Abstract The rim of the 0.9‐Ma‐old Zhamanshin impact crater in Kazakhstan is considered to be almost completely exposed via a series of hills surrounding a central flat area, indicating an apparent diameter of 14 km. This would make Zhamanshin the second largest impact crater of the Quaternary period. However, the overall geometry of these hills is not circular, and there is no visible central uplift, raising doubts about this diameter estimate. In this work, we used a set of geophysical methods (magnetic and gravity field mapping, and passive seismic measurements) to better characterize the geometry of the impact structure. The new potential field data reveal residual anomaly maps with significant concentric features extending only 2.5 to 3 km away from the structure center. The passive seismic data were used to derive H/V spectra. Combined with previous drilling information and surface geology, it allows us to delineate the depth of the interface between the fractured bedrock and the post‐impact sediments, which reveals a buried crater with a small central uplift. These new field geophysical data were combined with laboratory petrophysical measurements to constrain a model of the impact structure. The modeled complex impact structure has a 5 to 6 km diameter and is totally buried by sediments. This burial has occurred in <0.9 Ma, which is challenging but not incompatible considering the erosion rates in the area and the pre‐existing neighboring topography.

Abstract We present a comprehensive study of a meteorite collection from the Atacama Desert (Chile), the driest and most climatically stable desert in the world. This collection includes meteorites from three adjacent Dense Collection Areas (DCAs) in the northern part of the Atacama Desert: Calama, Sierra Gorda, and Chug Chug, referred to as the “Calama area.” Within this region (~550 km 2 ), we conducted a systematic search over a 2.5 km 2 zone in the Calama DCA and compared the resulting density to the nonsystematic recovery density in the Calama area. We also present the 36 Cl‐based terrestrial ages of 49 ordinary chondrites selected from the Calama area. The systematic search yielded a meteorite recovery density of 38 meteorites per km 2 (15 meteorites per km 2 for meteorites >20 g), and the collection exhibits a median terrestrial age of 303 ka. Notably, compared with the El Médano and Catalina DCAs, the Calama area is characterized by a lower meteorite density and younger meteorite terrestrial ages, most likely reflecting the region's more humid climate and more dynamic geomorphology due to its proximity to the pre‐Andean range. Our results further show that meteorite weathering is not correlated with terrestrial age but is instead essentially controlled by the initial porosity of the meteorite, itself related to shock stage. Nevertheless, the Calama area still exhibits higher densities and older terrestrial ages than any other hot desert in the world, confirming that the long‐term preservation of meteorites is observed across the entire Atacama Desert.

The Atacama Desert in Chile is characterized by its high meteorite density and old meteorite terrestrial ages. In this work, we present new terrestrial ages derived from measurements of the concentration of cosmogenic Cl-36 in the metal fraction of 51 ordinary chondrites collected over a 6.8 km(2) area located in the Catalina Dense Collection Area (Atacama Desert). Cosmic-ray exposure ages were also measured on a subset of the oldest meteorites to confirm that all but one had reached Cl-36 saturation before atmospheric entry. These meteorites have exceptionally old terrestrial ages, with an average of 937 ka (median 701 ka), making this collection the oldest known meteorite collection among hot deserts. This confirms that the Atacama Desert can preserve meteorites for long periods due to the prevailing stable hyper-arid climatic conditions. By combining terrestrial ages with pairing-corrected meteorite density estimates, we estimate the long-term meteorite flux to Earth over the past 2 Myr to be 74 +/- 9 meteorites >20 g per km(2) per Myr. This is consistent with estimates of (i) the modern flux, (ii) the integrated flux over the last similar to 100 kyr determined from Antarctic meteorites, and (iii) the average flux during the last similar to 50 kyr inferred from other hot desert collections. This suggests that the bulk meteorite flux to Earth has remained roughly stable over the past 2 Myr. We also investigate the compositional evolution of the flux by normalizing the H chondrite abundance to the total abundance of ordinary chondrites. Our results show a higher H chondrite abundance between 1200 and 400 ka, followed by a decline to present-day values. This temporal variation is not captured by the current dynamical models for meteoroid transfer to Earth, suggesting that short-term changes in the meteorite flux may be influenced by additional processes operating at a scale not considered by these models.

