Martian cratering 12. Utilizing primary crater clusters to study crater populations and meteoroid properties

Images from Mars Global Surveyor and later images from Mars Reconnaissance Orbiter reveal that roughly half of the meteoroids striking Mars (at meter to few decameter crater diameters) fragment in the Martian atmosphere, producing small clusters of primary impact craters. Statistics of these “primary clusters” yield valuable information about important Martian phenomena and properties of interplanetary bodies, including meteoroid behavior in the Martian atmosphere, bulk strengths of bodies striking Mars, and the fraction of Martian “field secondary” craters, a datum that would improve crater count chronometry. Many Martian impactors fragment at altitudes significantly higher than 18 km above the mean surface of Mars, and we find that most bodies striking Mars and Earth have low bulk strengths, consistent with crumbly or highly fractured objects. Applying statistics of primary clusters at various elevations and independent diameter bins, we describe a technique to estimate the percentage of semirandomly scattered “field secondary” craters. Our provisional estimate of this percentage, in the diameter range ~250 m down to ~22 m, is ~40% to ~80% of the total impacts, with the higher percentages at smaller diameters. Our data argue against earlier suggestions of overwhelming dominance by either primaries or secondaries in this diameter range.     

Nature of the Martian uplands: Effect on Martian meteorite age distribution and secondary cratering

Abstract— Martian meteorites (MMs) have been launched from an estimated 5–9 sites on Mars within the last 20 Myr. Some 80–89% of these launch sites sampled igneous rock formations from only the last 29% of Martian time. We hypothesize that this imbalance arises not merely from poor statistics, but because the launch processes are dominated by two main phenomena: first, much of the older Martian surface is inefficient in launching rocks during impacts, and second, the volumetrically enormous reservoir of original cumulate crust enhances launch probability for 4.5 Gyr old rocks. There are four lines of evidence for the first point, not all of equal strength. First, impact theory implies that MM launch is favored by surface exposures of near‐surface coherent rock (≤10² m deep), whereas Noachian surfaces generally should have ≥10² m of loose or weakly cemented regolith with high ice content, reducing efficiency of rock launch. Second, similarly, both Mars Exploration Rovers found sedimentary strata, 1–2 orders of magnitude weaker than Martian igneous rocks, favoring low launch efficiency among some fluvial‐derived Hesperian and Noachian rocks. Even if launched, such rocks may be unrecognized as meteorites on Earth. Third, statistics of MM formation age versus cosmic‐ray exposure (CRE) age weakly suggest that older surfaces may need larger, deeper craters to launch rocks. Fourth, in direct confirmation, one of us (N. G. B.) has found that older surfaces need larger craters to produce secondary impact crater fields (cf. Barlow and Block 2004). In a survey of 200 craters, the smallest Noachian, Hesperian, and Amazonian craters with prominent fields of secondaries have diameters of ?45 km, ?19 km, and ?10 km, respectively. Because 40% of Mars is Noachian, and 74% is either Noachian or Hesperian, the subsurface geologic characteristics of the older areas probably affect statistics of recognized MMs and production rates of secondary crater populations, and the MM and secondary crater statistics may give us clues to those properties.     

Crater geometry and ejecta thickness of the Martian impact crater Tooting

Abstract— We use Mars Orbiter Laser Altimeter (MOLA) topographic data and Thermal Emission Imaging System (THEMIS) visible (VIS) images to study the cavity and the ejecta blanket of a very fresh Martian impact crater ?29 km in diameter, with the provisional International Astronomical Union (IAU) name Tooting crater. This crater is very young, as demonstrated by the large depth/diameter ratio (0.065), impact melt preserved on the walls and floor, an extensive secondary crater field, and only 13 superposed impact craters (all 54 to 234 meters in diameter) on the ?8120 km² ejecta blanket. Because the pre‐impact terrain was essentially flat, we can measure the volume of the crater cavity and ejecta deposits. Tooting crater has a rim height that has >500 m variation around the rim crest and a very large central peak (1052 m high and >9 km wide). Crater cavity volume (i.e., volume below the pre‐impact terrain) is ?380 km³ the volume of materials above the pre‐impact terrain is ?425 km³. The ejecta thickness is often very thin (<20 m) throughout much of the ejecta blanket. There is a pronounced asymmetry in the ejecta blanket, suggestive of an oblique impact, which has resulted in up to ?100 m of additional ejecta thickness being deposited down‐range compared to the up‐range value at the same radial distance from the rim crest. Distal ramparts are 60 to 125 m high, comparable to the heights of ramparts measured at other multi‐layered ejecta craters. Tooting crater serves as a fresh end‐member for the large impact craters on Mars formed in volcanic materials, and as such may be useful for comparison to fresh craters in other target materials.     

