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

Krüger, T.; Hergarten, Stefan; Kenkmann, T.

doi:10.1029/2018je005545

Cited by 29 publications

(42 citation statements)

References 83 publications

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“…This massive crust has been battered by impacts ever since its formation and is weaker owing to fracturing of rocks by shock waves and accumulation of impact ejecta and regolith over time. Though the highland material is less coherent than the younger mare, the homogeneity in its strength relative to the layered mare seems to be the primary factor in stabilizing the transient cavity, resulting in simple craters at larger diameters than in the mare (Krüger et al, ; Osinski et al, ).…”

Section: Discussionmentioning

confidence: 99%

Geologic Analyses of the Causes of Morphological Variations in Lunar Craters Within the Simple‐to‐Complex Transition

2019

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The diameter range of 15 to 20 km is within the transition from simple to complex impact craters located on the Moon. This range spans roughly a factor of 3 in impact energy for the same impactor speed, composition, and trajectory angle. We analyzed the global population of well‐preserved craters in this size range in order to assess the effects of target and impactor properties on crater shapes and morphologies. We observed that within this narrow diameter range, simple craters are confined to the highlands, and complex craters are more abundant in the mare. We found unusually deep craters around the highlands‐mare boundaries and favor the hypothesis that they form by impact cratering on high‐porosity terrain. We infer that target properties primarily contribute to the observed morphological variations in the craters. Simple crater formation is favored by a terrain that is more homogeneous in strength and topography, while transitional and complex crater formation is aided by heterogeneity in lithology, topography, or strength, or a combination of these parameters. Clearly visible impact melt deposits in a small percentage of simple craters, and two cases of craters differing in morphologies from their nearest neighbors in similar geologic settings, suggest that variation in impactor properties such as impact velocity and impactor size may have some role in causing morphological differences between similar‐sized craters.

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Section: Discussionmentioning

confidence: 99%

Geologic Analyses of the Causes of Morphological Variations in Lunar Craters Within the Simple‐to‐Complex Transition

2019

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“…Krüger et al. , ). Transitional craters are clearly distinguished from simple craters due to the presence of morphologic features consistent with collapse.…”

Section: Discussionmentioning

confidence: 99%

“…For a more comprehensive and detailed statistical study on a large inventory of lunar craters with D > 3 km, the reader is referred to Krüger et al. ().…”

Section: Methodsmentioning

confidence: 99%

“…The coefficients a and b, and their standard error, for logarithmic values of the X and Y values were derived by fitting a nonlinear curve via Levenberg-Marquardt iteration algorithm (Levenberg 1944;Marquardt 1963) in Origin (https://www.originlab.com). For a more comprehensive and detailed statistical study on a large inventory of lunar craters with D > 3 km, the reader is referred to Kr€ uger et al (2018).…”

Section: Methodsmentioning

confidence: 99%

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Transitional impact craters on the Moon: Insight into the effect of target lithology on the impact cratering process

Osinski

Silber

Clayton

et al. 2018

Meteorit & Planetary Scien

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We studied a data set of 28 well‐preserved lunar craters in the transitional (simple‐to‐complex) regime with the aim of investigating the underlying cause(s) for morphological differences of these craters in mare versus highland terrains. These transitional craters range from 15 to 42 km in diameter, demonstrating that the transition from simple to complex craters is not abrupt and occurs over a broad diameter range. We examined and measured the following crater attributes: depth (d), diameter (D), floor diameter (Df), rim height (h), and wall width (w), as well as the number and onset of terraces and rock slides. The number of terraces increases with increasing crater size and, in general, mare craters possess more terraces than highland craters of the same diameter. There are also clear differences in the d/D ratio of mare versus highland craters, with transitional craters in mare targets being noticeably shallower than similarly sized highland craters. We propose that layering in mare targets is a major driver for these differences. Layering provides pre‐existing planes of weakness that facilitate crater collapse, thus explaining the overall shallower depths of mare craters and the onset of crater collapse (i.e., the transition from simple to complex crater morphology) at smaller diameters as compared to highland craters. This suggests that layering and its interplay with target strength and porosity may play a more significant role than previously considered.

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“…For simple craters, the transient crater diameter is ∼0.84 times the size of the final crater diameter (Melosh, ). The largest cold‐spot crater has a diameter of 2.315 km (Williams et al, ), so all cold‐spot craters have diameters well below the simple‐to‐complex transition on the Moon (Krüger et al, ). Thus, the classic scaling laws presented in Melosh () suggest that the excavation depth is approximately 0.084 times the final crater diameter for cold‐spot craters.…”

Section: Methodsmentioning

confidence: 99%

The Subsurface Coherent Rock Content of the Moon as Revealed by Cold‐Spot Craters

et al. 2019

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A recently identified class of young lunar craters, cold‐spot craters, provides an optimal data set for probing the subsurface rock content on the Moon. Rocks, or lack of rocks, in crater ejecta have long been used as indicators of regolith thickness. However, the rockiness of crater ejecta depends on the subsurface rock content, crater excavation depth, and crater age. Cold‐spot craters are surrounded by a low thermal inertia signature that fades within 1 Myr, so any rocks in the proximal ejecta blanket have not yet been broken down or buried. Thus, the rock abundance in the proximal ejecta blankets of cold‐spot craters is affected only by the subsurface rock content of the target and the crater excavation depth, not the age of the crater. We show that an abrupt transition between fine‐grained regolith and underlying coherent rock cannot explain the observed rock abundance. Instead, we assume that the volume fraction of coherent rock (in contrast to fine‐grained regolith) increases exponentially in the lunar subsurface and use the observed Diviner rock abundance in cold‐spot crater ejecta to solve for the “e‐folding” depth over which the volume fraction of rock increases. In general, the subsurface rock content is higher in the maria than in the highlands consistent with more recent resurfacing of the maria. However, the highlands show a wider range of subsurface rock content values overall including some overlapping those of the maria. Some of this variability appears to be associated with the Orientale basin and possibly with several cryptomare deposits.

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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)

Cited by 29 publications

References 83 publications

Geologic Analyses of the Causes of Morphological Variations in Lunar Craters Within the Simple‐to‐Complex Transition

Geologic Analyses of the Causes of Morphological Variations in Lunar Craters Within the Simple‐to‐Complex Transition

Transitional impact craters on the Moon: Insight into the effect of target lithology on the impact cratering process

The Subsurface Coherent Rock Content of the Moon as Revealed by Cold‐Spot Craters

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