Superdeep Diamonds from the Transition Zone and Lower Mantle

GSTDTAP

项目编号	1853521
	Superdeep Diamonds from the Transition Zone and Lower Mantle
	Steven Jacobsen (Principal Investigator)
主持机构	Northwestern University
项目开始年	2019
	2019-02-01
项目结束日期	2022-01-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	435217(USD)
国家	美国
语种	英语
英文摘要	Diamond is a remarkable material for its ultimate physical properties and technological applications. Natural diamonds also reveal physical and chemical processes in the Earth's deep mantle from where there are few direct samples. Mineral inclusions in diamond reflect reactions involving high pressure, high temperature, fluids, melts, and dynamic interactions between the Earth's surface and interior. This project will support technological development to investigate tiny mineral inclusions in diamonds. A new suite of more than 150 diamonds of deep origin, which formed at depths greater than 410 km in the transition zone and the lower mantle, will be investigated. 3D imaging, diffraction, and spectroscopy of the hosted inclusions will be carried out at national X-ray and infrared facilities. Up to a thousand micro-mineral inclusions will be identified and characterized by fast, high-throughput methods. Results of this research will improve our understanding of the mineral diversity in the Earth's interior, with special focus on water and hydrous phases. The goal is to reveal the mechanisms by which water recycles between the crust and mantle through plate tectonics, a process at the origin of numerous natural hazards. This project will foster collaboration with two local high-school teachers to introduce a geophysics curriculum to their physics courses. It will also promote the training of several graduate students for future careers in academia, federal agencies, industry, and the national laboratories. The high strength and stability of diamond make it a perfect vessel for transporting minerals and geochemical information from the deep mantle to the surface as part of the crust-mantle carbon cycle. This study will examine a new suite of superdeep diamonds from Juina, Brazil, which host mineral inclusions from the transition zone and lower mantle. One of the major challenges pertains to determining the depth origin of the diamonds which often lack a complete suite of mineral inclusions to pinpoint their formation conditions. Up to a thousand inclusions will be analyzed potentially promoting the discovery of new mineral phases and providing information about how deeply water is transported into the mantle. New micro-analysis techniques will increase the rate and decrease the size of inclusions that can be studied, thus broadening the database of mantle mineralogy. Spectroscopic methods will probe various types of atomic-scale defects in diamonds as tracers for their depth of origin. Separately, the sound velocity of diamond will be measured at high pressure in all directions of the structure to determine diamond elastic properties. This will improve the geophysical modeling of seismic wave velocity in the deep, crustal roots below continents. Other experiments will examine the decompression behavior of hydrous minerals at upper mantle temperatures to elucidate diamond ascent pathways. Ultimately this research will improve and potentially modify the textbook picture of the structure and dynamics of Earth's interior. 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.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/213336
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Steven Jacobsen .Superdeep Diamonds from the Transition Zone and Lower Mantle.2019.