On a less dramatic note, impacts and impact sites are ideal vectors to get the public interested in geology and space sciences. Many geoparks have been created around impact craters and have been used to foster public engagement in science. Amongst other themes, the proposed session will especially invite contributions concerning the following subjects:
• Impacts and the early history of the Solar System
• Impact structures as indicators of target properties and habitability
• Role of impacts in delivery and formation of the molecular building blocks for life
• Impact-generated habitats for life
• Environmental and ecological effects of impacts
• Impacts as threats for life and humankind
• Use of impact sites for geoconservation, education and outreach
First-time petrological and mineral-chemical studies of L6 chondrites from Bursa (Turkey) were done, and the conditions of shock metamorphism were justified. A new age of the zircon-reidite was determined at 4.2 Ga (U-Pb (TIMS)).
Gray gneisses, TTG, enderbate rocks, and amphibolites from Murmansk and Central Kola megablocks of the N-W part of the Fennoscandian Shield were dated using SHRIMP and U-Pb (TIMS) on zircon, with ages ranging 3.7-3.2 Ga.
Protoliths of country rocks, based on Sm-Nd data, reflect TDM values 3.0 to 3.5 Ga, with ɛNd values ranging from +2 to -3.
Concentrations of PGE and Ir anomalies were studied for the basement rocks of the continental crust using ICP-MS, reflecting an extraterrestrial (impact) contribution during the early formation stages of the two megablocks of the N-W part of the Fennoscandian Shield.
Additionally, the basement rocks show high concentrations of ore metals (ICP-MS data) such as Fe, Pt, Pd, Ni and other elements unusual for Earth rocks (Koeberl et.al, 2024; Treatise on Geochemistry, 2003; Van Kranendonk et.al, 2019).
This research was carried out in accordance with the research topics outlined in Scientific Research Contracts FMEZ-2024-0004. Many thanks to A.N. Larionov for the U-Pb (SHRIMP) analysis. Devoted to memory of the outstanding geochemistry Derald Wasserbourg from USA for artificial spike 205 Pb for U-Pb (TIMS) measurements single grains baddeleyite and zircon.
How to cite: Bayanova, T., Kaygısız, E., Drogobuzhskaya, S., Dokukina, K., and Kunakkuzin, E.: Bursa chondrite ( L6) about 4.2 Ga by U- Pb (TIMS ) the oldest (3.7 Ga) age of zircon (SHRIMP) and ICP-MS data on Ir anomaly (impact) for the continental crust of the N-W part of Fennoscandian Shield (Arctic region), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2328, https://doi.org/10.5194/egusphere-egu26-2328, 2026.
The Lockne crater (7–12 km) and its smaller companion Målingen (0.7 km) formed simultaneously at 458 Ma in a shallow sea, resulting in exceptional preservation of crater fill and near-field ejecta. Their paired formation constitutes the only confirmed terrestrial impact by a binary asteroid. The event is linked to a major Middle Ordovician breakup in the Main Asteroid Belt (~470 Ma), implying that the impacting bodies were rubble-pile aggregates. The marine setting, with seawater and sedimentary strata overlying a flat crystalline basement, represents an extreme case of layering with strong property-contrasts, known to influence crater morphology and produce concentric structures. Such effects also have relevance for Mars, where concentric craters can indicate sedimentary rock and former habitable environments.
At Lockne, an inner 7.5 km wide basement crater is surrounded by a shallow ~12 km outer crater recorded in the sedimentary target rocks. It formed by a shallow excavation flow prior to deposition of basement crater ejecta, and is offset downrange due to oblique impact. At Målingen, the 0.7 km basement crater’s ejecta distribution indicates a wider but poorly preserved outer crater. Lockne subsurface geology is known from 11 shallow cores to ~335 m depth, but this is estimated to represent only a third of the crater’s true depth.
Binary asteroids are commonly rubble-piles, and although ~16% of asteroids are observed to be binary, the fraction of rubble-piles is likely much higher because original companions may have been lost. Several aspects of the Lockne morphology, notably an abnormally wide shallow outer crater surrounding the basement crater, are interpreted as consequences of a rubble-pile impact in the stratified target.
