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Two impact craters at Emmerting, Germany: field documentation and geophysics
Abstract
New research of two craters at Emmerting (No. 4 and No. 5), Germany, is presented. This paper should be the first part of two papers concerning presumed impact craters at Emmerting. The second paper will be about mineralogical/petrological, temperature and stress analyses. The enstatite-dominated meteoritic material, found in the crater No. 4 [Procházka et al., 2022; Procházka, 2023], is the subject of a separate detailed research. High-temperature effects and extreme deformation are significant in both craters. This deformation is explained with the effects of pressure wave(s) and later decompression in a target dominated by large but unconsolidated pebbles. Mutual collisions and secondary projectiles were documented. While most pebbles in the Crater No. 4 were thermally affected, the fine-grained fraction of the filling is poor in such material. It follows that small particles were volatilized and/or blown away during crater formation, or transported away later (e.g., by groundwater). Gamma-ray spectrometry has indicated that the walls of Crater No. 4 are significantly enriched in major natural radionuclides of Th, K and partly U, while the crater interior is depleted in these elements which are concentrated mainly in fine-grained fractions. This suggests a selective removal and volatilization of fine-grained material during the crater formation. The georadar measurements at both craters show that crater rims (walls) were partly pushed from below and partly heaped up from above with material that came from the crater interior. Georadar detected a compact body below the crater floor which is supported by results of resistivity measurements. A set of geophysical, geochemical, microscopic and mineralogical measurements proved that the craters at Emmerting are of impact origin. Extreme high temperature (HT) conditions inside the crater and small diameter of both craters indicate possible existence of very small meteoroids that are able to penetrate Earth´s atmosphere with high impact velocity (more than 30 km/s). This fact should challenge current models of bolide penetration through atmosphere.
... These sites include the Chrudim/Pardubice region in the Czech Republic [114] and a series of related strewn fields across the Czech territory [115]. In Germany, multiple impact sites have been documented: the Saarlouis structure with distinctive black glass melt rocks [116], the Chiemgau field showing evidence of a Holocene impact with archaeological connections [117][118][119], the Middle-Pleistocene Niederrhein deposit [120], the Holocene Franconia crater field [121], and the Pleistocene/Holocene Sachsendorf Bay structure [122]. Additionally, a 6400-yearold strewn field has been identified in Finland [123]. ...
We report diverse shock-metamorphosed and melted grains from the 1908 airburst site in Russia, one of history's most significant and enigmatic cosmic events. Analysis of samples from a rimmed crater-like feature near the epicenter using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), and cathodoluminescence (CL) revealed evidence of extreme conditions. Our findings indicate heterogeneous shock pressures (~≥2 GPa) and temperatures (~≥1710°C) produced various microparticles, including FeO and aluminosilicate glass microspherules, melted quartz microspherules, carbon spherules, glass-like carbon, and melted minerals. Notably, quartz grains exhibit high-temperature melting and shock metamorphism, including planar deformation features (PDFs) and planar fractures (PFs), with some showing glass-lined internal fractures and melted silica coatings. Similarly, some feldspar grains display melted feldspar coatings. While multiple origins for these materials are possible-including an older crater and volcanism-the evidence best supports the 1908 Tunguska airburst hypothesis. The abundance of melted, shocked materials in the biomass-burning layer aligns with proposals that airburst fragments struck the Earth's Airbursts and Cratering Impacts 2025 | Volume 3 | Pages: 1-26 | e-location ID: e20250001 G. Kletetschka et al.: New Evidence of High-Temperature, High-Pressure Processes 2 surface at velocities sufficient to produce shocked quartz. The coexistence of melted particles, shock-metamorphosed minerals, and unaltered grains suggests a heterogeneous energy distribution that created shallow craters and melted surface materials. These findings advance our understanding of airburst/impact mechanics, but few people have ever observed a dangerous airburst like Tunguska, so very little is known about them. Lacking sufficient real-world data, scientists should continue modeling these dangerous low-altitude airbursts to understand them better. The Tunguska event is a valuable case study demonstrating the urgent need to improve our planetary defense strategies.