Martian cratering 8: Isochron refinement and the chronology of Mars

This paper reviews and refines the technique of dating martian surfaces by using impact-crater isochrons (defined as size distributions of impact craters on undisturbed martian surfaces of specified ages). In the 1970s, this system identified not only abundant ancient martian volcanic surfaces, but also extensive lava plains with ages of a few 10⁸ y-old; this dating was initially controversial but confirmed in the 1980s and 90s by martian meteorites. The present update utilizes updated estimates of the Mars/Moon cratering ratio (the most important calibration factor), improves treatment of gravity and impact velocity scaling effects, combines aspects of the crater size distribution data from earlier work by both Neukum and Hartmann, and for the first time applies a correction for loss of small meteoroids in the martian atmosphere from Popova et al. (2003, Meteorit. Planet. Sci. 38, 905-925). The updated isochrons are not radically different from the previous “2002 iteration” but fit observed data better and give somewhat older model ages for features dated from small craters (diameter D<100 m). Crater counts from young lava flows in various areas give good fits to the new isochrons over as much as 3 orders of magnitude in D, confirming the general isochron shape and giving crater retention ages in the range of some 10⁶ to some 10⁸ y, interpreted as lava flow ages. More complex, older units are also discussed. Uncertainties are greatest if only small craters (D?100 m) are used. Suggestions by other workers of gross uncertainties, due to local secondary craters and deposition/exhumation, are discussed; they do not refute our conclusions of significant volcanic, fluvial, and other geologic activity in the last few percent of martian geologic time or the importance of cratering as a tool for studying processes such as exhumation. Indeed, crater count data suggest certain very recent episodes of deposition, exhumation, and ice flow, possibly associated with obliquity cycles of ∼¹⁰⁷ y timescale. Evidence from ancient surfaces suggests higher rates of volcanism, fluvial activity, glaciation, and other processes in Noachian/Hesperian time than in Amazonian time.     

The rayed crater Zunil and interpretations of small impact craters on Mars

A 10-km diameter crater named Zunil in the Cerberus Plains of Mars created ∼¹⁰⁷ secondary craters 10 to 200 m in diameter. Many of these secondary craters are concentrated in radial streaks that extend up to 1600 km from the primary crater, identical to lunar rays. Most of the larger Zunil secondaries are distinctive in both visible and thermal infrared imaging. MOC images of the secondary craters show sharp rims and bright ejecta and rays, but the craters are shallow and often noncircular, as expected for relatively low-velocity impacts. About 80% of the impact craters superimposed over the youngest surfaces in the Cerberus Plains, such as Athabasca Valles, have the distinctive characteristics of Zunil secondaries. We have not identified any other large (?10 km diameter) impact crater on Mars with such distinctive rays of young secondary craters, so the age of the crater may be less than a few Ma. Zunil formed in the apparently youngest (least cratered) large-scale lava plains on Mars, and may be an excellent example of how spallation of a competent surface layer can produce high-velocity ejecta (Melosh, 1984, Impact ejection, spallation, and the origin of meteorites, Icarus 59, 234-260). It could be the source crater for some of the basaltic shergottites, consistent with their crystallization and ejection ages, composition, and the fact that Zunil produced abundant high-velocity ejecta fragments. A 3D hydrodynamic simulation of the impact event produced 10¹⁰ rock fragments ?10 cm diameter, leading to up to 10⁹ secondary craters ?10 m diameter. Nearly all of the simulated secondary craters larger than 50 m are within 800 km of the impact site but the more abundant smaller (10-50 m) craters extend out to 3500 km. If Zunil is representative of large impact events on Mars, then secondaries should be more abundant than primaries at diameters a factor of ∼1000 smaller than that of the largest primary crater that contributed secondaries. As a result, most small craters on Mars could be secondaries. Depth/diameter ratios of 1300 small craters (10-500 m diameter) in Isidis Planitia and Gusev crater have a mean value of 0.08; the freshest of these craters give a ratio of 0.11, identical to that of fresh secondary craters on the Moon (Pike and Wilhelms, 1978, Secondary-impact craters on the Moon: topographic form and geologic process, Lunar Planet. Sci. IX, 907-909) and significantly less than the value of ∼0.2 or more expected for fresh primary craters of this size range. Several observations suggest that the production functions of Hartmann and Neukum (2001, Cratering chronology and the evolution of Mars, Space Sci. Rev. 96, 165-194) predict too many primary craters smaller than a few hundred meters in diameter. Fewer small, high-velocity impacts may explain why there appears to be little impact regolith over Amazonian terrains. Martian terrains dated by small craters could be older than reported in recent publications.     

