Relative depths of simple craters and the nature of the lunar regolith

Stopar, J. D.; Robinson, M. S.; Barnouin, Olivier S.; McEwen, A. S.; Speyerer, E. J.; Henriksen, M. R.; Sutton, Sarah

doi:10.1016/j.icarus.2017.05.022

Cited by 85 publications

(115 citation statements)

References 62 publications

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“…Nevertheless, considering the values for γ , when δ is allowed to vary (Tables and ), simple highland craters are deeper on average than simple mare craters (Figure a). This finding is consistent with the previous works of Pike (), Kalynn et al (), Stopar et al (), and Robbins et al ().…”

Section: Resultssupporting

confidence: 94%

“…Well‐preserved lunar simple craters show no distinct differences in their depth‐diameter ( d ‐ D ) relationship, which was also recognized by Pike (), with the general expression of d = 0.196 D 1.01 . Due to our larger, high‐resolution database, we could improve the values of γ for the simple power‐laws, but the expression of the exponent δ ≈ 1 is in good agreement with previous work (Daubar et al, ; Pike, , , , ; Stopar et al, ; Watters et al, ; Wood & Anderson, ). Separating the simple craters by terrain type reveals that simple mare craters differ from these results.…”

Section: Discussionsupporting

confidence: 89%

“…The simple power‐law fits (Table ) show similar trends to previously published literature values (Daubar et al, ; Melosh, ; Pike, , , , ; Stopar et al, ; Watters et al, ; Wood & Anderson, ), albeit our larger, high‐resolution database results in improved parameters. Our database incorporates more than 20 times the number of craters, compared with previous studies (Hale & Grieve, ; Melosh, ; Pike, , ; Pearce & Melosh, ).…”

Section: Discussionsupporting

confidence: 88%

“…Mare craters show an exponent clearly distinguishable from δ = 1, with δ = 1.1010 ± 0.0047 (diameter D ) or δ = 1.0869 ± 0.0047 (minor axis b ; Table ). Numerous previous studies show similar values for the exponent of the general power‐law form of δ ≈ 1 (Daubar et al, ; Pike, , , 1977; Stopar et al, ; Watters et al, ; Wood & Anderson, ).…”

Section: Resultssupporting

confidence: 58%

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Deriving Morphometric Parameters and the Simple‐to‐Complex Transition Diameter From a High‐Resolution, Global Database of Fresh Lunar Impact Craters (D ≥ ~ 3 km)

2018

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We compiled a high‐resolution, global lunar impact crater database composed of 5,505 pristine craters ≥ ~3 km. This database contains detailed morphometric data, and their trends are examined with best‐fit power‐laws. We compared several different functions for simple, transitional, and complex craters to report one best‐fit representation. We integrated transitional craters into these fits as an independent crater class. Transitional craters are in a transitional state, between simple and complex craters. They are devoid of a central uplift and terraces but show wall slumping and a flat floor. In regard to depth‐diameter relationships, simple craters exhibit similar scaling all over the Moon, whereas larger craters are different in highland and mare regions. In the present work, we sought the best representation of the simple‐to‐complex transition diameter. The intersection of simple power‐law fits for simple and complex crater populations is shown to be a poor representation of the transition diameter. We used a misclassification method for finding transition diameters. This process reveals a transition from simple to transitional craters at diameters of ~17 km (highland) and ~14 km (mare). Transitional morphology is replaced by complex morphology at diameters of ~ 28 km (highland) and ~ 24 km (mare). The lower transition diameters of mare craters are attributed primarily to the layered mare basalts, which enables an earlier onset of crater modification. We also analyzed the relationship between aspect ratio and depth‐diameter ratio of simple craters: Simple craters with ε ≥ 1.1 are significantly shallower in depth/diameter plots than craters with ε < 1.1.

