Examining the power supplied to Earth's dynamo by magnesium precipitation and radiogenic heat production

IF 2.4 3区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS
Alfred J. Wilson , Monica Pozzo , Christopher J. Davies , Andrew M. Walker , Dario Alfè
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引用次数: 0

Abstract

We examine magnesium and potassium solubility in liquid Fe mixtures, representative of Earth's core composition, in equilibrium with liquid silicate mixtures representative of an early magma ocean. Our study is based on the calculation of the chemical potentials of MgO and K2O in both phases, using density functional theory. For MgO, we also study stability against precipitation of the solid phase. We use thermal evolution models of the core and mantle to assess whether either radiogenic heating from 40K decay or Mg precipitation from the liquid core can resolve the new core paradox by powering the geodynamo prior to inner core formation. Our results for K show that concentrations in the core are likely to be small and the effect of 40K decay on the thermal evolution of the core is minimal, making it incapable of sustaining the early geodynamo alone. Our results also predict small concentrations of Mg in the core which might be sufficient to power the geodynamo prior to inner core formation, depending on the process by which it is transported across the core mantle boundary.

检查通过镁沉淀和放射热产生提供给地球发电机的电力
我们研究了镁和钾在液态铁混合物中的溶解度,这代表了地球的核心成分,与代表早期岩浆海洋的液态硅酸盐混合物平衡。我们的研究是基于密度泛函理论计算两相中MgO和K2O的化学势。对于氧化镁,我们还研究了固相沉淀的稳定性。我们使用地核和地幔的热演化模型来评估来自40K衰变的放射性成因加热或来自液态地核的Mg沉淀是否可以通过在内核形成之前为地球发电机提供动力来解决新的核心悖论。我们的结果表明,K在岩心中的浓度可能很小,40K衰变对岩心热演化的影响很小,使其无法单独维持早期的地球动力学。我们的研究结果还预测,在内核形成之前,核中少量的Mg浓度可能足以为地球发电机提供动力,这取决于它通过核幔边界运输的过程。
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来源期刊
Physics of the Earth and Planetary Interiors
Physics of the Earth and Planetary Interiors 地学天文-地球化学与地球物理
CiteScore
5.00
自引率
4.30%
发文量
78
审稿时长
18.5 weeks
期刊介绍: Launched in 1968 to fill the need for an international journal in the field of planetary physics, geodesy and geophysics, Physics of the Earth and Planetary Interiors has now grown to become important reading matter for all geophysicists. It is the only journal to be entirely devoted to the physical and chemical processes of planetary interiors. Original research papers, review articles, short communications and book reviews are all published on a regular basis; and from time to time special issues of the journal are devoted to the publication of the proceedings of symposia and congresses which the editors feel will be of particular interest to the reader.
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