Ries and Chicxulub: Impact craters on Earth provide insights for Martian ejecta blankets

Abstract— Terrestrial impact structures provide field evidence for cratering processes on planetary bodies that have an atmosphere and volatiles in the target rocks. Here we discuss two examples that may yield implications for Martian craters: 1. Recent field analysis of the Ries crater has revealed the existence of subhorizontal shear planes (detachments) in the periphery of the crater beneath the ejecta blanket at 0.9–1.8 crater radii distance. Their formation and associated radial outward shearing was caused by weak spallation and subsequent dragging during deposition of the ejecta curtain. Both processes are enhanced in rheologically layered targets and in the presence of fluids. Detachment faulting may also occur in the periphery of Martian impacts and could be responsible for the formation of lobe‐parallel ridges and furrows in the inner layer of double‐layer and multiple‐layer ejecta craters. 2. The ejecta blanket of the Chicxulub crater was identified on the southeastern Yucatán Peninsula at distances of 3.0–5.0 crater radii from the impact center. Abundance of glide planes within the ejecta and particle abrasion both rise with crater distance, which implies a ground‐hugging, erosive, and cohesive secondary ejecta flow. Systematic measurement of motion indicators revealed that the flow was deviated by a preexisting karst relief. In analogy with Martian fluidized ejecta blankets, it is suggested that the large runout was related to subsurface volatiles and the presence of basal glide planes, and was influenced by eroded bedrock lithologies. It is proposed that ramparts may result from enhanced shear localization and a stacking of ejecta material along internal glide planes at decreasing flow rates when the flow begins to freeze below a certain yield stress.     

Martian cratering revisited: Implications for early geologic evolution

Improved crater statistics from varied Martian terrains are compared to lunar crater populations. The distribution functions for the average Martian cratered terrain and the average lunar highlands over the diameter range 8–2000 km are quite similar. The Martian population is less dense by approximately 0.70 from 8 to 256 km diameter and diverges to proportionally lower densities at greater diameters. Crater densities on Martian “pure” terra give a lower limit to the Mars/Moon integrated crater flux of 0.75 since the last stabilization of the respective planetary crusts. The crater population >8 km diameter postdating the Martian northern plains is statistically indistinguishable from that population postdating the lunar maria. Monte Carlo simulations were performed to constrain plausible mechanisms of crater obliteration. The models demonstrate that if the crater density difference between the lunar and Martian terra has been due to resurfacing processes, random intercrater plains formation cannot be the sole process. If plains preferentially form in and obliterate larger craters, then the observed Martian distribution retains its “shape” as the crater density decreases. This result is consistent with the morphology of Martian intercrater plains.     

Investigating target versus impactor influences on Martian crater morphology at the simple‐complex transition

Comparing craters of identical diameter on a planet is an empirical method of studying the effects of different target and impactor properties while holding total impact energy nearly constant. We have analyzed the Martian crater population within a narrow diameter range (7 km < crater diameter < 9 km) at the simple‐complex crater transition using three approaches. We looked for correlations of morphology with surface geology using a global crater database and global geologic map. We examined selected regions in detail with high‐resolution images to further understand the relationship between crater morphology and bulk target properties. Finally, we examined craters in close proximity to each other in order to hold target properties constant, so that we could isolate impactor effects on crater morphology. We found a strong correlation between target properties and interior crater morphology, and we found little evidence that impactor properties (other than impact angle) affect crater appearance. Central uplift and wall slumping are enhanced for less consolidated targets. Layered targets affected both the excavation and modification stages of complex crater formation; the resulting craters have pseudoterraces, flat floors, and central pits.     

Areal distribution of Martian rampart craters

A survey of medium- and high-resolution Viking orbital imagery was carried out in order to characterize the areal distribution of Martian rampart craters. Such craters have been identified on nearly every major geologic unit on the planet, at all latitudes and longitudes, and over a wide range of altitudes. Rampart crater formation spans Martian geologic history from at least the formation of the Chryse channels to the present.     

