Ejecta Blanket Research Articles

Automated precision counting of small lunar craters - A broader view

An automated system for counting small craters at lunar landing sites has been expanded to include selected locations on the Moon's far side and high latitudes. Highland areas were generally excluded from this new survey, because sloping terrain can have a significant effect on crater lifetimes. But some locations on highland light plains units were analysed, as were some young Copernican age crater ejecta blankets and impact melts.This study focuses on craters having diameters between 2.5 m and 50 m, for which counts are so high that they are best plotted as Crater Size Frequency Histograms (CSFHs), rather than the conventional cumulative plots (CSFDs). This histogram representation enables the finest details of the plots to be compared across sites. Using multiple precisely aligned images of each site enables false negatives to be included and false positives rejected, ensuring that no visually recognisable craters are missed, a capability that is not possible when analysing single images.There are some very distinct differences between the curves at different sites. Based on the known ages of boulder tracks and counts of craters formed over the last 50 years, the largest craters within the size range up to 50 m are thought to be no more that a few hundred million years old. A model for the evolution of small crater populations on an absolute time scale is presented and the absolute ages of young features are estimated.There is no evidence in the data for secondary cratering, nor is there any clear variation of counts and slopes with longitude or latitude, so other possible explanations for the variabilities between sites must be found.The results obtained by this project should prove useful for modelling crater formation and destruction and also as training data for machine learning systems.

Layered Structures in the Upper Several Hundred Meters of the Moon Along the Chang'E‐4 Rover's First 1,000‐m Traverse

AbstractWe revealed the layered structure of the upper three hundred meters of the lunar surface in the South Pole‐Aitken Basin by using the measurements from the Lunar Penetrating Radar (LPR) onboard the Chang'E‐4 rover. The result shows that five large strata are identified by the LPR 60‐MHz channel below the depth of 90 m, with thicknesses ranging from 20 m to larger than 70 m. We speculate that at least three strata are basalt flows, while the shallowest stratum is composed of multiple thin lava flows. The thickness of the strata decreases with the decreasing depth, suggesting a progressively smaller lava effusion rate over time. To evaluate the reliability of the result, a comparison was made between Chang'E‐4, Chang'E‐3, and ground test low‐frequency data. The LPR 500‐MHz channel unveiled the structure of weathered material in the top ∼40 m, revealing several layers as well as a buried paleo crater and its ejecta blanket in the regolith.

New Insights into Aristarchus Crater with LRO LAMP Far-ultraviolet Observations

Aristarchus crater is a Copernican-age impact crater well known for its high-albedo ejecta blanket and nearby flow features rich in pyroclastic materials. The Lyman Alpha Mapping Project (LAMP) is a far-ultraviolet (FUV) spectrograph (57–197 nm) on board the Lunar Reconnaissance Orbiter (LRO). LAMP data identified Aristarchus crater as having a high Off-band (155–184 nm) to On-band (130–155 nm) albedo (Off/On) ratio, providing new insight into the mineral composition of the area. Previous LAMP observations of bright crater rays and lunar swirls show that regions of high Off/On-band ratios may indicate highly feldspathic compositions. In this study we use LAMP data to understand FUV compositional signatures at Aristarchus. We investigate four well-characterized regions of interest around Aristarchus crater, and we compare Off/On-band ratios at Aristarchus crater to laboratory-derived ratios of several endmembers such as anorthite and olivine. We further analyze LAMP FUV spectra alongside near-infrared spectra from the Moon Mineral Mapper (M3) on board Chandrayaan-1 to characterize the mineralogy in several regions of interest. We find that LAMP Off/On-band ratios are able to distinguish between plagioclase feldspars and minerals such as quartz and mafic-dominated compositions. The LAMP Off/On-band ratios at Aristarchus are higher than previously reported ratios for plagioclase-rich regions, suggesting that the composition is unique to Aristarchus. Spectra from LAMP and M3 both show that the central peak and high-albedo ejecta around Aristarchus contain shocked, possibly alkalic, plagioclase feldspar.