The presentation deals mainly with melting and its relation to deformation phenomena in two craters at Emmerting, whose impact origin has been recently confirmed. See also abstract here: https://www.hou.usra.edu/meetings/lpsc2023/pdf/2102.pdf
Compared to intensive research on km‐sized meteorite impact craters, fewer studies focus on smaller craters. The small craters are often hard or impossible to recognize using “classical” criteria like the presence of shatter cones, shocked quartz, and geochemical indicators. Therefore, a long list of candidate structures awaiting approval/disapproval of their origin has been formed over the last decades. One of them is the Tor structure in central Sweden. To test a hypothesis of an impact origin of this structure, we have performed topographical analysis, geophysical studies, 10Be exposure dating of boulders, and 14C dating of Tor‐associated charcoal. None of the methods gave us a reason to claim the Tor structure is of impact origin. Thus, we support a recently suggested idea of Tor being formed by a grounded iceberg within a glacial lake.
Over the past few decades, it has become increasingly clear that the impact of interplanetary bodies on other planetary bodies is one of the most ubiquitous and important geological processes in the Solar System. This impact process has played a fundamental role throughout the history of the Earth and other planetary bodies, resulting in both destructive and beneficial effects. The impact cratering record of Earth is critical to our understanding of the processes, products, and effects of impact events. In this contribution, we provide an up-to-date review and synthesis of the impact cratering record on Earth. Following a brief history of the Impact Earth Database (available online at www.impactearth.com), the definition of the main categories of impact features listed in the database, and an overview of the impact cratering process, we review and summarize the required evidence to confirm impact events. Based on these definitions and criteria, we list 188 hypervelocity impact craters and 13 impact craters (i.e., impact sites lacking evidence for shock metamorphism). For each crater, we provide details on key attributes, such as location, date confirmed, erosional level, age, target properties, diameter, and an overview of the shock metamorphic effects and impactites that have been described in the literature. We also list a large number of impact deposits, which we have classified into four main categories: tektites, spherule layers, occurrences of other types of glass, and breccias. We discuss the challenges of recognizing and confirming impact events and highlight weaknesses, contradictions, and inconsistencies in the literature.
We then address the morphology and morphometry of hypervelocity impact craters. Based on the Impact Earth Database, it is apparent that the transition diameter from simple to complex craters for craters developed in sedimentary versus crystalline target rocks is less pronounced than previously reported, at approximately 3 km for both. Our analysis also yields an estimate for stratigraphic uplift of 0.0945D0.6862, which is lower than previous estimates. We ascribe this to more accurate diameter estimates plus the variable effects of erosion. It is also clear that central topographic peaks in terrestrial complex impact craters are, in general, more subdued than their lunar counterparts. Furthermore, a number of relatively well-preserved terrestrial complex impact structures lack central peaks entirely. The final section of this review provides an overview of impactites preserved in terrestrial hypervelocity impact craters. While approximately three quarters of hypervelocity impact craters on Earth preserve some portion of their crater-fill impactites, ejecta deposits are known from less than 10%. In summary, the Impact Earth Database provides an important new resource for researchers interested in impact craters and the impact cratering process and we welcome input from the community to ensure that the Impact Earth website (www.impactearth.com) is a living resource that is as accurate and as up-to-date, as possible.
A late Würmian and Holocene pollen profile from Tüttensee near Chiemsee, Bavaria, covering 14
millennia of vegetation history, shows the late Würmian reforestation of the area, Holocene woodland development,
and later the human impact on the landscape. In the early Holocene a distinct Ulmus phase preceded
the Corylus and Quercus expansion. Afterwards, between 6000 and 4000 BCE, Picea was most common. The
expansion of Fagus and Abies started at 4000 BCE, together with the decline of Ulmus . Fagus was more common
than Abies . From 500 BCE Abies started to decline, Fagus has also declined from 1000 CE onwards. Before the
modern times Picea / Pinus phase Quercus is prevailing. The prehistoric human impact is rather weak. A short
reforestation phase at ~ 1 BCE – 1 CE hints at the rather complex migration history in this region with so called
Celts, Germanic people and Romans involved. Strong human impact indicated by cereals, Plantago lanceolata ,
other human indicators and deforestation started at 900 CE.