Ridge systems related to Martian impact craters

Wrinkle ridge systems within and around Martian highland craters were studied in order to find their basin-induced and regional aspects. Most prominent ridge directions indicate regional tectonic patterns. Radial ridges near large craters are often slightly deflected along regional or global ridge systems. Crater floor ridges have simpler local distributions. Smaller or older craters are less resistant against the effects of global or regional stress systems. In craters concentric ridge rings locate at 0.8 crater radius with additional minor rings at 0.66, 0.44 and 0.94 crater radius. This pattern illustrates compression of lava fill over buried topography.     

Morphology and geometry of the distal ramparts of Martian impact craters

Abstract— We used Mars Orbiter Laser Altimeter (MOLA), Thermal Emission Imaging System visible light (THEMIS VIS), and Mars Orbiter Camera (MOC) data to identify and characterize the morphology and geometry of the distal ramparts surrounding Martian craters. Such information is valuable for investigating the ejecta emplacement process, as well as searching for spatial variations in ejecta characteristics that may be due to target material properties and/or latitude, altitude, or temporal variations in the climate. We find no systematic trend in rampart height that would indicate regional variations in target properties for 54 ramparts at 37 different craters 5.7–35.9 km in diameter between 52.3°S to 47.6°N. Rampart heights for multi‐lobe and single‐lobe ejecta are each normally distributed with a common standard deviation, but statistically distinct mean values. Ramparts range in height from 20–180 m, are not symmetric, are typically steeper on their distal sides, and may be as much as ?4 km wide. The ejecta blanket proximal to parent crater from the rampart may be very thin (<5 m). A detailed analysis of two craters, Toconao crater (21°S, 285°E) (28 measurements), and an unnamed crater within Chryse Planitia (28.4°N, 319.6°E) (20 measurements), reveals that ejecta runout distance increases with an increase in height between the crater rim and the rampart, but that rampart height is not correlated with ejecta runout distance or the thickness of the ejecta blanket.     

Martian subsurface properties and crater formation processes inferred from fresh impact crater geometries

Abstract— The geometry of simple impact craters reflects the properties of the target materials, and the diverse range of fluidized morphologies observed in Martian ejecta blankets are controlled by the near‐surface composition and the climate at the time of impact. Using the Mars Orbiter Laser Altimeter (MOLA) data set, quantitative information about the strength of the upper crust and the dynamics of Martian ejecta blankets may be derived from crater geometry measurements. Here, we present the results from geometrical measurements of fresh craters 3–50 km in rim diameter in selected highland (Lunae and Solis Plana) and lowland (Acidalia, Isidis, and Utopia Planitiae) terrains. We find large, resolved differences between the geometrical properties of the freshest highland and lowland craters. Simple lowland craters are 1.5–2.0 times deeper (≥5s?_o difference) with >50% larger cavities (≥2s?_o) compared to highland craters of the same diameter. Rim heights and the volume of material above the preimpact surface are slightly greater in the lowlands over most of the size range studied. The different shapes of simple highland and lowland craters indicate that the upper ?6.5 km of the lowland study regions are significantly stronger than the upper crust of the highland plateaus. Lowland craters collapse to final volumes of 45–70% of their transient cavity volumes, while highland craters preserve only 25–50%. The effective yield strength of the upper crust in the lowland regions falls in the range of competent rock, approximately 9–12 MPa, and the highland plateaus may be weaker by a factor of 2 or more, consistent with heavily fractured Noachian layered deposits. The measured volumes of continuous ejecta blankets and uplifted surface materials exceed the predictions from standard crater scaling relationships and Maxwell's Z model of crater excavation by a factor of 3. The excess volume of fluidized ejecta blankets on Mars cannot be explained by concentration of ejecta through nonballistic emplacement processes and/or bulking. The observations require a modification of the scaling laws and are well fit using a scaling factor of ?1.4 between the transient crater surface diameter to the final crater rim diameter and excavation flow originating from one projectile diameter depth with Z = 2.7. The refined excavation model provides the first observationally constrained set of initial parameters for study of the formation of fluidized ejecta blankets on Mars.     

Dating very young planetary surfaces from crater statistics: A review of issues and challenges

Determining the ages of young planetary surfaces relies on using populations of small, often sub-km diameter impact craters due to the higher frequency at which they form. Smaller craters however can be less reliable for estimating ages as their size-frequency distribution is more susceptible to alteration with debate as to whether they should be used at all. With the current plethora of meter-scale resolution images acquired of the lunar and Martian surfaces, small craters have been widely used to derive model ages to establish the temporal relation of recent geologic events. In this review paper, we discuss the many factors that make smaller craters particularly challenging to use and should be taken into consideration when crater counts are confined to small crater diameters. Establishing confidence in a model age ultimately requires an understanding of the geologic context of the surface being dated as reliability can vary considerably and limitations of the dating technique should be considered in applying ages to any geologic interpretation.     

