Journal: Journal of Geophysical Research: Planets

Abbreviation

J. geophys. res. Planets.

Publisher

American Geophysical Union

Journal Volumes

ISSN

0148-0227
2169-9097
2169-9100

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Publications 1 - 10 of 62
  • Gravity and Magnetic Field Signatures in Hydrothermally Affected Regions on Mars
    Item type: Journal Article
    Mittelholz, Anna; Moorkamp, Max; Broquet, Adrien; et al. (2025)
    Journal of Geophysical Research: Planets
    Multiple lines of evidence indicate that liquid water-rock interactions occurred on ancient Mars, particularly within the crust, where hydrothermal systems have been hypothesized. Such hydrothermal circulation (HC) can significantly lower temperatures in the crust, thereby restricting the viscoelastic relaxation of impact craters. Craters with minimal relaxation are characterized by their large depth-to-diameter ratio and prominent Bouguer gravity anomalies. Additionally, HC can induce magnetic anomalies through chemical remanent magnetization (CRM). Consequently, if HC was widespread on Mars, the gravitational signatures of unrelaxed craters may correlate with their magnetic signatures. To investigate how HC influenced the magnetic characteristics of the Martian crust, we focus on the region surrounding several unrelaxed craters in the southern highlands, where hydrothermal activity was likely prevalent. We use a newly developed joint inversion approach and model magnetization and density in such regions to investigate how hydrothermal systems affect those parameters. The inversion approach makes use of a mutual information term in which models with a parameter relationship are favored, that is, models in which magnetization and density distributions are correlated. Despite showing large Bouguer gravity anomalies and forming over 3.75 billion years ago, when the Martian dynamo was most likely active, investigated craters and surrounding regions exhibit minimal magnetic anomalies. We propose that this lack of magnetic signatures is most likely due to demagnetization of the crust through CRM, induced by HC long after the Martian dynamo ceased. Our findings suggest that deep, long-lived hydrothermal systems-likely fueled by heat-producing elements-were present, potentially creating habitable conditions on early Mars.
  • Using Boulder Tracks as a Tool to Understand the Bearing Capacity of Permanently Shadowed Regions of the Moon
    Item type: Journal Article
    Sargeant, Hannah M.; Bickel, Valentin; Honniball, Casey I.; et al. (2020)
    Journal of Geophysical Research: Planets
    Permanently shadowed regions (PSRs) are abundant at the lunar poles. They experience no direct sunlight and reach temperatures as low as 30 K. PSRs are of interest as evidence suggests that some may contain water ice (H2O/OH‐), which could provide a record of the evolution of volatiles in the inner solar system. This water ice is also a critical resource for life‐support systems and rocket propellant. A better understanding of mechanical properties of PSR regolith, such as its bearing capacity, will help optimize the design of future exploration rovers and landers. Thirteen boulder tracks were identified on the edge of, or inside, south polar lunar PSR enhanced imagery and used to estimate the strength of the PSR regolith at latitudes of 70° to 76° in sites with maximum annual temperatures of 65 to 210 K. PSR boulder track features are similar to those observed in highland, mare, and pyroclastic regions of the Moon, implying similar properties of the regolith. Measured features were used to estimate bearing capacity for PSR regolith at depths of ~0.28 to 4.68 m. Estimated bearing capacity values suggest that these PSRs may be somewhat stronger than highland and mare regions at depths of 0.28 to 1.00 m. Bearing capacity in these PSRs is statistically the same as those in other regions of the Moon at depths of 1.00 to 2.00 m. The results of this study can be used to infer bearing capacity as one measure for the trafficability of lower‐latitude PSRs of the type measured here.
  • On‐Deck Seismology: Lessons from InSight for Future Planetary Seismology
    Item type: Journal Article
    Panning, Mark P.; Pike, W.T.; Lognonne, Philippe; et al. (2020)
    Journal of Geophysical Research: Planets
  • The Effect of Pressure-Dependent Viscosity on the Dynamics of the Post-Overturn Lunar Mantle
    Item type: Journal Article
    Zhang, Wenbo; Zhang, Nan; Liang, Yan; et al. (2023)
    Journal of Geophysical Research: Planets
    Mare-basalt volcanism is concentrated on the lunar nearside. A plausible explanation for this asymmetric distribution is long-wavelength (spherical harmonic degree-1) mantle convection driven by upwellings of the overturned ilmenite-bearing magma ocean cumulates (IBCs). The pattern of lunar mantle convection depends in part on the rheological properties of ilmenite. This study explores the effect of pressure-dependent ilmenite viscosity on the instability of an overturned IBC layer initially at the core-mantle boundary and the pattern of lunar mantle convection through three-dimensional numerical simulations. We show that the convective patterns are sensitive to the activation volume for viscous flow. An effective activation volume of 10 cm3/mol would reduce the internal convection in the overturned IBC layer and promote the hemispherical upwelling. However, when the activation volume is too small, vigorous convection in the overturned IBC layer would inhibit heat from concentrating on one hemisphere. When the activation volume is too large, the size of the upwelling plumes is restricted, preventing a stable long-wavelength structure in the upper mantle. Decompression melting during asymmetric upwelling would produce the localization of mare basalts on the lunar surface.