The Spatial Distribution of the Unidentified 2.07 μm Absorption Feature on Europa and Implications for its Origin

A weak absorption feature at 2.07 μm on Europa’s trailing hemisphere has been suggested to arise from radiolytic processing of an endogenic salt, possibly sourced from the interior ocean. However, if the genesis of this feature requires endogenic material to be present, one might expect to find a correlation between its spatial distribution and the recently disrupted chaos terrains. Using archived near-infrared observations from the Very Large Telescope/SINFONI with a ∼1 nm spectral resolution and a linear spatial resolution ∼130 km, we examine the spatial distribution of this feature in an effort to explore this endogenic formation hypothesis. We find that, while the presence of the 2.07 μm feature is strongly associated with the irradiation pattern on Europa’s trailing hemisphere, there is no apparent association between the presence or depth of the absorption feature and Europa’s large-scale chaos terrain. This spatial distribution suggests that the formation pathway of the 2.07 μm feature on Europa is independent of any endogenous salts within the recent geology. Instead, we propose that the source of this feature may simply be a product of the radiolytic sulfur cycle or arise from some unidentified parallel irradiation process. Notably, the 2.07 μm absorption band is absent from the Pwyll crater ejecta blanket, suggesting that radiolytic processing has not had enough time to form the species responsible and placing a lower limit on the irradiation timescale. We are unable to find a plausible spectral match to the 2.07 μm feature within the available laboratory data.

Evidence for trail forming ejecta boulder falls around fresh simple impact craters at the lunar Orientale multi-ring basin and implications for ballistic ejecta sedimentation on the Moon

The topographic slopes of the Moon host different types of mass wasting features, in which boulder falls are abundant globally. Boulder falls are characterized by trails that are produced by rolling, bouncing and sliding of boulders on the lunar surface, in response to ground shaking originating from shallow moonquakes, impact events and other surface processes. Our previous work showed evidence for moonquake-triggered boulder falls at hundreds of sites on the interior of Orientale multi-ring basin. In this study, we document new evidence for ejecta boulder falls around 135 fresh simple impact craters with diameters ranging from 0.1 to 2.5 km in the same basin. Our detailed characterization of ejecta boulder falls around eight selected impact craters reveal their modes of occurrences, morphological properties, formation ages and clues to their impact origins. The ejecta boulder falls have the characteristic boulder trails arranged radially around the host impact craters, shorter trail lengths, narrow trail widths and shallow trail depths, when compared to the moonquake-triggered boulder falls in the same basin. Some impact craters exhibit radial asymmetry of boulder trails around these craters because of oblique impacts, in which longer trails are abundant in down-range directions, while fewer and shorter trails characterize up-range directions. In some cases, local slopes also contribute to increased trail lengths and deviation from radial distribution of trails. Formation ages of a few host impact craters, determined based on conventional crater counting method, are in the range of 0.94–6.4 Ma, and the age of ejecta boulder falls is consistent with the host impact crater ejecta. These characteristics suggest that the trails were produced by the ejecta boulders, during the ejecta blanket formation stage of the host impact craters. The relationship between the host impact crater diameter and the average size of large ejecta boulders present in their ejecta blankets suggests that the host impact craters are primary impact craters. Hence, the initial ejecta boulder fall velocities are expected to be in the ejection velocity range of ∼5–100 m/s. During ballistic sedimentation, these ejecta boulders erode the local target materials including regolith and mix them along their trails. It is also observed that ejecta boulder falls occur around small fresh simple impact craters (<2–3 km) at the Schrödinger and Lorentz basins. Around large size impact craters and basins, ejecta boulder falls produced large-size radial grooves, lineaments and sculptures on the Moon. We conclude that the characteristics of ejecta boulder falls and moonquake boulder falls are distinctly different from each other, reflecting their distinct formation conditions, but these form contemporaneously on the Moon.

Tesserae: Surface differences across Venus’s “continents”

The heavily deformed upland tesserae are some of the most ancient geologic units on Venus and, as such, record the longest history of surface evolution. Our geologic understanding of these landforms is based largely on radar images from the Magellan mission, in which gross morphology and small-scale properties can be difficult to deconvolve. Here we use Magellan radar backscatter data for ridge slope surfaces in 22 highland areas to understand whether the tesserae can be subdivided in ways that differentiate surface property variations. Significant variations occur in the mean backscatter of ridge slopes, and we divide the tesserae into two groups with echoes lower (n = 15) or higher (n = 7) than an average tessera radar scattering behavior. While both few-kilometers-scale slopes and centimeter-scale roughness can modulate the radar returns, at least seven out of 15 tesserae with lower echoes are correlated with fine-grained impact crater ejecta deposits that smooth the surface. We propose that distal ejecta deposition plays a major role in creating the observed range of tessera radar properties and obscuring aspects of their original formation and in situ weathering. Our twofold classification system provides a new way of assessing the physical characteristics of tesserae from the Magellan data. Upcoming missions must consider both their original morphology and post-emplacement processes if we are to unlock the geologic record preserved in tesserae.