Cratering on Mars I. Cratering and obliteration history

Computerized cratering-obliteration models are developed for use in interpreting planetary surface histories in terms of the diameter-frequency relations for craters classified by morphology. An application is made to a portion of the lunar uplands, revealing several episodes of blanketing, presumably due to the formation of some of the major basins.Application to Martian craters leads to the following picture of Martian cratering and obliteration history. During a probable period of intense early bombardment, craters were degraded by two processes: a depositional-type process connected with the declining cratering rate, and a process tending to flatten the largest craters (e.g., isostatic adjustment). During late stages of the early bombardment, or subsequent to it, there occurred a major relative episode of obliteration (probably atmosphere related), but it ceased concurrently with the massive (presumably volcanic) resurfacing of the cratered plains. Subsequent resurfacing episodes have occurred in the smooth plain terrains, but obliteration processes have been virtually absent in the low-latitude cratered terrains.Recent global Martian cratering interpretations of Hartmann and Soderblom are compared. Absolute cratering chronologies are only so good as knowledge of the absolute cratering flux on Mars. The crater data of Arvidson, Mutch, and Jones do not confirm the basis, whereby Soderblom requires the dominant Martian crater obliteration process to be coincident in time with the early bombardment. If the asteroidal-cometary impact flux on Mars has averaged five times the lunar flux during post-lunar-mare epochs, then the obliterative episode lasted about half a billion years and occurred about 1.5 × 10⁹ yr ago.     

Martian rampart and pedestal craters' ejecta-emplacement: Coprates quadrangle

Relationships between crater size and ejecta-blanket areal extents imply a maximum ejecta-blanket thickness or maximum rim height for Martian rampart craters. The limiting thickness is encountered only for craters exceeding 6 km diameter. Although smaller rampart craters have ejecta which appears to have undergone flow during emplacement, the larger craters have an additional component of flow, namely, internal flow of the ejecta caused by the greater weight of their thicker ejecta deposits. Pedestal craters most likely result from impacts into less volatile-rich substrates which produce a less fluidized ejecta and, consequently, no flow lobes.     

A conceptual model for explanation of Albedo changes in Martian craters

We propose a conceptual model to interpret AM/PM high albedo events (HAEs) in crater interiors at the Martian seasonal polar caps. This model consists of two components: (1) a relatively permanent high-albedo water–ice body exposed in a crater interior and (2) a variable crater albedo in response to aerosol optical depth, dust contamination, and H₂O/CO₂ frost deposits or sublimes in four phases, based on temperature and solar longitude changes. Two craters (Korolev crater of fully exposed water–ice layer and ‘Louth’ crater of partially exposed water–ice layer) are used to demonstrate the model. This model explains the HAEs and their seasonal changes and suggests that many crater-like features formed in the last episodic advance of the polar ice cap in the last high obliquity period should have water–ice exposed or covered. For the AM-only HAEs craters, there seems no need of a water–ice layer to be fully exposed, but a subsurface water–ice layer (or ice-rich regolith) is a necessary condition.     

An investigation of Martian northern high‐latitude and polar impact crater interiors: Atypical interior topographic features and cavity wall slopes

Abstract– We examine Martian northern high‐latitude and polar impact craters (NPICs) to better understand the north polar materials and polar processes. We examine topographic characteristics for 346 NPICs and compare them to global fit data (e.g., Garvin et al. 2003 ; Boyce and Garbeil 2007 ) as well as to a small set (N = 92) of southern high‐latitude and polar impact craters (SPICs). We find that the NPIC population above 57° N is significantly shallower than the global crater population. This suggests that the NPICs (1) were initially shallow due to target properties of polar geologic units; (2) were once deeper, but have been infilled due to polar processes; or (3) a combination of both. Indeed, many of the NPICs exhibit considerable noncentral peak interior topographic features (IFTs), which may be indicative of infilling processes. The NPIC IFTs also appear to display trends in their preferential orientation within the crater cavity; some SPICs display similar interior features, but do not show a clear preference in their orientation within the crater cavity. In addition, the NPIC population displays cavity wall slope trends that seem to indicate steepening of slopes with increasing crater diameter in comparison to the global slope trend ( Garvin et al. 2003 ). These trends suggest that the NPICs are unique in their geometry when compared to the global data set as well as with the SPICs further indicating that the north polar region may exhibit target properties and polar processes not seen in the south polar region or elsewhere on Mars.     