  • Natural Orthogonal Component Analysis of Daily Magnetic Variations at the Martian Surface: InSight Observations
    Item type: Journal Article
    Hao, Luo; Du, Aimin; Ge, Yasong; et al. (2022)
    Journal of Geophysical Research: Planets
    Distinguishing different sources of magnetic field variations at InSight is important to understand dynamic processes in the Martian ionosphere as well as the coupling between the solar wind and the Martian induced magnetosphere. Recent studies based on magnetic field measurements from InSight have suggested that the daily and seasonal variations in the magnetic field at the Martian surface are at least partially the result of neutral wind-driven ionospheric dynamo currents and their seasonal variations. However, the sources of the daily variations with different time scales need be further investigated. In this paper, magnetic field variations in a sol as well as during nearly a whole Martian year from InSight observations were decomposed into their natural orthogonal components. We found that the first eigenmode shows the previously identified early to midmorning peak, and varies with season. This corresponds to the solar quiet variations. The second and higher eigenmodes manifest the quasi-Carrington and sub-Carrington rotation periodicity represent disturbed components that may be stimulated by variations in the draped interplanetary magnetic field and/or the Martian ionospheric electron density. Different from their counterparts at the Earth, the amplitude of the first eigenmode is comparable with the sum of second to fifth ones, showing that the quiet and disturbed diurnal variations contribute similarly to the total diurnal variation. Decomposition of Martian surface magnetic field variations could provide monitoring of the Martian ionospheric current system as well as the solar wind conditions in the near-Mars space, which will be greatly enhanced when combined with Zhurong Martian surface field measurements in the future.
  • Vertically Resolved Magma Ocean–Protoatmosphere Evolution: H2, H2O, CO2, CH4, CO, O2, and N2 as Primary Absorbers
    Item type: Journal Article
    Lichtenberg, Tim; Bower, Dan J.; Hammond, Mark; et al. (2021)
    Journal of Geophysical Research: Planets
    The earliest atmospheres of rocky planets originate from extensive volatile release during magma ocean epochs that occur during assembly of the planet. These establish the initial distribution of the major volatile elements between different chemical reservoirs that subsequently evolve via geological cycles. Current theoretical techniques are limited in exploring the anticipated range of compositional and thermal scenarios of early planetary evolution, even though these are of prime importance to aid astronomical inferences on the environmental context and geological history of extrasolar planets. Here, we present a coupled numerical framework that links an evolutionary, vertically resolved model of the planetary silicate mantle with a radiative‐convective model of the atmosphere. Using this method, we investigate the early evolution of idealized Earth‐sized rocky planets with end‐member, clear‐sky atmospheres dominated by either H2, H2O, CO2, CH4, CO, O2, or N2. We find central metrics of early planetary evolution, such as energy gradient, sequence of mantle solidification, surface pressure, or vertical stratification of the atmosphere, to be intimately controlled by the dominant volatile and outgassing history of the planet. Thermal sequences fall into three general classes with increasing cooling timescale: CO, N2, and O2 with minimal effect, H2O, CO2, and CH4 with intermediate influence, and H2 with several orders of magnitude increase in solidification time and atmosphere vertical stratification. Our numerical experiments exemplify the capabilities of the presented modeling framework and link the interior and atmospheric evolution of rocky exoplanets with multiwavelength astronomical observations.
  • Magma Ocean Evolution at Arbitrary Redox State
    Item type: Journal Article
    Nicholls, Harrison; Lichtenberg, Tim; Bower, Dan J.; et al. (2024)
    Journal of Geophysical Research: Planets
