On theoretical and numerical modeling of the core-mantle thermal-chemical coupling: Review and perspective view

Abstract

Introduction: On the core-mantle thermal and chemical coupling in terms of the long-term evolution of Earth’s mantle and core, there are mainly two approaches for explaining the magnetic evolution provided from paleomagnetic data [1] and heat budget across the Earth [2]. They are based on numerical mantle convection simulations and parameterized mantle convection model imposing the bottom thermal and chemical boundary conditions at the core-mantle boundary. Parameterized approach: Owing to the great progress on the heat transfer in the deep planetary interior so that may include the heat transport by partial melting [3], it is available to access the coremantle evolution wit semi-analytical approach rather than to use a massively parallel computing. Recent, investigations have been pointed out that the heat transfer across the core-mantle boundary could range up to 20 TW and the age of the inner core seems to be around 500 Myrs or younger, which seems to be consistent with interpretations of paleomagnetic data [4]. Massively parallel computing of mantle convection simulations: However, the parameterized approach could not be addressed for various complicated processes expected in the global-scale mantle dynamics modeling. For instance, the mantle dynamics associated with phase transition and extremely variable viscosity can be only addressed in numerical mantel convection models. In this modeling approach, the coupled core-mantle evolution seems to be influenced from the onset timing of plate-like behavior that is generated by the yield criteria of oceanic lithosphere [5]. Incorporating into the chemical evolution of Earth’s core: In the recent accomplishment of semianalytical model of thermal and chemical evolution of the Earth’s core [6], the chemical diffusive processes may be played for the significant role in thermal and magnetic evolution of the Earth’s core. Moreover, the chemical evolution associated with the inner core growth may also be greatly important for the thermal and magnetic evolution of Earth’s core [7]. Regarding the recent mineral physics accomplishments, the dissolution processes of magnesium or silicon seem to have a great impact to the dynamo actions in the early Earth [8] [9] and pointed out by thermal evolution model [10]. Synthesis and perspectives: In this presentation, I would provide the current status of core-mantle coupling research in terms of long-term evolution of thermal, chemical and magnetic evolution so that can be explained for the geophysical observations, paleomagnetic and mineral physics interpretations using two modeling approaches: 1. Semi-analytical parameterized mantle convection and 2. Massively parallel computing of mantle convection simulations. At the end of presentation, I will provide the future direction of coupled evolution of core-mantle dynamics with both mantle convection and geodynamo simulations that has been provided for the preliminary results [11]. References: [1] Biggin, A. J., et al., Nature 526 (2015). [2] Jaupart, C., et al. Treatise on Geophysics 7 (2007). [3] Driscoll, P., and D. Bercovici, Phys. Earth Planet. Int. 236 (2014). [4] Biggin, A., J., Nature Geoscience 1 (2008). [5] Nakagawa, T., and Tackley, P. J., G-cubed 16 (2015). [6] [7] Labrosse, S., C. R. Geoscience 346 (2014). [8] Badro, J., et al., Nature 536 (2016). [9] Hirose, K., et al., Nature 543 (2017). [10] O’Rourke, J., and Stevenson, D., Nature 529 (2016). [11] Olson, P., et al., Phys. Earth Planet. Int. 214 (2013).