Provenance of altered carbon phases and impact history of the Stac Fada Member, NW Scotland

AbstractThe Stac Fada Member (Stoer Group) is a ~1.2 Ga melt‐rich impact breccia preserved and intermittently exposed along the NW coast of Scotland. Using a combination of x‐ray diffraction and micro‐Raman spectroscopy, we identify potential coesite that is spatially associated with micron‐sized diamonds, as well as disordered carbon phases. Comparing the graphite G‐band of disordered carbon phases in the impact breccia to samples from underlying units indicates that most of the carbon in the Stoer Group was ultimately derived from the underlying Lewisian basement. Disordered carbon phases within the Stac Fada Member have been modified by mild heating within a hot ejecta blanket rather than shock pressure. We also report the first evidence for impact diamonds discovered within the Stac Fada Member. These diamonds have an average Raman shift of 1328.5 cm−1 and are present within both the impact breccia and the shocked gneiss clasts that are present in sandstones directly underlying the Stac Fada Member contact, and within sandstone rafts entrapped in the unit. These findings have implications for the timing of deposition of the Stac Fada Member, which must have occurred after ballistic ejection of Lewisian basement clasts during the impact event.

The Proximal Ejecta Around the Marine‐Target Lockne Impact Structure, Sweden

AbstractVery few impact craters on Earth have preserved proximal ejecta (ejecta blanket), which when present help us to better understand the cratering processes when asteroid hits Earth. The 458 Ma old Lockne impact structure consists of a 7.5‐km wide nested crater in the crystalline basement surrounded by an approximately 3‐km wide brim developed in the upper sedimentary target. The asteroid struck a marine environment with 500 m sea water, 50‐m lithified limestone, and 30 m of Cambrian clay covering a peneplainized crystalline basement. The transient crater that developed in rock and water obtained a “soup‐plate” shape and reached about 7 km from the impact crater center, the farthest on the down‐range side. The brim of the soup‐plate was partially stripped of Ordovician limestone and water before the emplacement of inner impact crater ejecta. Most of the ejecta rest upon the Cambrian clay (today shale). The asteroid struck obliquely from the east, which is reflected in the ejecta distribution. The proximal ejecta field is divided into two crescent‐shaped areas to the northwest and southwest of the nested crater and covers 26 km2. Resistivity profiles, mapping, and core drilling show that the thickness of the ejecta masses range between 30 and 50 m with a total volume of about 1 km3. They were not re‐worked by the resurge. They represent roughly 26 vol% of the calculated excavated volume of crystalline rocks. Thus, it can be concluded that the Lockne impact crater has a well‐preserved ejecta blanket.

Lunar Surface Model Age Derivation: Comparisons Between Automatic and Human Crater Counting Using LRO‐NAC and Kaguya TC Images

AbstractDating young lunar surfaces, such as impact ejecta blankets and terrains associated with recent volcanic activities, provides critical information on the recent events that shaped the surface of the Moon. Model age derivation of young or small areas using a crater chronology is typically achieved through manual counting, which requires a lot of small impact craters to be tediously mapped. In this study, we present the use of a Crater Detection Algorithm (CDA) to extract crater populations on Lunar Reconnaissance Orbiter—Narrow Angle Camera (LRO‐NAC) and Kaguya Terrain Camera images. We applied our algorithm to images covering the ejecta blankets of four Copernican impact craters and across four young mare terrains, where manually derived model ages were already published. Across the eight areas, 10 model ages were derived. We assessed the reproducibility of our model using two populations for each site: (a) an unprocessed population and (b) a population adjusted to remove contaminations of secondary and buried craters. The results showed that unprocessed detections led to overestimating crater densities by 12%–48%, but “adjusted” populations produced consistent results within &lt;20% of published values in 80% of cases. Regarding the discrepancies observed, we found no significant error in our detections that could explain the differences with crater densities manually measured. With careful processing, we conclude that a CDA can be used to determine model ages and crater densities for the Moon. We also emphasize that automated crater datasets need to be processed, interpreted and used carefully, in unity with geologic reasoning. The presented approach can offer a consistent and reproducible way to derive model ages.

