People--Institute of Geochemistry Chinese Academy of Sciences

1.High temperature and pressure experimental geochemistry
2.Mineralogy, high temperature and pressure experimental mineralogy, and genetics mineralogy
3.The migration and distribution of Uranium (U) and thorium (Th) in the Earth's interior and the related geodynamic significance. Based on the principles of geochemistry, we established the migration and distribution patterns of U and Th in the Earth's interior (Bao and Zhang, 1998). We suggested that during Earth’s accretion stage, highly reducing conditions were prevailing within the Earth’s deep interior, which would lead heat-producing elements U and Th to enter the Earth’s core. Currently, some of these U and Th are still in the Earth's liquid outer core. The heat released from these elements has been part of the energy in maintaining the outer core in a liquid state. U and Th in the core and within the Earth’s deep interior would have gradually been oxidized by water and oxidative volatile compounds, and migrated upward to the asthenosphere position. In this position, they would have accumulated to a relative high level and can be important contributors to the formation of an asthenosphere, or a U, Th rich sphere (Bao and Zhang, 1998; Bao, 1999). Heat produced by U and Th can lower the viscosity there; consequently, the overlying oceanic plates can shift. Therefore, a plate tectonics system can be developed on Earth. This makes Earth different from other terrestrial planets (Bao, 2006). The exploration of U and Th distribution in the Earth's interior is still difficult. High temperature and pressure experimental geochemistry of U and Th is one of the methods, but it hasn’t made a lot progress thus far. Physicists are using geoneutrino detecting techniques to explore U and Th distribution in the Earth's interior (http://www.nu.to.infn.it/Geo-eutrinos/) However, current techniques are unable to determine the direction and distance that an anti-neutrino travels from. Therefore, we are unable to identify whether a neutrino comes from U and Th in the crust, mantle or core. Consequently, current results obtained through these studies are geochemical model-dependent, and still speculative. On the other hand, the latest findings through using GPS data indicate that the temperature of the asthenosphere may be about 300 degrees Celsius higher than the global average at those depths.(Ito and Simons, 2011, Science 332: 947-951). These results can be explained well using our hypothesis that the asthenosphere is a U and Th rich sphere (the details can be found in the papers in the selected publication).