Evidence of mantle upwelling/downwelling and localized subduction on Venus from the body-force vector analysis

Zampa, Luigi; Tenzer, Róbert; Eshagh, Mehdi; Pitoňák, Martin

doi:10.1016/j.pss.2018.03.013

Cited by 9 publications

(8 citation statements)

References 44 publications

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“…In addition to these elastic effects, the lithosphere can deform plastically in response to convective stress, as illustrated by the crustal thickening example in Figure 1(b) (Kiefer & Hager 1991;Pysklywec & Shahnas 2003;Zampa et al 2018). We have not considered higher-order effects from the formation of a crust, whose marginally lower density with respect to mantle rock would buoy topography slightly higher.…”

Section: Filtering In the Lithospherementioning

confidence: 99%

“…Note that stagnant lid convection can lead to other forms of topography, beyond just that supported dynamically by convection (Figure 1). The melting associated with hot upwelling mantle can form thick, low-density crust as in Figure 1(d) (Stofan et al 1995); further, tension above downwelling plumes can also thicken the crust tectonically as in Figure 1(b) (Kiefer & Hager 1991;Pysklywec & Shahnas 2003;Zampa et al 2018). Both phenomena would induce compositional isostasy, resulting in altitudes unrepresentative of pure dynamic support.…”

Section: Introductionmentioning

confidence: 99%

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Blue Marble, Stagnant Lid: Could Dynamic Topography Avert a Waterworld?

2022

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Topography on a wet rocky exoplanet could raise land above its sea level. Although land elevation is the product of many complex processes, the large-scale topographic features on any geodynamically active planet are the expression of the convecting mantle beneath the surface. This so-called “dynamic topography” exists regardless of a planet’s tectonic regime or volcanism; its amplitude, with a few assumptions, can be estimated via numerical simulations of convection as a function of the mantle Rayleigh number. We develop new scaling relationships for dynamic topography on stagnant lid planets using 2D convection models with temperature-dependent viscosity. These scalings are applied to 1D thermal history models to explore how dynamic topography varies with exoplanetary observables over a wide parameter space. Dynamic topography amplitudes are converted to an ocean basin capacity, the minimum water volume required to flood the entire surface. Basin capacity increases less steeply with planet mass than does the amount of water itself, assuming a water inventory that is a constant planetary mass fraction. We find that dynamically supported topography alone could be sufficient to maintain subaerial land on Earth-size stagnant lid planets with surface water inventories of up to approximately 10−4 times their mass, in the most favorable thermal states. By considering only dynamic topography, which has ∼1 km amplitudes on Earth, these results represent a lower limit to the true ocean basin capacity. Our work indicates that deterministic geophysical modeling could inform the variability of land propensity on low-mass planets.

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Section: Filtering In the Lithospherementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Blue Marble, Stagnant Lid: Could Dynamic Topography Avert a Waterworld?

2022

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“…Эти результаты согласуются с выводами [Hansen, Banks, Ghent, 1999;Ivanov, Head, 2011;, где отмечено, что если сравнить области с толстой корой, рассчитанные в предположении изостазии, с распределением высокогорных плато и тессер, то можно увидеть корреляцию. Максимальная глубина Мохо, превышающая 90 км, получена под горами Максвелла и Землей Иштар, что согласуется с результатами работы [Zampa et al, 2018].…”

Section: результатыunclassified

“…Толщина коры на Венере тесно связана с топографическими структурами: тонкая кора определяется под равнинами, толстая -под поднятиями. Максимальная глубина залегания границы Мохо, превышающая 90 км, получена под горами Максвелла и Землей Иштар [Zampa et al, 2018].…”

unclassified

Load Love numbers for various rheological models of Venus

2021

Геофиз.Исслед.

