EAR-PF: Diffusion of water in clinopyroxene

伊丽莎白·费里斯博士被授予NSF地球科学博士后奖学金，在哥伦比亚大学拉蒙特-多尔蒂地球研究所开展研究和教育计划。本研究将探讨水在单斜辉石矿物群中的扩散，特别强调铝、钛和铁的影响。该项目的更大目标是开发一种新的工具来确定地球表面附近岩浆的上升速度。准确地量化这个速率是很重要的，因为物理模型表明上升速率在很大程度上控制了火山爆发的活力。将进行两组实验。首先，将一组天然单斜辉石脱水，并测量它们的扩散剖面。这种方法允许对广泛的自然系统进行研究，并与以前以类似方式进行的实验建立了重要的联系。第二，富铝和水的单斜辉石将被合成，并在高压下与熔体平衡。然后将该系统减压，导致熔体和辉石脱水。这个实验将需要大量的准备工作，但难度的增加被密切模拟晶体生长、结合水、这项研究将测试一种新的分析技术，用于测量火山爆发物理模型的核心参数，并将提供对研究非常有用的数据。地幔的水收支，这在行星到构造尺度上都很重要。此外，费里斯博士将共同组织一个地球动力学演讲系列和一个关于地质系统扩散的研究生研讨会。

Dr. Elizabeth Ferriss has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the Lamont-Doherty Earth Institute, Columbia University. This study will investigate the diffusion of water in the clinopyroxene mineral group, with particular emphasis on the effects of aluminum, titanium, and iron. The larger goal of the project is to develop a new tool to determine the ascent rate of magma near the surface of the Earth. Accurately quantifying this rate is important because physical models suggest that the ascent rate largely controls the vigor of volcanic eruptions. Two sets of experiments will be conducted. First, a set of natural clinopyroxenes will be dehydrated, and their diffusion profiles will be measured. This approach allows the investigation of a wide range of natural systems and creates an important link with previous experiments that were conducted in a similar way. Second, aluminum- and water-rich clinopyroxene will be synthesized and equilibrated with a melt at high pressure. This system will then be decompressed, resulting in dehydration of both the melt and the pyroxenes. This experiment will require a substantial amount of preparation, but the increase in difficulty is offset by the value of closely simulating the natural processes experienced by crystals as they grow, incorporate water, and dehydrate upon decompression.This study will test a novel analytical technique for measuring a parameter that is central to physical models of volcanic eruptions and will also provide data that will be highly useful for investigating the mantle's water budget, which is important at the planetary to tectonic scale. In addition, Dr. Ferriss will co-organize both a geodynamics speaker series and a graduate seminar on diffusion in geological systems.