Meteoritical Bulletin 114 contains the 1944 meteorites approved by the Nomenclature Committee of the Meteoritical Society in 2025. It includes 15 observed falls, 1336 ordinary chondrites, 213 HED, 106 carbonaceous chondrites (including 8 ungrouped), 86 lunar meteorites, 39 ureilites, 28 iron meteorites (2 ungrouped), 24 martian meteorites, 24 pallasites, 21 primitive achondrites (3 ungrouped), 15 Rumuruti chondrites, 13 mesosiderites, 12 angrites, 10 enstatite chondrites, 9 ungrouped stony achondrites, and 8 enstatite achondrites (2 ungrouped). Of the meteorites approved in 2025, 1053 were collected in Africa, 479 in South America, 196 in Asia, 191 in Antarctica, 13 in North America, 9 in Europe, 2 in Oceania, and 1 from an unknown location.

CM chondrites are the archetypal group of aqueously altered meteorites, preserving records of water-rock interactions on planetesimals. Here, we couple rock magnetic properties with modal mineralogy measured from 48 CM chondrites to explore aqueous alteration through its influence on the magnetic mineralogy of these meteorites. These magnetic properties reflect a complex mixture of Fe-Ni metal, pyrrhotite, and magnetite in varying proportions and grain sizes. As the degree of alteration increases, the relative abundance of metal and pyrrhotite decreases with respect to magnetite, which forms predominantly as very fine grains (tens to hundreds of nanometers)—smaller, on average, than in CI1 chondrites. However, there is no trend between degree of alteration and magnetic properties, arguing that aqueous alteration may not be the only process that influenced the magnetic mineralogy of CM chondrites. Our measurements also indicate that transient heating events may have induced detectable changes in this mineralogy. We find hints of these changes throughout our datasets, possibly explaining the absence of simple trends with extent of aqueous alteration and arguing that weak/short-duration heating may be widespread among CM chondrites. If so, the magnetic mineralogy of many CM chondrites reflects a subtle interplay between aqueous alteration and weak transient heating.

Large terrestrial impacts may produce vast subsurface hydrothermal systems, capable of generating conditions favorable to the origin of life. Modeling suggests that these systems may persist for >1 million years for basin‐sized craters; however, direct experimental constraints on hydrothermal system duration are needed. Paleomagnetism may be used as a tool to study the nature and duration of the postimpact hydrothermal system generated within the upper peak ring of the 200 km diameter Chicxulub crater (Yucatán Peninsula, México). Previous work observed that upper peak ring suevite samples contained characteristic remanent magnetizations with negative and positive inclinations, with most samples having a magnetic inclination close to −44°, the expected paleoinclination at the crater at the time of the impact. This magnetic record was at the time interpreted as chemical remanent magnetization (CRM) acquired over a period of at least 150 thousand years, from the time of the impact in geomagnetic Chron C29r into Chron C29n. We conducted further paleomagnetic and rock magnetic studies of upper peak ring rocks and found that, while most samples likely contain CRM acquired during Chron C29r, the dispersion of magnetic inclinations within suevite subunits is more likely attributed to pre‐depositional remanence held within clasts than the recording of magnetic reversals. Therefore, the paleomagnetic record of the peak ring suevites is non‐ideal for inferring the duration of the Chicxulub postimpact hydrothermal system.

This study re-evaluates the anomalous subgroup of australites known as high Na/K (HNa/K) tektites (Chapman and Scheiber, 1969). Although previous compositional and isotopic analyses suggested a distinct origin, the group has never been formally recognized as a separate tektite strewn field. We present new data from six HNa/K tektites, complementing the eight specimens already described. We conducted a comprehensive investigation, including petrographic (optical and electron microscopy, and micro-X-ray tomography), geochemical (major and trace element compositions, Sr-Nd isotopic composition, 40Ar/39Ar dating), and spectroscopic (for the identification of inclusions) analyses. We concluded that the HNa/K tektites originated from a separate impact event compared to Australasian tektites; they have an andesitic to dacitic composition and arc-related trace element signatures. Lechatelierite (and phosphate) inclusions as well as high levels of chondritic contamination support an impact origin, for which we provide a more precise 40Ar/39Ar age: 10.76 +/- 0.05 Ma. For now, Sr-Nd isotopic data and trace elements composition point to three possible sources associated with active volcanic arcs: Luzon (Philippines), Sulawesi (Indonesia), and the Bismarck region (Papua New Guinea). Systematic petrographic and geochemical differences observed between tektites from the western and eastern parts of the -900-km-wide hypothesized strewn field (located in Southern Australia) may help to constrain the location of the source crater, but they need to be confirmed by the study of more specimens. We propose the name "Ananguite" for this new group of tektites.