Previous 3-D simulations of the Lockne impact used a monolithic impactor. For an impact at 45° and 15 km/s, these models indicate a ~600 m projectile and target water depth slightly less than the projectile diameter, producing a ~5 km transient basement crater. Målingen was estimated at ~150 m if massive. However, rubble-piles of this size may fragment during atmospheric entry forming a “pancake-like” cluster significantly wider than the original body. Such clustered impacts distribute more energy near the surface producing shallower, wider craters. Obliquity increases breakup, enhances near-surface energy release, and intensifies downrange asymmetry. Thus, a rubble-pile could produce a wider crater than a monolithic equivalent and potentially influence basement crater depth.
To investigate crater formation mechanisms, we performed impact experiments and numerical simulations of clustered impactors. Experiments were carried out with the EPIC single stage gas gun at CAB CSIC-INTA, Spain, to launch Delrin projectiles up to ~400 m/s. Clustered projectiles were made from weakly bonded 2 mm spheres to obtain equal mass to 20 mm solid reference projectiles, and high-speed cameras recorded both half-space and quarter-space impacts. Numerical modeling in iSALE-2D is ongoing, testing several rubble-pile configurations.
Acknowledgements: This work was supported by grant PID2021-125883NB-C22 by the Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/10.13039/501100011033 and by ‘ERDF A way of making Europe’, and the Spanish Research Council (CSIC) support for international cooperation I-LINK (#ILINK22061).
How to cite: Ormö, J., Sturkell, E., Solana Gonzalez, P., Herreros, I., Agrawal, V., and T. King, Jr., D.: Anatomy of a marine-target impact structure by a “rubble-pile” asteroid in field observations, impact experiments, and numerical simulation., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5048, https://doi.org/10.5194/egusphere-egu26-5048, 2026.
Introduction: Paleochannels have been identified,which are interpreted to be the result of melting of ice. A 30 km diameter impact basin in the Aeolis/Zephyria region near the dichotomy boundary is characterized by small valley networks (Fig. 1) that are partly located radial to the crater rim. Large glacial deposits, interpreted to be the remains of debris covered glaciers, have been identified in the area surrounding the crater. The spatial association between the crater and the paleochannels suggest that the impact was responsible for their formation.
Ejecta deposit: The release of water is initiated by the melting of ice from the deposition of hot ejecta deposits over its surface. Such a mechanism would generate fluvial features in the absence of a climatic regime favorable for fluvial activity.
Conclusions: I propose that the valley networks originated from the release of water due to the deposition of hot ejecta over ice deposits present in the area during the impact event. Glacial deposits have been identified elsewhere on Mars [1-6]. Water sources originate from the melting of
snow/ice deposits, extensive fluvial features in close proximity to the large crater in a region interpreted to have experienced significant glacial activity. The spatial relationship between the valleys and the main crater suggest, that they are related. The hot ejecta deposit associated with the impact provides an explanation for the melting of ice deposits that were present on
the plateau at the time of impact.
Fig. 1: Themis Image V05875001(left) and terrestrial analog (right, glacier and drainage
system, Svalbard, adapted from [7]), suggesting the action of glacial meltwater as a water
source for fluvial channels.
References: [1] Christensen, P. R. (2003) Nature 422, 45–48. [2] Dickson, J. L. et al. (2008) Geology36(5), 411–415 [3] Head, J. W. et al. (2006) Geophys.Res. Lett. 33, doi:10.1029/2005GL024360. L08S03.[4] Levy, J. S. et al. (2007) J. Geophys. Res. 112, doi:10.1029/2006JE002852. E08004. [5] Newsom, H.E. (1980) Icarus 44, 207–216. [6] Shean, D. E. et al.(2007) J. Geophys. Res. doi:10.1029/112,2006JE002761. E03004. [7] Evans, D. (2005), Hodder Arnold, 544pp.
How to cite: Nussbaumer, J.: Evidence for impact into ice-rich terrain and melting to produce glaciation in the Aeolis/Zephyria region, Mars., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5988, https://doi.org/10.5194/egusphere-egu26-5988, 2026.
Impacts during the Hadean heavy bombardment profoundly influenced Earth's early habitability, both frustrating and fostering conditions for life's origin through sterilization events and the creation of hydrothermal habitats. This study quantifies probabilistic "sweet-spot" windows for prebiotic chemistry and life's emergence, integrating impact-induced thermal perturbations with biochemical stability constraints in a comprehensive modeling framework.