Impact crater formation in icy layered terrains on Mars

Abstract— We present numerical simulations of crater formation under Martian conditions with a single near‐surface icy layer to investigate changes in crater morphology between glacial and interglacial periods. The ice fraction, thickness, and depth to the icy layer are varied to understand the systematic effects on observable crater features. To accurately model impact cratering into ice, a new equation of state table and strength model parameters for H₂O are fitted to laboratory data. The presence of an icy layer significantly modifies the cratering mechanics. Observable features demonstrated by the modeling include variations in crater morphometry (depth and rim height) and icy infill of the crater floor during the late stages of crater formation. In addition, an icy layer modifies the velocities, angles, and volumes of ejecta, leading to deviations of ejecta blanket thickness from the predicted power law. The dramatic changes in crater excavation are a result of both the shock impedance and the strength mismatch between layers of icy and rocky materials. Our simulations suggest that many of the unusual features of Martian craters may be explained by the presence of icy layers, including shallow craters with well‐preserved ejecta blankets, icy flow related features, some layered ejecta structures, and crater lakes. Therefore, the cratering record implies that near‐surface icy layers are widespread on Mars.     

Impact craters in the northern hemisphere of Mars: Layered ejecta and central pit characteristics

Abstract— Mars Global Surveyor (MGS) and Mars Odyssey data are being used to revise the Catalog of Large Martian Impact Craters. Analysis of data in the revised catalog provides new details on the distribution and morphologic details of 6795 impact craters in the northern hemisphere of Mars. This report focuses on the ejecta morphologies and central pit characteristics of these craters. The results indicate that single‐layer ejecta (SLE) morphology is most consistent with impact into an ice‐rich target. Double‐layer ejecta (DLE) and multiple‐layer ejecta (MLE) craters also likely form in volatile‐rich materials, but the interaction of the ejecta curtain and target‐produced vapor with the thin Martian atmosphere may be responsible for the large runout distances of these ejecta. Pancake craters appear to be a modified form of double‐layer craters where the thin outer layer has been destroyed or is unobservable at present resolutions. Pedestal craters are proposed to form in an icerich mantle deposited during high obliquity periods from which the ice has subsequently sublimated. Central pits likely form by the release of vapor produced by impact into ice‐soil mixed targets. Therefore, results from the present study are consistent with target volatiles playing a dominant role in the formation of crater morphologies found in the Martian northern hemisphere.     

GT-57633 catalogue of Martian impact craters developed for evaluation of crater detection algorithms

Crater detection algorithms (CDAs) are an important subject of the recent scientific research. A ground truth (GT) catalogue, which contains the locations and sizes of known craters, is important for the evaluation of CDAs in a wide range of CDA applications. Unfortunately, previous catalogues of craters by other authors cannot be easily used as GT. In this paper, we propose a method for integration of several existing catalogues to obtain a new craters catalogue. The methods developed and used during this work on the GT catalogue are: (1) initial screening of used catalogues; (2) evaluation of self-consistency of used catalogues; (3) initial registration from three different catalogues; (4) cross-evaluation of used catalogues; (5) additional registrations and registrations from additional catalogues; and (6) fine-tuning and registration with additional data-sets. During this process, all craters from all major currently available manually assembled catalogues were processed, including catalogues by Barlow, Rodionova, Boyce, Kuzmin, and our previous work. Each crater from the GT catalogue contains references to crater(s) that are used for its registration. This provides direct access to all properties assigned to craters from the used catalogues, which can be of interest even to those scientists that are not directly interested in CDAs. Having all these craters in a single catalogue also provides a good starting point for searching for craters still not catalogued manually, which is also expected to be one of the challenges of CDAs. The resulting new GT catalogue contains 57,633 craters, significantly more than any previous catalogue. From this point of view, GT-57633 catalogue is currently the most complete catalogue of large Martian impact craters. Additionally, each crater from the resulting GT-57633 catalogue is aligned with MOLA topography and, during the final review phase, additionally registered/aligned with 1/256° THEMIS-DIR, 1/256° MDIM and 1/256° MOC data-sets. Accordingly, the resulting GT-57633 catalogue can successfully be used as a part of the framework for evaluation of CDAs.