Calcium in Bridgmanite in the Deep Mantle

火山活动，比如今天在夏威夷和不久前在黄石公园看到的，都与来自地球内部深处的热量有关。虽然地震研究已经确定了一些大规模的候选结构在地幔深处，可以代表热源或材料，以养活这些大型火山中心，很少有人知道这些结构的起源和性质。 在这个项目中，该团队将调查地球深部地幔中主要矿物的可能成分变化，以便更好地了解深部地幔中可能影响我们星球表面变化的全球尺度结构的性质。 预计在该项目中进行的实验将导致推进我们对根深蒂固的火山作用的形成及其演变的认识。 这种知识在一系列专题中很重要，包括评估某些类型的自然灾害和深入了解导致地球形成为一个行星的过程。该项目将支持亚利桑那州立大学的本科生研究，为对地球科学感兴趣的学生提供实验室研究机会。初步的实验表明，Ca，钙，溶解成bridgmanite（下地幔的主要矿物）在压力-温度条件下的深部地幔。在本项目中，计划测量Ca进入硼镁石晶体结构的压力-温度条件。 该研究的另一个目标是测量含钙桥镁石的物理性质，以与地震识别的大规模地幔结构（如大低剪切速度省）的性质进行比较。拟议的实验包括在高压-温度下的原位X射线测量和使用电子显微镜对回收样品进行化学分析。 由于含钙矿物在下地幔对生热元素的储存能力中起着重要作用，因此本研究项目有望填补我们对深部地幔中生热元素如何在不同地球化学结构中分布的认识空白。

Volcanic activity, such as that seen in Hawaii today and Yellowstone in the recent past, are linked to heat coming from deep in the Earth's interior. Although seismic studies have identified a few large scale candidate structures in the deep mantle that could represent the source of heat or material to feeds these large volcanic centers, little is known about the origin and nature of those structures. In this project, the team will investigate probable compositional changes in the dominant mineral in the Earth's deep mantle, in order to better understand the nature of the global-scale structures in the deep mantle that could affect our planet's changing surface. It is expected that the experiments to be conducted in this project will result in advancing our knowledge of the formation of deeply rooted volcanism and their evolution. Such knowledge is important in a range of topics that include assessing some types of natural hazard and providing insights into the processes that led to the formation of the Earth as a planet. The project will support undergraduate research at Arizona State University, providing laboratory research opportunities for students interested in the geosciences. Preliminary experiments suggest that Ca, Calcium, dissolves into bridgmanite (the dominant lower mantle mineral) at the pressure-temperature conditions of the deep mantle. In this project, it is planned to measure the pressure-temperature conditions where Ca enters into the crystal structure of bridgmanite. An additional goal of the study will be to measure the physical properties of Ca-bearing bridgmanite to compare with the properties of the seismically identified large scale mantle structures, such as Large Low Shear Velocity Provinces. The proposed experiments include in situ X-ray measurements at high pressure-temperature and chemical analysis of the recovered samples using electron microscopy. Because Ca-bearing minerals play an important role in the storage capacity of the lower mantle for heat producing elements, this research project is expected to close a gap in our knowledge of how heat producing elements are distributed among different geochemical structures in the deep mantle.