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Рассчитаны нагрузочные числа Лява для различных моделей неоднородной упругости Венеры, используя статический подход для нагрузки на поверхности (рельеф планеты) и для заглубленных аномальных волн плотности. Планета моделировалась как упругое самогравитирующее тело с зависящими от радиуса плотностью, модулем сжатия и модулем сдвига. Вычисления проводились для каждой гармоники до степени и порядка n=70, исходя из точности определения гравитационного поля на данный момент.В статье рассматрено три модели неоднородной упругости Венеры. Первой анализировалась чисто упругая модель (модель А). Вторая модель (модель В) предполагала наличие упругой литосферы, под которой был введен простирающийся до ядра ослабленный слой, частично потерявший свои упругие свойства. Ослабление в этом слое моделировалось пониженным в десять раз значением модуля сдвига. Толщина упругого литосферного слоя варьировалась от 100 до 500 км. В третьей модели (модели С) в ослабленном слое под корой задавалось градиентное изменение модуля сдвига -пониженное в десять раз значение модуля сдвига непосредственно под корой постепенно увеличивалось до его значения в упругой модели на границе с ядром. На основе описанных моделей проведена интерпретация аномального внешнего гравитационного поля. Показано, что нагрузочные числа чувствительны к реологическому строению планеты и это может быть использовано при выборе между моделями неоднородной упругости Венеры. Построена карта рельефа границы корамантия, рассчитанная в предположении изостатической компенсации. Полученные значения толщины коры могут быть несколько меньше реальных, так как в работе не учтена компонента динамической компенсации.

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“…Note that stagnant lid convection can lead to other forms of topography, beyond just that supported dynamically by convection (figure 1). The melting associated with hot upwelling mantle can form thick, lowdensity crust as in figure 1d (Stofan et al 1995); further, tension above downwelling plumes can also thicken the crust tectonically as in figure 1b (Kiefer & Hager 1991;Pysklywec & Shahnas 2003;Zampa et al 2018). Both phenomena would induce compositional isostasy, resulting in altitudes unrepresentative of pure dynamic support.…”

Section: Introductionmentioning

confidence: 99%

Blue marble, stagnant lid: Could dynamic topography avert a waterworld?

Guimond,

Rudge,

Shorttle

2022

Preprint

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Topography on a wet rocky exoplanet could raise land above its sea level. Although land elevation is the product of many complex processes, the large-scale topographic features on any geodynamicallyactive planet are the expression of the convecting mantle beneath the surface. This so-called "dynamic topography" exists regardless of a planet's tectonic regime or volcanism; its amplitude, with a few assumptions, can be estimated via numerical simulations of convection as a function of the mantle Rayleigh number. We develop new scaling relationships for dynamic topography on stagnant lid planets using 2D convection models with temperature-dependent viscosity. These scalings are applied to 1D thermal history models to explore how dynamic topography varies with exoplanetary observables over a wide parameter space. Dynamic topography amplitudes are converted to an ocean basin capacity, the minimum water volume required to flood the entire surface. Basin capacity increases less steeply with planet mass than does the amount of water itself, assuming a water inventory that is a constant planetary mass fraction. We find that dynamically-supported topography alone could be sufficient to maintain subaerial land on Earth-size stagnant lid planets with surface water inventories of up to approximately 10 −4 times their mass, in the most favourable thermal states. By considering only dynamic topography, which has ∼1-km amplitudes on Earth, these results represent a lower limit to the true ocean basin capacity. Our work indicates that deterministic geophysical modelling could inform the variability of land propensity on low-mass planets.

show abstract

Evidence of mantle upwelling/downwelling and localized subduction on Venus from the body-force vector analysis

Cited by 9 publications

References 44 publications

Blue Marble, Stagnant Lid: Could Dynamic Topography Avert a Waterworld?

Blue Marble, Stagnant Lid: Could Dynamic Topography Avert a Waterworld?

Load Love numbers for various rheological models of Venus

Blue marble, stagnant lid: Could dynamic topography avert a waterworld?

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