    Interactions between magma oceans and overlying atmospheres on young rocky planets leads to an evolving feedback of outgassing, greenhouse forcing, and mantle melt fraction. Previous studies have predominantly focused on the solidification of oxidized Earth-similar planets, but the diversity in mean density and irradiation observed in the low-mass exoplanet census motivate exploration of strongly varying geochemical scenarios. We aim to explore how variable redox properties alter the duration of magma ocean solidification, the equilibrium thermodynamic state, melt fraction of the mantle, and atmospheric composition. We develop a 1D coupled interior-atmosphere model that can simulate the time-evolution of lava planets. This is applied across a grid of fixed redox states, orbital separations, hydrogen endowments, and C/H ratios around a Sun-like star. The composition of these atmospheres is highly variable before and during solidification. The evolutionary path of an Earth-like planet at 1 AU ranges between permanent magma ocean states and solidification within 1 Myr. Recently solidified planets typically host (Formula presented.) - or (Formula presented.) -dominated atmospheres in the absence of escape. Orbital separation is the primary factor determining magma ocean evolution, followed by the total hydrogen endowment, mantle oxygen fugacity, and finally the planet's C/H ratio. Collisional absorption by (Formula presented.) induces a greenhouse effect which can prevent or stall magma ocean solidification. Through this effect, as well as the outgassing of other volatiles, geochemical properties exert significant control over the fate of magma oceans on rocky planets.
  • Equation of State of SiC at Extreme Conditions: New Insight Into the Interior of Carbon-Rich Exoplanets
    Item type: Journal Article
    Miozzi, Francesca; Morard, Guillaume; Antonangeli, Daniele; et al. (2018)
    Journal of Geophysical Research: Planets
  • Regional-Scale Lithospheric Recycling on Venus Via Peel-Back Delamination
    Item type: Journal Article
    Adams, Andrea C.; Stegman, Dave R.; Smrekar, Suzanne E.; et al. (2022)
    Journal of Geophysical Research: Planets
    We currently have a limited understanding of the tectonic framework that governs Venus. Schubert and Sandwell (1995, https://doi.org/10.1006/icar.1995.1150) identified over 10,000 km of possible subduction sites at both coronae and chasmata rift zones. Previous numerical and experimental studies have shown the viability of regional-scale lithospheric recycling via plume-lithosphere interactions at coronae, yet little work has been done to study the possibility of resurfacing initiated at Venusian rift zones. We created 2D numerical models to test if and how regional-scale resurfacing could be initiated at a lateral lithospheric discontinuity. We observed several instances of peel-back delamination—a form of lithospheric recycling in which the dense lithospheric mantle decouples and peels away from the weak, initially 30 km-thick crust, leaving behind a hot, thinned layer of crust at the surface. Delamination initiation is driven by the negative buoyancy of the lithospheric mantle and is resisted by the coupling of the plate across the Moho, the significant positive buoyancy of the crust arising from a range of crustal densities, and the viscous strength of the plate. Initial plate bending promotes yielding and weakening in the crust, which is crucial to allow decoupling of the crust and lithospheric mantle. When there is sufficient excess negative buoyancy in the lithospheric mantle, both positively and negatively buoyant plates may undergo delamination. Following a delamination event, the emplacement of hot, buoyant asthenosphere beneath the crust may have consequences for regional-scale volcanism and local tectonic deformation on Venus within the context of the regional equilibrium resurfacing hypothesis.
  • Experimental Crystallization of the Lunar Magma Ocean, Initial Selenotherm and Density Stratification, and Implications for Crust Formation, Overturn and the Bulk Silicate Moon Composition
    Item type: Journal Article
    Schmidt, Max W.; Kraettli, Giuliano (2022)
    Journal of Geophysical Research: Planets
    Eleven isobaric experimental series simulate the fractional crystallization of 1,150 km deep lunar magma ocean. Crystallization begins at 1,850°C with olivine (to 32 per cent solidified, pcs), followed at 1,600°C by olivine + opx ± Cr-spinel (to 62 pcs), at 1,210°C cpx + plagioclase ± olivine ± Ti-spinel (to 97 pcs) and at 1,060°C quartz + cpx + plagioclase + Ti-spinel, leaving 1.8 wt% residual magma that crystallizes minor K-feldspar and apatite in addition. Melt compositions remain near 45 wt% SiO2, while FeO increases from 11 to 26 wt%, TiO2 peaks at 4 wt% at Ti-spinel saturation. The available experimental liquid lines of descent yield an overall fractional crystallization sequence of olivine→opx→cpx + plagioclase→quartz→FeTi-oxide. Plagioclase appears concomitantly with cpx, a result of the low magma ocean floor pressures (≤1 GPa) after 66%–76% of olivine + opx-fractionation. A few wt% of FeTi-oxides form mostly once the quartz + plagioclase + cpx-cotectic is reached, cumulate densities remain ≤3,740 kg/m3. Scaled to a full magma ocean, plagioclase appears at 210–120 km depth, mainly as a function of bulk Al2O3. As buoyancy driven plagioclase-cpx separation is likely limited, these depths may correspond to the primordial lunar crustal thickness. Allowing for complete plagioclase flotation to the quartz + plagioclase + cpx + FeTi-oxide ± olivine cotectic yields 95–70 km primordial crust of anorthosite and quartz-gabbro, far in excess of the 35–50 km observed. This supports an overturn of primordial layers, remelting of dense gabbroic cumulates in the harzburgitic cumulate mantle leading to further mixing and differentiation. We posit that such complex density induced convection led to a lunar marble cake mantle with primitive and fairly evolved reprocessed cumulates next to each other.
Publications 1 - 10 of 62