Influence of Earth's rotation on the differentiation of a terrestrial magma ocean

• Applicant: Professor Dr. Ulrich Hansen
• Subject Area: Geophysics
• Term: from 2015 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 276785248

In a later stage of its accretion Earth experienced one or more giant impacts of mars-sized impactors, causing the formation of one or several deep magma oceans of global extent. The crystallization of these magma oceans is of key importance for the chemical structure of Earth and for the onset of plate tectonics. Due to the fast rotation of early Earth and small magma viscosity, rotation probably had a profound effect on differentiation processes. However, nearly all previous studies neglected the effects of rotation. In our previous work, obtained in a unit square, we showed that rotation has an important influence on magma ocean dynamics. To our knowledge there is currently no other model available allowing to include rotational forces.Within the scope of this proposal we plan to extend our developed method to a realistic spherical geometry in order to investigate the influence of rotation on the crystallization of a terrestrial magma ocean in a spherical shell. Further, we will study magma ocean-relevant rheology and the interaction between different mineral phases. Another key aspect will be the influence of different types of atmospheres at the top of a rotating and vigorously convecting magma ocean, which we plan to study by applying different boundary conditions at the top. To our knowledge similar investigations have not yet been carried out by other groups.We feel that the proposed work can provide fundamentally new insights into differentiation processes of a terrestrial magma ocean and thus shed light on the creation and survival of compositional reservoirs. Especially the origin, distribution and persistence of heterogeneities with respect to large low shear velocity provinces (LLSVP) will be investigated. These structures are important for the onset and evolution of plate tectonics as well as for the time-history of the magnetic field, thus being closely linked to the Earth's habitability.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1833: Building a Habitable Earth