The Rock Abundance of Crater Populations as a Probe of Mare Protolith Properties

AbstractThe volcanic parent rock (“protolith”) composing the lunar maria is likely to have developed diverse mechanical properties upon emplacement. The abundance of rocks ejected by impacts may be sensitive to protolith properties. We investigate the relationship between the possible diversity of mare protoliths and the abundance of rocks excavated and emplaced by impacts employing cumulative size‐frequency distributions (SFDs) of rocky craters in the maria. The SFDs of 15 mare units were calculated through varying degrees of Lunar Reconnaissance Orbiter Diviner‐derived rock abundance within crater ejecta blankets. By inspecting the frequency of high rock abundance craters, we find that the age of a surface does not control an impactor's ability to excavate rocks. Through analysis of SFDs, we find that differences in SFD behavior may act as probes for the mechanical strength of the protolith and the thickness of buried lava flows. Generally, regions with SFDs that have shallower slopes with increasing rockiness may be associated with thick, competent flow types, and regions with SFDs that have unchanging slopes with increasing rockiness may be associated with stacked, thin flows that are possibly more friable. The greater frequency of high rock abundance craters and the converging behavior of SFDs at two units within Mare Humorum and Oceanus Procellarum suggest that the surfaces are underlain by thick, competent lava flows. Finally, SFD slope analysis suggests that secondary impact craters are relatively ineffective at excavating rocks and the SFDs of rocky craters may reflect primary cratering populations.

Lunar collision rate with primordial black holes

ABSTRACT A recent letter studied cratering during collisions between rocky bodies and primordial black holes. Hydrodynamic simulations in that work showed that ejecta blankets from these collisions are steeper because the black holes completely penetrate the target, potentially making these craters distinguishable from traditional point-like impactors. This may allow us to use lunar craters to constrain primordial black holes in the asteroid-mass window, about 1017–1019 g. In this work, we calculate the lunar dark matter flux from the Galactic halo and several models for a dark disc. We consider several effects that may enhance the dark matter flux, such as gravitational focusing on the Solar system and historical modulations due to the Solar system’s galactic orbit. We find that non-detection of novel craters on the Moon can constrain relativistic compact MACHO dark matter up to 1017 g at 95 per cent confidence, motivating a detailed search through lunar surface scans. In addition, we show that fluxes near Earth from dark discs may be significantly enhanced by gravitational focusing and that the relative velocity between the disc and the Sun can result in annual modulations out of phase with the annual modulations from the halo.

A Theory about a Hidden Evander-Size Impact and the Renewal of the Intermediate Cratered Terrain on Dione

The study introduces a theory about an Evander-size impact on the surface of Dione. Our study suspects a relatively low-velocity (≤5 km/s) collision between a ca. 50–80 km diameter object and Dione, which might have resulted in the resurfacing of one of the satellite’s intermediate cratered terrains in various ways, such as surface planing by “plowing” by ricocheting ejectiles, ejecta blanket covering, partial melting, and impact-triggered diapir formation associated with cryotectonism and effusive cryo-slurry outflows. Modeling the parameters of an impact of such a size and mapping the potential secondary crater distribution in the target location may function as the first test of plausibility to reveal the location of such a collision, which may be hidden by younger impact marks formed during, e.g., the Antenor, Dido, Romulus, and Remus collision events. The source of the impactor might have been Saturn-specific planetocentric debris, a unique impactor population suspected in the Saturnian system. Other possible candidates are asteroid(s) appearing during the outer Solar System’s heavy bombardment period, or a collision, which might have happened during the “giant impact phase” in the early Saturnian system.

Linking a distal ejecta with its source crater: a probabilistic approach applied to tektites

We propose a probabilistic approach to gauge the plausibility of a genetic link between a distal ejecta and a known impact structure, considering the only possible alternative that the distal ejecta could originate from an unknown impact site. We exemplify this approach in the case of three tektite strewn fields related to three known impact structures—the belizites, related to Pantasma (Nicaragua), the ivorites, related to Bosumtwi (Ghana), the moldavites, related to Ries (Germany), as well as on Manson crater ejecta. The computed probability for the unknown meteoritic impact is about 1% or less for these four cases studies.