A synthesis of more than 55 paleomagnetic studies yielding Tertiary primary or secondary magnetizations is used to evidence the rotations around a vertical axis since 40 Ma in the Western Alps and surrounding areas. In both external and internal zones of the orogenic prism, the rotations seem to be latitude dependent. In particular a widespread Eocene remagnetization of the Mesozoic European cover from Jura to Provence suggests possible effects of small local rotations of the External units of the belt. The most prominent feature is a consistent large (20–60 degrees) counterclockwise rotation observed in internal units and in the Northern Apennine areas. Also, the Corsica- North Sardinia block rotates similarly. Since the late Oligocene, apparent rotations around vertical axis are small North of the Po plain. It implies that the Torino-Monferrato North verging thrust plays a major role in accommodating the differential rotation. Therefore, domains separated from Europe by oceanic sutures (i.e. Liguria + Corsica − North Sardinia) can play as rigid bodies, while on the contrary, internal deformation deduced from paleomagnetic studies evidence that Apulia cannot be anymore regarded as a rigid body. In the Western Alps, the plate boundary, first localised at the ophiolite suture is then shifted along the Penninic Frontal Thrust. Tectonic models of the Alps that do not take into account the observed rotations have clearly to be reappraised.

Mitigation of the threat from airbursting asteroids requires an understanding of the potential risk they pose for the ground. How asteroids release their kinetic energy in the atmosphere is not well understood due to the rarity of large impacts. Here we present a comprehensive, space-to-laboratory characterization of an impact of an L chondrite, which represents a common type of Earth-impacting asteroid. Small asteroid 2023 CX1 was detected in space and predicted to impact over Normandy, France, on 13 February 2023. Observations from several independent sensors and reduction techniques revealed an unusual but potentially high-risk fragmentation behaviour. The nearly spherical 650 +/- 160 kg (72 +/- 6 cm diameter) asteroid catastrophically fragmented at a dynamic pressure of 4 MPa around 28 km altitude, releasing 98% of its total energy in a concentrated region of the atmosphere. The resulting shock wave was spherical, not cylindrical, and released more energy closer to the ground. This type of fragmentation increases the risk of substantial damage at ground level. These results warrant consideration for a planetary defence strategy for cases where a >3-4 MPa dynamic pressure is expected, including planning for evacuation of areas beneath anticipated disruption locations.

The Mw 7.0 Avezzano earthquake in the Abruzzo region of Italy claimed similar to 33,000 lives on January 13, 1915 making it one of the worst disasters in modern Italian history. The main rupture occurred along the Venere Fault, characterized by a polished, locally shiny, or powdery fault mirror showing extensive downdip striations, slickensides, and local reddish iron-oxide/hydroxide stains. The layer immediately below the mirror is a carbonate ultracataclasite that locally grades into an unconsolidated carbonate gouge. This type of carbonate fault mirror typically forms through two distinct synkinematic processes: i) intense frictional heating causing decarbonation, or ii) progressive grain-size reduction during slip at seismic velocities. In either case, friction drops substantially after initial displacement. The first process also results in intense fault pressurization followed by subsequent drastic drop in normal stress. Despite recent advances, the switch from high-friction/low slip velocity to low-friction/high slip velocity conditions in carbonate is still not fully understood. The Venere Fault, characterized by proven friction at seismic slip velocity, provides an ideal setting to investigate the nature and extent of dynamic weakening processes in carbonate faults. We use the high temperature sensitivity of iron oxide/hydroxide assemblages, and their magnetic remanence, to estimate frictional heat. Evidence for seismic slip in iron oxides and temperature uniformity along the fault surface have been tested through demagnetization experiments and 1D heat conduction modeling. Our data shows that the fault mirror underwent frictional heating during the 0.8 m slip event, but that this displacement was insufficient to reach pervasive decarbonation. We constrain the peak coseismic temperature along the fault plane to <400 degrees C through demagnetization experiments and 1D heat conduction modeling. Our results emphasize that coseismic deformation along natural faults is complex and therefore requires complementary field observations at multiple scales in order to encompass a broad range of faulting processes.

