Collaborative Research: Density and structure of silicate liquids under deep mantle conditions

GSTDTAP

项目编号	1620548
	Collaborative Research: Density and structure of silicate liquids under deep mantle conditions
	Yanbin Wang
主持机构	University of Chicago
项目开始年	2016
	2016-07-01
项目结束日期	2019-06-30
资助机构	US-NSF
项目类别	Continuing grant
项目经费	110000(USD)
国家	美国
语种	英语
英文摘要	Silicates, the major constituents of Earth's outer crust and rocky mantle layers, melt at very high temperatures, especially at deeper depths. Liquid forms of silicates played a pivotal role in the early evolution history of planet Earth and continue to influence dynamic processes in present day. The early Earth was most likely molten after the formation process. As the Earth cooled off, liquid silicates solidified and crystals of particular compositions formed at various stages of the cooling process, defining the composition structure of the Earth as we have today. Giant amounts of magmas are ascending from present-day mid-ocean ridges, a process closely related to plate tectonics. The cooling products of these magmas form the ocean floors. Volcanic activities over the globe change the environment and endangering human lives. Understanding the dynamics and thermodynamics of these processes requires knowledge of density, viscosity, and structure of silicate liquids over a wide range of pressure conditions corresponding to the Earth's interior. Efforts for obtaining such knowledge have been impeded by technical challenges in the past. To overcome the technical challenges, the investigators have developed a series of synchrotron-based techniques for studying density, compressibility, and structure of silicate liquids under high pressure and temperature conditions. This research will support the training and mentoring of a graduate student and post doc, and will provide support to early career scientists. The investigators propose to study structure-density relations of liquids with selected compositions in the system Na2O-CaO-MgO-FeO-Al2O3-SiO2 to cover major components of mafic to ultramafic liquids relevant to deep mantle melting, by combining advanced techniques using large-volume presses and synchrotron radiation. Structure data will be collected in the Paris-Edinburgh press to 20 GPa and 2500 K. Density will be determined using both in-situ X-ray absorption and ex-situ sink/float techniques. To complement density measurements, sound velocities of selected low-viscosity liquid compositions will be measured using ultrasonic interferometry in a double-stage multianvil press. With these data the team will examine the link between structure and density/compressibility across the pressure range where tetrahedral-to-octahedral coordination change of network formers (Si and Al) occurs. This work will provide vital experimental constraints on modeling liquid compression at deep mantle conditions, by (1) gaining insights into structural evolution of silicate liquids through coordination changes over the pressure range covering the upper mantle, transition zone, and the top of the lower mantle (2) obtaining data on density and acoustic velocity through the coordination transition in liquids, and (3) establishing new equations of state for silicate liquids incorporating structural information, to enable better prediction of liquid density under deep mantle conditions.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/69715
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Yanbin Wang.Collaborative Research: Density and structure of silicate liquids under deep mantle conditions.2016.