Investigating the relaxation of small craters emplaced on solidified melt sheets on the Moon

Larger impact craters and basins on the Moon display a persistent discrepancy in crater size frequency distributions between their interior melt surfaces and exterior ejecta blankets. The population of smaller craters <1 km across used to date the melt and ejecta surfaces often indicate younger surface ages for the melt surface, even though the two should be the same age having formed at the same time from the initial impact. This work investigates the possibility of removal or deformation of these small craters by topographic relaxation via the solid-state creep of lunar mare and highlands materials that have formed on a warm but recently solidified melt sheet on the Moon. We first determine the thermal state of a solidified volume of melt as it cools from the surface to a melt interface at depth that is thick enough to accommodate the emplacement of craters 200 m or 500 m in diameter. We then examine the extent of topographic relaxation under a favorable steady state temperature profile using material rheologies for the applicable lunar materials under lunar gravity. Ultimately, our simulations show that despite elevated thermal conditions that are favorable to relaxation, the low stress state and stiffness of the material rheologies inhibit any significant crater deformation, with displacements <1 m over 10 kyr. This finding suggests that other mechanisms such as self-secondary cratering or target material contrasts, among others and possibly in combination, are likely responsible for the discrepancy in CSFD ages between the melt and ejecta surfaces.

Untrackable distal ejecta on planetary surfaces

Impact ejecta are important references to establish regional and global stratigraphy of planetary bodies. Canonical views advocate radial distributions of distal ejecta with respect to the source crater, and their trajectories are significantly deflected on fast-rotating bodies. The Hokusai crater on Mercury formed a peculiar ray that features a hyperbola shape, and the sharp swerve of orientation was interpreted as a sign of a faster planetary rotation in the near past. Here, we show that this ray was not caused by a hypothesized larger Coriolis force, but due to abruptly-steepened ejection angles. Heterogeneous shock impedances of pre-impact impactor and/or target, such as topographic undulations, affect local propagation paths of shock and rarefaction waves, causing sudden changes of ejection angles. Distal ejecta with non-radial distributions are an inherent product of planetary impacts, and their unobvious provenances could mislead stratigraphic interpretations and hamper age estimations based on spatial densities of impact craters.

Permafrost molards as an analogue for ejecta-ice interactions at Hale Crater, Mars

When the Hale impact crater penetrated the martian cryosphere 1Ga, landforms indicating post-impact volatile mobilisation were generated. We have found landforms in the ejecta blanket of Hale Crater similar to ‘permafrost molards’ found in periglacial environments on Earth, and probably related to the past or present presence of volatiles at/near the surface. Permafrost molards are conical mounds of debris associated with landslide deposits, resulting from the degradation of blocks of ice-rich material mobilised by a landslide in periglacial terrains. Here we analyse the spatial and topographic distribution of conical mounds around the Hale crater at regional and local scales, and compare them to those of molards on the deposits of the Mount Meager debris avalanche in Canada. Hale Crater's conical mounds are located at the distal boundary of the thickest ejecta blanket, which is the closest to the main crater. We observe a similar spatial arrangement of molards along the distal parts of the terminal lobe of the Mount Meager debris avalanche. We then compare the morphology and morphometrics of the conical mounds on Hale Crater to those of terrestrial molards on the Paatuut and Niiortuut rock avalanches in western Greenland. We find that morphology and setting of conical mounds within Hale Crater ejecta are consistent with the formation pathway of molards on Earth. We infer that they originated from blocks of ice-cemented regolith that were produced by the Hale-crater-forming impact, transported by the ejecta flows, and finally degraded to cones of debris (molards) on loss of the interstitial ice. The similarities in distribution between the ejecta flows of Hale and Mount Meager debris avalanche on Earth suggest that the mounds resulted from the rheological separation of the ejecta flows, with a relatively fluid-poor phase that allowed the volatile-rich blocks to survive transport. This supports the prevailing hypothesis that the Hale impact event penetrated the martian cryosphere, providing important constraints on the rheology of martian ejecta deposits.

Understanding the mineralogy of a compositional anomaly north of the Korolev basin using Moon mineralogy mapper

The work attempts to understand the mineralogy of the reported geochemical anomaly located in the north – northeast region of the Korolev basin using Moon Mineralogy Mapper (M3) onboard Chandrayaan −1 and other lunar datasets. To understand the mineralogy, colour composite images using integrated band depth parameters and mineral indices were prepared, and the M3 spectral signatures corresponding to the unique colours of these colours composites were investigated. Further, Modified Gaussian Model (MGM) deconvolution was applied to these spectra. The results of spectra studies reveal that the area is made up of heterogeneous lithologies, predominantly composed of anorthosite along with minor occurrences of pyroxene-bearing (both low-calcium and high-calcium variety) and spinel-bearing lithologies. Correlation of spectral studies with the morphology revealed that pyroxene was typically associated with fresh craters and their ejecta. Spinel was found to be ubiquitous and is well-dispersed, possibly distributed along with the ejecta blanket of large impact craters. This association hints that the pyroxene-hosted layer most likely occurs beneath the spinel-bearing layer. Such observed assemblages may have resulted from physical mixing during the impact cratering events. This mixed lithology could arise due to the mafic mineral-bearing ejecta of the South-Pole Aitken (SPA) basin and spinel-bearing Orientale ejecta. Korolev most likely impacted on a thick layer of SPA ejecta, and impact basins such as Hertzsprung and Orientale have occurred post-Korolev formation. Orientale being the youngest of the large impact basins, its ejecta carrying the light plain material would have overprinted the older SPA ejecta. Smaller impact craters would have churned the ejecta so that presently we observe a composite lithology with a variable abundance of pyroxene and spinel.