Serpentinization of ultramafic rocks is a key process in forming natural hydrogen. In deep settings, such as subduction zones, this process can be kinetically favored by high P-T conditions making the study of mantle rocks from these settings a compelling target for high-pressure sources of energy. Serpentinization of peridotites can lead to the formation of magnetite and it is commonly associated with a decrease in density and an increase in magnetization of the protolith rock. Gravity and magnetic methods can therefore be used to map and quantify the extent and degree of serpentinization. Here, we used a comprehensive dataset consisting of ground and Unmanned Aerial Vehicle (UAV) magnetic data, gravity data, and an extensive petrophysical data collection to explore the natural hydrogen potential in exhumed mantle rocks from the Monte Maggiore (MM) massif, in Corsica. The MM massif consists of a ∼4 km2 peridotite body, intruded by mafic pods and gabbroic dykes and surrounded by blueschist-facies continental units. It represents sub-continental mantle that underwent tectonic and magmatic evolution during the rifting stage of the Jurassic Ligurian Tethys oceanic basin and successive Alpine subduction to blueschist-facies conditions. On-going geochronological and geochemical investigations suggest that serpentinization occurred primarily in subduction making this area a suitable case study to investigate the formation of high-pressure sources of energy in such settings. We analyzed densities and magnetic properties of rocks from more than 100 sites across the massif and we used these data to identify domains exhibiting different degree of serpentinization and to model the current 3D structure of the massif using both forward and inverse modeling approaches. We estimated a minimum volume of the MM massif of 1.2 km3 and a vertical extent to a depth of 428 m below sea level. We used the modeled volumes and the amount of magnetite within each domain as a proxy for a conservative estimation of natural H2 production.

In this exciting new era of sample return space missions and improved detection of meteorite falls, the curation of pristine astromaterials has become a central concern. Well-preserved meteorites and returned extraterrestrial samples are absolutely unique sources of information regarding the formation and evolution of our solar system. Among their numerous informative properties, the paleomagnetic records of meteorites and returned samples (i.e., their natural remanent magnetization, NRM) provide invaluable insight on the physical characteristics of the first planetesimals, the Moon and Mars and on the environment in which these objects formed, as well as they long term evolution. Unfortunately, the NRM of a rock is probably one of the easiest and fastest property to alter, and today, very little action is taken in most curation facilities and collections to avoid magnetic contamination. In particular, contact with magnets and other unidentified, yet omnipresent, sources of magnetic fields are responsible for erasing the 4.5-billion-year old paleomagnetic records of >60

Meteoritical Bulletin 113 contains the 3646 meteorites approved by the Nomenclature Committee of the Meteoritical Society in 2024. It includes 17 falls, 2964 ordinary chondrites, 218 HED, 158 carbonaceous chondrites (including 7 ungrouped), 59 lunar meteorites, 38 iron meteorites (9 ungrouped), 30 ureilites, 31 primitive achondrites (3 ungrouped), 28 mesosiderites, 24 enstatite chondrites, 21 martian meteorites, 24 ungrouped stony achondrites, 20 Rumuruti chondrites, 17 pallasites, 8 angrites, 5 enstatite achondrites (one ungrouped), and 1 ungrouped chondrite. Of the meteorites approved in 2024, 1250 were collected in Antarctica, 1102 in Africa, 689 in Asia, 575 in South America, 17 in North America, 11 in Europe, and 2 in Oceania.

This study presents a refined approach to determine 14C saturation activities and C-14/Be-10 saturation activity ratios in chondritic meteorites with the goal to improve terrestrial age dating. By combining new model calculations for 10Be, C-14, and cosmogenic (Ne-22/Ne-21)cos, along with experimental data from 17 freshly fallen chondrites, we established reliable correlations for C-14 production rates and C-14/Be-10 production rate ratios as a function of (Ne-22/Ne-21)cos. The experimental data agree with the model calculations, and they fully confirm that C-14 production rates and C-14/Be-10 production rate ratios depend on shielding. Constrained correlations describe the experimental data for all shielding conditions and all ordinary chondrites mostly within the uncertainties given by the model. The new correlations therefore provide a significant improvement compared to the earlier approaches, in which average meteorite-type-dependent C-14 production rates and average C-14/Be-10 production rate ratios were assumed. Ignoring the shielding dependence introduces a size-dependent bias into the terrestrial age database. This study enables the determination of shielding-corrected C-14 saturation activities and C-14/Be-10 production rate ratios to calculate shielding-corrected terrestrial ages for meteorites reducing or eliminating a size bias in the database. In addition, this novel approach enables to give reliable uncertainty estimates of within 15% for the C-14 and C-14-10Be terrestrial ages.

