Thermal convection modeling of the evolution of the earth core

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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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作者简介

L. Aranovich

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

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Email: lyaranov@igem.ru

Academician of the RAS

俄罗斯联邦, Moscow

V. Kotelkin

Lomonosov Moscow State University

Email: vyacheslav.kotelkin@math.msu.ru
俄罗斯联邦, Moscow

参考

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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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