Quest for the Australasian impact crater: Failings of the candidate location at the Bolaven Plateau, Southern Laos

AbstractThe quest for the parent impact structure for Australasian tektites (AAT) has remained without solution for almost a century. The present paper doubts the plausibility of the recently proposed location of the impact site at the Bolaven volcanic field in Southern Laos by showing problems with most of the presented lines of evidence. The geochemical incompatibility of the AAT composition with a mixture of weathered basalts and Mesozoic sandstones that were proposed as source materials of AAT is demonstrated by a two‐component mixing calculation for major element oxides and the Nd‐Sr isotopic system. Deficiency of the basaltic component as a source of Ni, Co, Cr, and 10Be in AAT and inconsistency with trends observed for O and Pb isotopes are shown. The size of the putative crater, conclusiveness of a gravity anomaly identification, signs of complete crater burial by postimpact lava flows, and identification of proximal ejecta blanket are doubted. Remarks on the shortcomings of the current consensus location of an impact site for AAT in Indochina are presented.

Degradation of the Lunar Surface by Small Impacts

The surfaces of airless bodies like the Moon are bombarded by a steady stream of small impactors that lead to erosion of the topography over time. However, the rate of degradation from small impacts, a key parameter in interpreting the ages of present-day lunar surface features, is not well constrained. Here we demonstrate, using a numerical mass transport model, that impact erosion is a nonlinear diffusion process, in contrast to past studies of crater degradation that have assumed that the downslope mass flux of ejecta is linearly proportional to hillslope gradient. Nonlinearity is a consequence of the asymmetric shape of ejecta blankets on sloped surfaces, and as a result, the degradation rate on steep slopes is over 40% greater than on nearly flat surfaces. Using measurements of the morphology and formation rate of small primary and secondary craters, the kilometer-scale lunar landscape diffusivity is computed and compared to the value inferred from topographic profiles of degraded craters. We show that the abundance of decameter-scale craters forming on the Moon over the past decade is consistent with small impacts dominating the erosion of the lunar landscape, but only if the primary size−frequency distribution remains steep down to the submillimeter scale.

On the provenance of the Chang'E-5 lunar samples

China's Chang'E-5 (CE-5) mission has collected 1.731 kg samples from a young mare basalt unit (named P58/EM4) in the northeastern Oceanus Procellarum region of the Moon. Accurate tracing of the provenance of returned samples is essential for understanding their laboratory measurements, which can provide critical information about the Moon and the inner Solar System. In this article, the provenance, chemical composition, formation, and evolution processes of the regolith at the CE-5 landing site are analyzed by using remote sensing observations and crater ejecta deposition models. A comprehensive search based on crater ejecta thickness model shows that 1892 impact craters in P58 likely deposited ∼0.56 m of primary ejecta at the landing site, whereas 4 impact craters outside P58 deposited 0.05 m of distal ejecta that further excavated and reworked ∼0.5 m thick local mare basalt. Twelve craters within 1 km from the CE-5 landing site are estimated to contribute ∼0.49 m (~88%) of the ejecta materials, and their ejecta source regions are investigated using the Maxwell Z model. Among these 12 craters, Xu Guangqi and a smaller crater near the landing site are the two most volumetrically significant contributors (~0.3 m and ∼0.12 m). Craters more than 1 km distant from the landing site deposited fewer exotic materials, but some of them could have delivered low-Ti materials to the sampling site. Finally, the regolith stratigraphy at the landing site is investigated based on the identified and assumed impact sequence by using a Monte Carlo-based ejecta ballistic sedimentation model. The results reveal a depth-varying FeO/TiO2 abundance profile at the landing site, suggesting that the sedimentation of distant ejecta can reduce FeO/TiO2 abundance of the underlying layer by ∼1 wt.% at ∼0.5 m depth. Our results provide key information on sample provenance and regolith stratigraphy of the landing site, which is crucial to deciphering the returned CE-5 samples.