and to explain why certain processes have particular timescales. It will also bring new concepts from material science into the study of geological processes, and train students in new problem solving skills of wide application.This research effort is one part of a collaboration involving a total fourteen researchers at five institutions, in the USA and France. The research objective is to describe and rationalize the behavior of magma mush by a combination of novel, linked experimental and numerical modeling techniques. This will be the first time that high resolution numerical and laboratory experiments will be employed in an initially coordinated fashion using natural materials at the same scale. The specific research products from the experimental work provide kinematic elements of mush description: local and system fabric (expressed by their tensors calculated by image analysis) and bulk rheology. The numerical experiments provide information unavailable from the lab experiments: force tensors and fabric. Combining these two descriptions yields a unified, extensible framework to reveal the controls on mush behavior without ad hoc assumptions across a wide variety of magmatic compositions and conditions. The experimental work includes both high-pressure apparatus, The Griggs rig, as well as more moderate pressure, the Paterson press. Thus the project will explore a pressure range from the Moho to the near surface with shared elements of description.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.