Thermal convection modeling of the evolution of the earth core

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Abstract

We present a purely thermal convection 2D model of the Earth’s liquid core, occurring on the background of the secular cooling of the planet. The model includes equations of thermal convection in the Boussinesq approximation and the Coriolis force. Metallic iron with 0.9 wt. % Н is chosen for the core composition. The results of modeling show that large vortexes, the 2-D analogues of Taylor columns, are formed in the liquid core prior to crystallization, which might be responsible for the early Earth magnetic field. The early stages of the solid core crystallization are characterized by a chaotic and shapeless growth. Continuing growth of the solid core results in rearrangement of the convection structure decreasing its average velocity but increasing heat flow at the core-mantle boundary due to increased amount of heat of crystallization. The solid core reaches its present size in 0.5 Gy. Averaged temperature profile of the modern liquid core differs significantly from the adiabatic.

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About the authors

L. Ya. Aranovich

Institute of Geology of ore deposits, petrography, mineralogy and geochemistry Russian Academy of Sciences

Author for correspondence.
Email: lyaranov@igem.ru

Academician of the RAS

Russian Federation, Moscow

V. D. Kotelkin

Lomonosov Moscow State University

Email: vyacheslav.kotelkin@math.msu.ru
Russian Federation, Moscow

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2. Fig. 1. Temperature (T) and vorticity (Ω) in the core before crystallization begins.

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3. Fig. 2. Successive stages of core crystallization from early (panel a) to late (panel m). The modern size of the solid core corresponds to panel i

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4. Fig. 3. Temperature (T) and vorticity (Ω) in the liquid core of the modern configuration

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5. Fig. 4. (left) – growth of the inner core ( , green), heat flow from the core to the mantle ( , blue) and average convection velocity ( , brown); (right) – average temperature profile in the core (solid red curve) compared to the adiabatic one according to [9] (dashed line)

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