We employ a well-tested three-dimensional numerical thermal model to simulate heat delivery to Earth's crust from asteroid impacts during late accretion (4.5–3.5 Ga). Simulations incorporate initial magma ocean scenarios, evolving crustal formation, and decreasing geothermal gradients. Bombardment parameters, including mass flux and size distributions, are derived from recent dynamical models informed by geochronology and geochemistry. Model outputs are validated against the Hadean zircon age spectra, providing constraints on impact flux and thermal history.
From these simulations, we calculate global habitable volumes, delineate coherent hydrothermal zones with steep thermal gradients conducive to prebiotic synthesis, quantify impact-driven localized sterilization, and apply Bayesian optimization for probabilistic "sweet-spot" analysis. Integrating hydrothermal activity, sterilization statistics, and thermal limits for biomolecule stability (e.g., RNA, proteins), we identify an optimal window for life's origin between approximately 4.4 and 4.3 Ga, postdating peak bombardment yet leveraging impact-generated habitats.
These findings highlight impacts' dual role in delaying yet enabling early life, align with emerging evidence for hydrothermal vents as cradles of biogenesis and recent molecular biology estimates placing the microbial community of the Last Universal Common Ancestor (LUCA) at ca. 4.2 Ga (4.09 - 4.33 Ga), and offer new insights into habitability of the Hadean Earth.
How to cite: Abramov, O., Medvegy, A., and Mojzsis, S. J.: Quantifying Habitability of the Hadean Earth: Impacts, Hydrothermal Systems, and Windows for Life's Emergence, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11758, https://doi.org/10.5194/egusphere-egu26-11758, 2026.
The surface of the Moon is shaped by the impact processes, with new ones being formed as we watch (Robinson et al., 2015, Speyerer et al. 2016, Fairweather et al. 2022, Rizos et al. 2026). Understanding the current impact rate is crucial for the safety of the future lunar missions, determining the rate of foreign material delivery, defining the space weathering rates, and better understanding the shallow seismic sources before new seismometers will be deployed there to probe the lunar crust (Yamada et al., 2011). Impacts of particles larger than a gram can sometimes be observed as lunar flashes (Ortiz et al., 2000) that are formed because a small fraction (<0.5%) of the impact energy is released as a flash of light.
Over 600 lunar flashes has been observed up to this point (Sheward et al., 2023). Those events last ∼10 ms to a ∼1 s (Bouley et al., 2012). To better determine the properties of the impactor, it is necessary to better constrain the energy partitioning during the observed impact flashes. This can be done by identifying and characterizing the craters formed because of such an event. Because those craters are in the order of meters, most of those craters are still unknown. In fact, only a couple of craters were unequivocally linked with a newly formed crater, e.g., an event on 17th March 2013 was shown to be associated with an 18.8 m diameter crater (Mark S. Robinson et al., 2015). Hundreds of recent craters were also identified based on pre- and post- impact pairs of LRO images (Speyerer et al. 2016).
Efforts to study these craters were limited by the absence of high-resolution, specifically targeted images. For example, LRO’s NAC with a ~0.5 m/px resolution at 50 km altitude only allows the identification of craters larger than a couple of meters in diameter, and to properly measure the properties of the craters, they need to be at least >>10 meters in diameter (Sheward et al., 2022). Unfortunately, there are only a couple of craters of this size.
MANI MISSION, approved in December 2025 for A/B1 mission stage by ESA, will map the lunar surface using high-resolution imagery and create detailed 3D maps of the Moon’s terrain with resolution of ~20 cm /px. It will be accomplished by employing a targeted multi-angular photoclinometric mapping approach to chart the Moon’s key regions of interest. Its goal is to acquire orbital images of the lunar surface, including the polar regions, at the highest possible resolution across a wide range of observation geometries. From these images, Máni will produce detailed maps of topography and reflectance properties at a resolution comparable to that of the images themselves.
This new dataset will allow us to characterize in 3D craters only a couple meters in diameter, and thus substantially improve our ability to understand the current impact rate on the Moon, the energy partitioning on airless bodies as well as use crater properties to back-engineer the properties of target rocks all over the Moon.
How to cite: Losiak, A. and the MANI team: Characterization of recent impact craters on the Moon by the upcoming MANI mission. , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14285, https://doi.org/10.5194/egusphere-egu26-14285, 2026.