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Section: Resultssupporting

confidence: 94%

Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 88%

Section: Resultssupporting

confidence: 58%

See 2 more Smart Citations

Deriving Morphometric Parameters and the Simple‐to‐Complex Transition Diameter From a High‐Resolution, Global Database of Fresh Lunar Impact Craters (D ≥ ~ 3 km)

2018

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“…In most cases, d r / D RIM is ~0.24, which corresponds well to the transition at D RIM / T = 4.25 (1/4.25–0.24). However, fresh and small lunar craters ( D RIM < 400 m) rarely have depth‐diameter ratios greater than 0.20 (Basilevsky et al, ; Daubar et al, ; Mahanti et al, ; Stopar et al, ). Moreover, Watters et al () suggest that the depth‐diameter ratio of secondary craters on Mars might decrease significantly with decreasing impact velocity, from U = 2 km/s (~0.22) to U = 0.2 km/s (~0.09).…”

Section: Discussionmentioning

confidence: 99%

Formation of Simple Impact Craters in Layered Targets: Implications for Lunar Crater Morphology and Regolith Thickness

et al. 2018

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Impact crater morphologies vary significantly across the lunar maria. Craters with diameter less than 400 m are closely related to variations in target properties (rock strength, porosity, and layering) as well as the impact velocity. Here we investigate target and impact conditions feasible for reproducing crater morphologies, such as normal, central‐mound, flat‐bottomed, and concentric craters, using numerical models of impact crater formation in two‐layer targets under lunar conditions (i.e., average‐impact velocity and gravity). Based on more than 1,000 numerical models, we observe that concentric craters can form with a strength contrast as low as factor of 2 between the layers as long as the difference in cohesion is larger than a value between 50 and 450 kPa (for an impact velocity of 12.7 km/s). Because of this small contrast, concentric craters do not serve as a good indication for the lunar regolith‐mare interface. Crater morphology changes with crater diameter according to three different scenarios depending on layers' strengths and the impact velocity. For high‐impact velocity or/and moderate material strength, normal crater morphology transitions directly to concentric morphology, while with large material strengths and/or low‐impact velocity, craters change with size from normal to flat‐bottomed and then to concentric morphology; only this latter pathway is consistent with previous laboratory results. Lunar regolith thicknesses estimated from crater morphologies can differ by up to 80% from previously inferred thicknesses. The transition from normal to flat‐bottomed craters is found to be the most robust transition to infer the thickness of the surficial target layer.

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Effect of Topography Degradation on Crater Size‐Frequency Distributions: Implications for Populations of Small Craters and Age Dating

Xie

Zhu

et al. 2017

Geophysical Research Letters

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Whether or not background secondary craters dominate populations of small impact craters on terrestrial bodies is a half‐century controversy. It has been suggested that small craters on some planetary bodies are dominated by background secondary craters based partly on the steepened slope of crater size‐frequency distribution (CSFD) toward small diameters, such as the less than ~1 km diameter crater population on the lunar mare. Here we show that topography degradation enlarges craters and increases CSFD slopes with time. When topography degradation is taken into account, for various‐aged crater populations, the observed steep CSFD at small diameters is uniformly consistent with an originally shallower CSFD, whose slope is undifferentiated from the CSFD slope estimated from near‐Earth objects and terrestrial bolides. The results show that the effect of topography degradation on CSFD is important in dating planetary surfaces, and the steepening of CSFD slopes is not necessarily caused by secondary cratering, but rather a natural consequence of topography degradation.

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Relative depths of simple craters and the nature of the lunar regolith

Cited by 85 publications

References 62 publications

Deriving Morphometric Parameters and the Simple‐to‐Complex Transition Diameter From a High‐Resolution, Global Database of Fresh Lunar Impact Craters (D ≥ ~ 3 km)

Deriving Morphometric Parameters and the Simple‐to‐Complex Transition Diameter From a High‐Resolution, Global Database of Fresh Lunar Impact Craters (D ≥ ~ 3 km)

Formation of Simple Impact Craters in Layered Targets: Implications for Lunar Crater Morphology and Regolith Thickness

Effect of Topography Degradation on Crater Size‐Frequency Distributions: Implications for Populations of Small Craters and Age Dating

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