Mercury's Northern Rise Core‐Field Magnetic Anomaly

Plattner, Alain; Johnson, C. L.

doi:10.1029/2021gl094695

Cited by 9 publications

(4 citation statements)

References 56 publications

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“…This means that the mantle plug loading at the Caloris region dominates the overall loading of the lithosphere in the region. This illustrates the difference between the compensation mechanisms in the Caloris basin (CrMB isostatic compensation) and the Northern rise regions (deep mantle compensation demonstrated by high admittance, also suggested in Plattner and Johnson (2021)). Nevertheless, the recent estimation of load depth under the Northern Rise region is about 29 ± 13 km (area 4 in Goossens et al (2022b)), which represents a shallow loading scenario.…”

Section: Lithospheric Elastic Thickness and Load State Of The Caloris...mentioning

confidence: 69%

Lithospheric Elastic Thickness Beneath the Caloris Basin: Implications for the Thermal Structure of Mercury

Deng

Zhong

et al. 2023

JGR Planets

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The basin interior is covered by the Caloris interior plains (CIP) that have been deformed by complex tectonic features (Denevi et al., 2018), including concentric ridges and tensional grabens that exhibit both radial and tangential strikes (Byrne et al., 2018). Both the northern and southern parts of the basin floor have been significantly uplifted to heights that exceed the basin rim (Figure 1c), and the two mountain belts have a trend that is more-or-less parallel to the east-northeast to west-southwest direction (Byrne et al., 2014).

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Section: Lithospheric Elastic Thickness and Load State Of The Caloris...mentioning

confidence: 69%

Lithospheric Elastic Thickness Beneath the Caloris Basin: Implications for the Thermal Structure of Mercury

Deng

Zhong

et al. 2023

JGR Planets

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“…If such an internal magnetic field structure with an m = 2 character and 88 day periodicity could be inferred from observations of Mercury's magnetic field, and recent papers (e.g., Plattner & Johnson 2021;Wardinski et al 2021) show that this might indeed be possible, then the strength of that magnetic field could inform on the Brunt-Väisälä frequency near the CMB, as well as the Ekman number in the outer core and the triaxial shape of the CMB. But, as the induced magnetic field results are based on a model assuming laminar flow, and we expect the flow near the CMB to be turbulent, further study is needed to take nonlinear interactions within the fluid into account and draw any definitive conclusions.…”

Section: Discussionmentioning

confidence: 99%

“…Recent reconstructions of Mercury's magnetic field, inferred from MESSENGER magnetic field observations, show that nonaxisymmetric magnetic field components might contribute from 3% (Plattner & Johnson 2021) to 20% (Wardinski et al 2021) to the rms signal of the radial magnetic field at the core surface. The estimated Y 2 2 components of Mercury's stationary internal magnetic field (i.e., the g 2 2 and h 2 2 Gauss coefficients) are around 1 nT (Wardinski et al 2019), similar to the librationally induced periodic magnetic field we compute above for N 0 = 100, Ek = 2 × 10 −13 , and α 2 = 10 −4 , although its value is uncertain due to MESSENGER's orbital geometry (Anderson et al 2012;Thébault et al 2018;Toepfer et al 2022).…”

Section: Stratification Induces a Nonaxisymmetric Magnetic Field Stru...mentioning

confidence: 99%

Effects of the Librationally Induced Flow in Mercury’s Fluid Core with an Outer Stably Stratified Layer

Seuren,

Triana,

Rekier

et al. 2023

Planet. Sci. J.

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Observational constraints on Mercury’s thermal evolution and magnetic field indicate that the top part of the fluid core is stably stratified. Here we compute how a stable layer affects the core flow in response to Mercury’s main 88 day longitudinal libration, assuming various degrees of stratification, and study whether the core flow can modify the libration amplitude through viscous and electromagnetic torques acting on the core–mantle boundary (CMB). We show that the core flow strongly depends on the strength of the stratification near the CMB but that the influence of core motions on libration is negligible with or without a stably stratified layer. A stably stratified layer at the top of the core can, however, prevent resonant behavior with gravito-inertial modes by impeding radial motions and promote a strong horizontal flow near the CMB. The librationally driven flow is likely turbulent and might produce a nonaxisymmetric induced magnetic field with a strength of the order of 1% of Mercury’s dipolar field.

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“…Another possibility raised by James (2018) is that the cause of the northern rise lies deeper in Mercury, in the mantle or at the base of the crust. Recent analysis of magnetic data also hints at this (Plattner & Johnson 2021). In order to probe this, we reanalyzed the admittance curve for area 4, this time ensuring that the model has the load depth in the mantle (z > T c ), which also means a negative load parameter (Grott & Wieczorek 2012).…”

Section: Northern Risementioning

confidence: 97%

Estimation of Crust and Lithospheric Properties for Mercury from High-resolution Gravity and Topography

Goossens¹,

Genova²,

James³

et al. 2022

Planet. Sci. J.

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We have analyzed the entire set of radiometric tracking data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. This analysis employed a method where standard Doppler tracking data were transformed into line-of-sight accelerations. These accelerations have greater sensitivity to small-scale features than standard Doppler. We estimated a gravity model expressed in spherical harmonics to degree and order 180 and showed that this model is improved, as it has increased correlations with topography in areas where tracking data were collected when the spacecraft altitude was low. The new model was used in an analysis of the localized admittance between gravity and topography to determine properties of Mercury’s lithosphere. Four areas with high correlations between gravity and topography were selected. These areas represent different terrain types: the high-Mg region, the Strindberg crater plus some lobate scarps, heavily cratered terrain, and smooth plains. We employed a Markov Chain Monte Carlo method to estimate crustal density, load density, crustal thickness, elastic thickness, load depth, and a load parameter that describes the ratio between surface and depth loading. We find densities around 2600 kg m−3 for three of the areas, with the density for the fourth area, the northern rise, being higher. The elastic thickness is generally low, between 11 and 30 km.

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Mercury's Northern Rise Core‐Field Magnetic Anomaly

Cited by 9 publications

References 56 publications

Lithospheric Elastic Thickness Beneath the Caloris Basin: Implications for the Thermal Structure of Mercury

Lithospheric Elastic Thickness Beneath the Caloris Basin: Implications for the Thermal Structure of Mercury

Effects of the Librationally Induced Flow in Mercury’s Fluid Core with an Outer Stably Stratified Layer

Estimation of Crust and Lithospheric Properties for Mercury from High-resolution Gravity and Topography

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