Earth system can be categorized into three parts, solid Earth system, surface Earth system, and Sun-Earth space system. These three subsystems not only have mutual transmission and coupling relationships in both energ...Earth system can be categorized into three parts, solid Earth system, surface Earth system, and Sun-Earth space system. These three subsystems not only have mutual transmission and coupling relationships in both energy and matter but also involve multiple scales from microscopic to macroscopic. Earth system science is characterized by its globality and unity with a holistic view and a systematic view at multiple scales in both space and time. It focuses not only on the physical, chemical and biological interactions between various geospheres but also on the properties, behaviors, processes, and mechanisms of the entire Earth and its spheres. Although significant progress has been made in the study of internal disciplines of these three subsystems,there is still insufficient understanding of their overall behavior and interactions between individuals, thus facing challenges of different types and levels. The solid Earth system is composed of the crust, mantle, and core. Existing observational techniques struggle to penetrate deep into the mantle, making direct observation and data acquisition difficult;the extreme environments within Earth, such as high temperature, high pressure, and strong magnetic fields, also pose great challenges to observational equipment and scientific experiments. The surface Earth system is an open complex mega-system, in which there are complex interactions and feedback mechanisms among its geospheres(such as atmosphere, hydrosphere, biosphere, pedosphere and lithosphere), leading to difficulties in understanding of its overall behavior and long-term evolution. Biological activities have become increasingly significant in affecting the surface Earth system. The coupling between the internal and external Earth systems becomes more complex. Distinguishing and quantifying the impacts of Earth spherical interactions and biological activities on the surface Earth system is a major challenge. The Sun-Earth space system involves multiple physical processes such as solar activity, Earth's magnet展开更多
The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for unders...The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for understanding deep mantle processes. Such high P–T experiments are commonly conducted in a laser-heated diamond anvil cell, producing a multiphase assemblage consisting of 100 nm to submicron crystallite grains. The structures of these lower mantle phases often cannot be preserved upon pressure quenching;thus, in situ characterization is needed. The X-ray diffraction (XRD) pattern of such a multiphase assemblage usually displays a mixture of diffraction spots and rings as a result of the coarse grain size relative to the small X-ray beam size (3–5 lm) available at the synchrotron facilities. Severe peak overlapping from multiple phases renders the powder XRD method inadequate for indexing new phases and minor phases. Consequently, structure determination of new phases in a high P–T multiphase assemblage has been extremely difficult using conventional XRD techniques. Our recent development of multigrain XRD in high-pressure research has enabled the indexation of hundreds of individual crystallite grains simultaneously through the determination of crystallographic orientations for these individual grains. Once indexation is achieved, each grain can be treated as a single crystal. The combined crystallographic information from individual grains can be used to determine the crystal structures of new phases and minor phases simultaneously in a multiphase system. With this new development, we have opened up a new area of crystallography under the high P–T conditions of the deep lower mantle. This paper explains key challenges in studying multiphase systems and demonstrates the unique capabilities of high-pressure multigrain XRD through successful examples of its applications.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.92155306 and L2224031)。
文摘Earth system can be categorized into three parts, solid Earth system, surface Earth system, and Sun-Earth space system. These three subsystems not only have mutual transmission and coupling relationships in both energy and matter but also involve multiple scales from microscopic to macroscopic. Earth system science is characterized by its globality and unity with a holistic view and a systematic view at multiple scales in both space and time. It focuses not only on the physical, chemical and biological interactions between various geospheres but also on the properties, behaviors, processes, and mechanisms of the entire Earth and its spheres. Although significant progress has been made in the study of internal disciplines of these three subsystems,there is still insufficient understanding of their overall behavior and interactions between individuals, thus facing challenges of different types and levels. The solid Earth system is composed of the crust, mantle, and core. Existing observational techniques struggle to penetrate deep into the mantle, making direct observation and data acquisition difficult;the extreme environments within Earth, such as high temperature, high pressure, and strong magnetic fields, also pose great challenges to observational equipment and scientific experiments. The surface Earth system is an open complex mega-system, in which there are complex interactions and feedback mechanisms among its geospheres(such as atmosphere, hydrosphere, biosphere, pedosphere and lithosphere), leading to difficulties in understanding of its overall behavior and long-term evolution. Biological activities have become increasingly significant in affecting the surface Earth system. The coupling between the internal and external Earth systems becomes more complex. Distinguishing and quantifying the impacts of Earth spherical interactions and biological activities on the surface Earth system is a major challenge. The Sun-Earth space system involves multiple physical processes such as solar activity, Earth's magnet
基金the National Natural Science Foundation of China (41574080 and U1530402).
文摘The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for understanding deep mantle processes. Such high P–T experiments are commonly conducted in a laser-heated diamond anvil cell, producing a multiphase assemblage consisting of 100 nm to submicron crystallite grains. The structures of these lower mantle phases often cannot be preserved upon pressure quenching;thus, in situ characterization is needed. The X-ray diffraction (XRD) pattern of such a multiphase assemblage usually displays a mixture of diffraction spots and rings as a result of the coarse grain size relative to the small X-ray beam size (3–5 lm) available at the synchrotron facilities. Severe peak overlapping from multiple phases renders the powder XRD method inadequate for indexing new phases and minor phases. Consequently, structure determination of new phases in a high P–T multiphase assemblage has been extremely difficult using conventional XRD techniques. Our recent development of multigrain XRD in high-pressure research has enabled the indexation of hundreds of individual crystallite grains simultaneously through the determination of crystallographic orientations for these individual grains. Once indexation is achieved, each grain can be treated as a single crystal. The combined crystallographic information from individual grains can be used to determine the crystal structures of new phases and minor phases simultaneously in a multiphase system. With this new development, we have opened up a new area of crystallography under the high P–T conditions of the deep lower mantle. This paper explains key challenges in studying multiphase systems and demonstrates the unique capabilities of high-pressure multigrain XRD through successful examples of its applications.
基金supported by the National Natural Science Foundation of China(42074104,11774015,and U1930401)Youth Interdisciplinary Team of Chinese Academy of Sciences(JCTD2022-16)+3 种基金Youth Innovation Promotion Association of Chinese Academy of Sciences(2020394)Guizhou Provincial 2020 Science and Technology Subsidies(GZ2020SIG)the support from the National Research Foundation of Korea(NRF-2020R1A2C1005236)supported by the National Science Foundation-Earth Sciences(EAR-1634415)。
