American Association for the Advancement of Science (AAAS)
Researchers report that high-pressure perovskite silicate perovskite (CaSiO3) was first identified as a natural mineral from the lower Earth's mantle. The newly discovered crystalline compound, named davemaoite by the author, was discovered as an inclusion trapped in a deep diamond that formed under high pressure and high temperature more than 660 kilometers below the earth's surface. Davemaoite was named in memory of Ho-kwang (Dave) Mao, a famous experimental high-pressure geophysicist, and was recognized as a new mineral by the International Mineralogy Association. According to Oliver Tschauner and colleagues, perovskite silicate perovskite (CaSiO3) is one of the most important geochemically important minerals in the lower mantle, mainly because it concentrates elements that are incompatible with the upper mantle, including rare earth elements. And the contribution of radioactive isotopes to the mantle heat. Despite decades of theory, no one has successfully extracted high-pressure phase silicates from the Earth’s lower mantle, mainly because they cannot retain their mineral structure after being removed from the high-pressure and high-temperature environment. . The only other high-pressure phase silicate mineral Bridgmanite identified in nature was found in a highly impacted meteorite. In this study, Tshauner et al. The synchrotron X-ray diffraction was used to identify and characterize the inclusions of Davymite in the deep diamond. They show the ability to accommodate multiple elements in their structure, including potassium, thorium and uranium-the three main heat-generating elements. The research results support the existence of compositional heterogeneity in the lower mantle, and given the overall abundance of minerals, indicate that rhinestones may affect the heat production in the deep mantle. "The work of Tschauner et al. Through careful searching of deep-source diamonds or highly shocked meteorites has inspired people to find other difficult and high-pressure phases in nature," Ying Weifei wrote in a related view. "This kind of direct sampling of the inaccessible lower mantle will fill a gap in our knowledge of the chemical composition and heterogeneity of the Earth's entire mantle."
For reporters interested in trends, several past scientific publications featuring the work of Oliver Tschauner and others have introduced discoveries related to minerals in the lower mantle, including a report in November 2014, Describes the discovery of a "bridge stone" in a shocked meteorite-the only other high-pressure mineral that has been confirmed in nature.
In addition, the March 2018 report of Tschauner et al. Use Deep Earth Diamonds to discover the inclusion of Ice-VII-the cubic crystal form of ice, which is formed when water is trapped and subjected to extremely high pressure.
Davymite and CaSiO3-perovskite are found in the lower mantle as minerals
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Science Press Package Team American Association for the Advancement of Science/AAAS scipak@aaas.org
Oliver Tschauner University of Nevada, Las Vegas Oliver.tschauner@unlv.edu
Fei Yingwei Carnegie Institute of Science yfei@carnegiescience.edu
American Association for the Advancement of Science (AAAS)
Copyright © 2021 American Association for the Advancement of Science (AAAS)
Copyright © 2021 American Association for the Advancement of Science (AAAS)