Posters virtual: Mon, 4 May, 14:00–18:00 | vPoster spot 4
EGU26-8876 | ECS | Posters virtual | VPS27
A New Impact Model for The Norian, Late Triassic Manicouagan CraterMon, 04 May, 15:00–15:03 (CEST) vPoster spot 4
Abstract
Meteorite impacts can lead to significant disruptions of Earth’s systems, potentially affecting the planet's climate, ecosystems, and environment. The Manicouagan impact event is recorded by one of the largest impact craters of the Phanerozoic era, located in Quebec, Canada in the Grenville Province of the Canadian Shield, with a rim-to-rim diameter of 85–100 km. It has a precise age of 215.40 ± 0.16 Ma, yet its environmental aftermath remains poorly constrained, particularly any robust link to the Norian, Late Triassic extinction pulses or carbon-cycle perturbations. Here we present a new impact-Simplified Arbitrary Lagrangian-Eulerian (iSALE) hydrocode simulation against the Manicouagan’s target lithologies to constrain the most plausible impactor diameters and velocities that would reproduce the observed crater morphology. Three best-fit models of crater diameters and velocities of 7.2 km at 20 km s-1, 8.8 km at 15 km s-1, and 10.4 km at 12 km s-1 reproduced crater diameters of 90, 95, and 100 km, respectively. We calculated the kinetic energy delivered by each projectile, which is on the order of 1.17–1.27x1023 J. The calculated energy is sufficient to vaporize the entire projectile and a considerable amount of the upper target lithologies, and melt large volumes of the target rocks. We then estimated the mass of vapor released into the atmosphere by using scaling relations and assessed the potential post-initial settling of the vapor mass after condensation and re-entry to be ~5x1017 g. This exceeds the ~1016 g blackout threshold required to cause global cessation of photosynthesis, darkness, and cooling. Our results provide numerical assessments of the environmental consequences of the Manicouagan impact event and a framework for reassessing its potential role in Late Triassic biotic and climatic events.
Keywords
Manicouagan Impact Event, Hydrocode modeling, iSALE simulations, Late Triassic, Environmental consequences.
How to cite: Salem, S., Al-Suwaidi, A., and El-Maarry, M.: A New Impact Model for The Norian, Late Triassic Manicouagan Crater, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8876, https://doi.org/10.5194/egusphere-egu26-8876, 2026.
Posters virtual: Thu, 7 May, 14:00–18:00 | vPoster spot 4
EGU26-14985 | ECS | Posters virtual | VPS28
A rapid route for even big planets to get big moonsThu, 07 May, 14:24–14:27 (CEST) vPoster spot 4
Earth’s Moon is really big. Both the satellite and the giant impact that created it have played key roles in our planet’s evolution into a life-supporting world; stabilising the planet’s spin for a consistent climate, and driving the ocean tides that could stimulate prebiotic chemistry. Giant impacts are common across planet formation. So, as observational techniques improve, we might expect to find large moons among the now thousands of detected exoplanets, many of which are more massive than Earth. A barrier to this is that giant impacts onto larger planets create hotter debris disks of mostly vapour, especially for ice-rich worlds. This gas would drag any small growing moonlets to rapidly spiral down to the planet, prohibiting any large moons from forming out of the disk.
However, using high-resolution 3D smoothed particle hydrodynamics (SPH) simulations of giant impacts, we find that big moons can be immediately placed onto wide orbits, safely outside the thick, dragging disk. This could allow large rocky and even large icy worlds to gain a big moon.
This impact scenario had previously been demonstrated as an option for forming Earth’s Moon, for a limited range of tested parameters. Here we identify multiple regions of parameter space across which large immediate satellites can form (of order 1% the mass of the planet), for target planets ranging from 0.5 to 10 Earth masses, inclusive. We also confirm consistent results using the new SPH scheme REMIX, designed to improve the treatment of mixing and discontinuities in impact simulations. Furthermore, the rate of increase of the vapour mass-fraction with the system mass depends on the impact scenario, such that the post-impact disks of even the largest of these planets may not be fully vaporised.
Large moons may still be uncommon in general, but giant impacts offer a pathway for Super-Earths and even mini-Neptunes to gain fractionally massive satellites and the potential benefits of one for life.
How to cite: Kegerreis, J., Eke, V., Sandnes, T., and Davies, H.: A rapid route for even big planets to get big moons, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14985, https://doi.org/10.5194/egusphere-egu26-14985, 2026.
