Rocky mantle and metallic iron core building Earth’s internal structure is the largest stratification universally found in terrestrial planets. The chemical composition of the mantle, which accounts for 80% of the Earth in volume, and the light elements contained in the core, which accounts for the remaining 20%, remain unresolved for more than 60 years. Vigorous convection has been inferred in the core-mantle boundary layer from seismology, while geochemistry has insisted that stable regions preserving primordial signatures of the Earth formation have been present over a period of even 4.6 billion years. Geophysical and geochemical pictures of Earth’s deep interior are therefore incompatible. In addition, although the mantle convection is driven by the radioactive decay heat as well as the heat conduction from the core, the type and amount of heat source elements in the mantle still remain unclear. This leads to our insufficient understanding of the past and future thermal evolution of the Earth’s interior.
These unresolved problems in deep Earth science can be elucidated by considering the core and mantle as a single coupled system and by clarifying their interaction. Experiments at high pressure and high temperature corresponding to the center of the Earth nowadays become possible, and high-precision geophysical observation, precise geochemical analysis, first-principles quantum mechanical calculations, etc. have also greatly developed. Furthermore, practicality of geoneutrino observation for constraining the distribution of radioactive elements in the deep Earth is being enhanced. By integrating these unique scientific fields of experiment, chemical analysis, observation and theory, a new research direction to understanding the core-mantle interaction and its coevolution could be opened.
In this program, we solicit applications for research grants (KAKENHI) that reinforce five research units (A01: Physical property measurement, A02: Geochemical analysis, A03: Geophysical observation, A04: Theory and computation, and B01: Integration analysis). The last one (B01) is composed only of open researches selected by this application and will perform crossdisciplinary study connecting multiple research units. Proposals in which advanced technologies and/or out-of-box collaborative research structure in this program will be actively utilized are most welcome.
