3D-simulation of lunar megaregolith evolution: Quantitative constraints on spatial variation and size of fragment

Liu, Tiantian; Wünnemann, K.; Michael, Greg

doi:10.1016/j.epsl.2022.117817

Cited by 4 publications

(3 citation statements)

References 46 publications

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“…In addition, this early bombardment likely engendered an early Mercury megaregolith analogous to the lunar counterpart (Liu et al 2022). Consequently, we propose a novel potential atmospheric source-the sudden degasification of this primordial megaregolith.…”

Section: Deciphering the Genesis And Evolution Of Mercury'smentioning

confidence: 79%

Mercury’s Hidden Past: Revealing a Volatile-dominated Layer through Glacier-like Features and Chaotic Terrains

Rodriguez,

Domingue,

Travis

et al. 2023

Planet. Sci. J.

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The discovery of global elemental volatile compositions, sublimation hollows, and chaotic terrains has significantly reshaped our understanding of Mercury’s geology. These findings suggest the existence of volatile-rich layers (VRLs) extending several kilometers in depth, challenging the traditionally held view of a predominantly volatile-devoid Mercury crust. However, the precise nature and origin of these VRLs remain to be elucidated. The Raditladi basin exhibits morphologies analogous to terrestrial and Martian glaciers. These geomorphological features are potentially derived from impact-exposed VRLs, likely constituted of halite, other semivolatile salts, or organic volatiles. The distinctive rheological traits of substances such as halite substantiate this hypothesis. The inference posits a potential ubiquity of VRLs on a planetary scale, albeit potentially ensconced at considerable depth in specific regions. North polar chaotic terrains elucidate the VRLs’ genesis and temporal evolution. The intense fragmentation of heavily cratered landscapes during their formation indicates a composition dominated by volatiles. This finding postulates a phase of volatile-enriched crustal accretion predating the Late Heavy Bombardment (∼3.9 Ga). Regardless of lost mass, the unaltered basal elevation post-collapse signals a transition to a volatile-free stratum. The exposure of an exhumed lithological substrate within Mercury’s stratigraphy, identifiable in gravimetry as an impacted paleosurface, contests the magma ocean differentiation concept for VRL formation. It infers a grand-scale construct originating from depositional processes, possibly due to the collapse of a transient, hot primordial atmosphere.

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Section: Deciphering the Genesis And Evolution Of Mercury'smentioning

confidence: 79%

Mercury’s Hidden Past: Revealing a Volatile-dominated Layer through Glacier-like Features and Chaotic Terrains

Rodriguez,

Domingue,

Travis

et al. 2023

Planet. Sci. J.

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“…Our impact mixing model, which allows for tracing the evolution of material age distribution with long-term bombardment, has been applied to different components such as impact melt, mare/highland materials, and different-sized fragments (Liu et al 2020a(Liu et al , 2020b(Liu et al , 2022b. In this study, we focus on the impact melt but take different scenarios of the early bombardment rate into account.…”

Section: Methodsmentioning

confidence: 99%

The Timeline of Early Lunar Bombardment Constrained by the Evolving Distributions of Differently Aged Melt

Liu,

Michael,

Wünnemann

2023

Planet. Sci. J.

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The timeline of the early lunar bombardment remains unclear. The bombardment rate as a function of time is commonly modeled by three types of shapes: tail-end, sawtooth, and terminal cataclysm. Differently aged melt records the occurrence time of impact events and thus is crucial for constraining the timeline of the early lunar bombardment. Based on a spatially resolved numerical model, we simulate the evolving distribution of differently aged melt with a long-term impact mixing, where different shapes of impact rate function are considered. We compare the outcome of melt age distribution from different scenarios with the actual data from the lunar meteorites and the returned samples. The results suggest that, if the present data are representative of the melt age distribution on the Moon, the shape of the impact rate function is more likely comparable to the tail-end over the sawtooth and the terminal cataclysm, with the terminal cataclysm being least likely. In addition, using state-of-the-art U–Pb dating techniques, more abundant ancient basin melt is likely to be found in returned samples.

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“…The bulk density and strength for the lower intact bedrock are selected as: ρ l = 3,200 kg/m 3 (Kiefer et al, 2012) and Y l = 20 Mpa (Asphaug et al, 1996), respectively. The thickness of the fractured bedrock layer at the end of our 3.5 Gyr simulations is determined by scaling the upper megaregolith thickness of 2.5 km inferred to have formed primarily from 4.31 to 3.8 Ga by Liu et al (2022). This gives fractured bedrock thicknesses of 246 and 192 m for the nonconstant and constant impact flux models respectively (see Text S4 in Supporting Information S1 for detail).…”

Section: Parameter Settingsmentioning

confidence: 99%

Modeling the Evolution of Lunar Regolith: 2. Growth Rate and Spatial Distribution

Zhang,

Fa,

Barnard

et al. 2023

JGR Planets

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The evolution of regolith thickness induced by continuous impact events on the lunar surface provides valuable information about lunar geology and the bombardment history of the inner Solar System. In this study, we develop a Lunar Topography and Regolith Evolution Model based on the production and distribution of lunar regolith resulting from individual impact craters. Considering the changing impact flux, evolving target properties, topographic degradation process, and crater superposition, our model simultaneously simulates both the spatial and temporal evolution of lunar cratered topography and regolith thickness. The modeled regolith thickness generally aligns with results estimated by in situ seismic experiments and measurements of small crater morphology. Through our simulations, we establish a novel quantitative relation between regolith growth rate and time, providing new constraints on the impact flux trend and buffering trend in the regolith growth process. By comparing this new relation with that predicted by our analytical regolith evolution model, we reveal the significant influences of evolving target properties and regolith distribution on the regolith growth rate. Our modeled results also show that the regional regolith thickness follows a characteristic long‐tailed distribution with substantial lateral variations. Both the root‐mean‐square fluctuation and correlation length of lunar regolith increase with lateral scale and the surface age, which are ∼4.7 and 18 m on the hectometer scale at 3.5 Ga. All these results contribute to a better understanding of the regolith evolution process and can provide valuable insights into the lunar surface dynamics.

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3D-simulation of lunar megaregolith evolution: Quantitative constraints on spatial variation and size of fragment

Cited by 4 publications

References 46 publications

Mercury’s Hidden Past: Revealing a Volatile-dominated Layer through Glacier-like Features and Chaotic Terrains

Mercury’s Hidden Past: Revealing a Volatile-dominated Layer through Glacier-like Features and Chaotic Terrains

The Timeline of Early Lunar Bombardment Constrained by the Evolving Distributions of Differently Aged Melt

Modeling the Evolution of Lunar Regolith: 2. Growth Rate and Spatial Distribution

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