During their stay at the surface of the Earth, meteorites undergo terrestrial weathering. In particular, the iron-nickel alloys and iron sulfides that are abundant in many types of meteorites transform into oxides and oxihydroxides (magnetite, maghemite, akaganeite, etc.). Mössbauer spectroscopy is a powerful tool to identify these weathering products. However, distinguishing signals from different phases summed up in the Fe3+ paramagnetic doublets in the central part of the spectrum remains challenging. This study focuses on a detailed investigation of meteorite weathering products to separate signals from different secondary minerals formed on Earth in a series of weathered meteorites. We carried out a room-temperature Mössbauer spectroscopy study on seventy ordinary chondrites collected in the Atacama Desert, Chile, in order to make a comparative qualitative analysis of the mineralogy of their terrestrial weathering products. Based on these results, three samples showing a variety of weathering products (Catalina 146, Catalina 535, and El Médano 070) were selected for a detailed study and two of them for low-temperature Mössbauer study. We found that, above 200 K, most meteorites exhibit superparamagnetic magnetization dynamics attributable to strong dispersed maghemite–magnetite phase formed as a weathering product. On the other hand, other iron-bearing weathering products (goethite, akaganeite, hematite) demonstrate line shapes of the corresponding partial components that are close to the shapes of the bulk samples. Only two of the 70 measured meteorites showed no superparamagnetic behavior at room temperature.

Strong magnetic fields have been measured from orbit around Mars over parts of the ancient southern highlands crust and on the surface at the InSight landing site. The geological processes that are responsible for generating strong magnetization within the crust remain poorly understood. One possibility is that intense aqueous alteration of crustal materials, through the process of serpentinization, could have produced magnetite that was magnetized in the presence of a global core-generated magnetic field. Here, we test this idea with geophysical and geochemical models. We first determine the magnetizations required to account for the observed magnetic field strengths and then estimate the amount of magnetite necessary to account for these magnetizations. For the strongest orbital magnetic field strengths, about 7 wt% magnetite is required if the magnetic layer is 10 km thick. For the surface field strength observed at the InSight landing site, 0.4-1.1 wt% magnetite is required if the magnetic layer corresponds to one or more of the three crustal layers observed in the InSight seismic data (with thicknesses from 8 to 39 km). We then investigate the minerals that are produced by aqueous alteration for various possible crustal compositions and water-to-rock ratios using a thermodynamic model. Magnetite abundances up to 6 wt% can be generated for dunitic compositions that could account for the strongest magnetic anomalies. For more representative basaltic starting compositions, however, more than 0.4 wt% can only be generated when using high water-to-rock ratios, which could account for the weaker magnetizations beneath the InSight landing site.

We present the outcome of search campaigns conducted in the Catalina Dense Collection area (DCA) located in the central depression of the Atacama Desert, Chile. The "Catalina Systematic Collection" (CSC) was assembled through systematic on-foot searches, resulting in a total of 1599 meteorites, before pairing, collected over a surface of 6.80 km(2). This yielded a recovery density of 235 meteorites per km(2) (67 meteorites >20 g per km(2)), making it the densest among hot deserts, even higher than the neighboring El M & eacute;dano DCA collection. This confirms that the central depression of the Atacama Desert holds the highest meteorite density among hot deserts. We classified 457 meteorites weighing more than 20 g. After correcting for various recovery biases, we estimated a true meteorite density on the ground of 131 meteorites per km(2) for meteorites >20 g before pairing. Using a probabilistic approach, we calculated an average pairing likelihood, yielding 71 meteorites >20 g per km(2) after pairing. This high density is likely linked to an old age of the CSC, which would also explain the absence of carbonaceous chondrites, as they are more prone to alteration by abrasion. This long meteorite accumulation period is related to the long-term hyper-aridity and surface stability of the Atacama Desert, which have persisted for several million years. Meteorites from the CSC show less chemical weathering on average than in other hot deserts, despite the long accumulation period. The H/L ratio in the CSC is higher than in meteorites from other hot deserts, Antarctica, and falls, but similar to the El M & eacute;dano collection, potentially reflecting variations in the composition of the meteorite flux over the past Myr.