We present evidence that in ~ 1650 BCE (~ 3600 years ago), a cosmic airburst destroyed Tall el-Hammam, a Middle-Bronze-Age city in the southern Jordan Valley northeast of the Dead Sea. The proposed airburst was larger than the 1908 explosion over Tunguska, Russia, where a ~ 50-m-wide bolide detonated with ~ 1000× more energy than the Hiroshima atomic bomb. A city-wide ~ 1.5-m-thick carbon-and-ash-rich destruction layer contains peak concentrations of shocked quartz (~ 5–10 GPa); melted pottery and mudbricks; diamond-like carbon; soot; Fe- and Si-rich spherules; CaCO3 spherules from melted plaster; and melted platinum, iridium, nickel, gold, silver, zircon, chromite, and quartz. Heating experiments indicate temperatures exceeded 2000 °C. Amid city-side devastation, the airburst demolished 12+ m of the 4-to-5-story palace complex and the massive 4-m-thick mudbrick rampart, while causing extreme disarticulation and skeletal fragmentation in nearby humans. An airburst-related influx of salt (~ 4 wt.%) produced hypersalinity, inhibited agriculture, and caused a ~ 300–600-year-long abandonment of ~ 120 regional settlements within a > 25-km radius. Tall el-Hammam may be the second oldest city/town destroyed by a cosmic airburst/impact, after Abu Hureyra, Syria, and possibly the earliest site with an oral tradition that was written down (Genesis). Tunguska-scale airbursts can devastate entire cities/regions and thus, pose a severe modern-day hazard.
Anhand von sedimentologischen und geländemorphologischen Untersuchungen wird die Abschmelzgeschichte des südöstlichen Chiemsee-Gletschers beschrieben. Mit dem Trockenfallen der Bad Adelholzen-Erlstätter Rinne im Verlaufe des Spätwürm entwickelt sich aus dem Abschmelzen des Eislappens in der Grabenstätter Bucht eine sich ständig tiefer legende konzentrische Abfolge von zunächst peripheren Entwässerungsrinnen, wobei die ältesten Rinnen dieser Phase bei Chieming, die jüngeren dann entsprechend weiter im Süden, in die zentripetale Richtung umschwenken. Die Entstehung des Tüttensee-Komplexes ist im Kontext dieser Entwicklung zu sehen. Er ist das Ergebnis der glazifluvialen und glazilakustrinen Sedimentation im Einflussbereich des sukzessiven Eisabbaus in der Grabenstätter Bucht in Kombination mit einer Toteisbildung im Bereich des heutigen Tüttensees. Dafür sprechen die stufenartige Abfolge der beschriebenen peripheren Abflussrinnen mit ihren immer tiefer liegenden Abflussniveaus, die Höhengleichheit von drei dieser Rinnen mit den Tüttensee-Terrassen sowie die für die jeweilige Terrassenentstehung typische glazifluviale bzw. delta-artige Sedimentstruktur und -reife. Dieses Ergebnis stellt ein Korrektiv zur Hypothese des Chiemgau-Impakts dar, wonach der Tüttensee ein Impaktkrater sein soll. Da diese nun falsifizierte Annahme vor allem im deutschsprachigen Raum von zahlreichen Medien propagiert wird, ist der folgende Artikel auf Deutsch verfasst, um einer breiten Leserschaft zugänglich zu sein.
At Abu Hureyra (AH), Syria, the 12,800-year-old Younger Dryas boundary layer (YDB) contains peak abundances in meltglass, nanodiamonds, microspherules, and charcoal. AH meltglass comprises 1.6 wt.% of bulk sediment, and crossed polarizers indicate that the meltglass is isotropic. High YDB concentrations of iridium, platinum, nickel, and cobalt suggest mixing of melted local sediment with small quantities of meteoritic material. Approximately 40% of AH glass display carbon-infused, siliceous plant imprints that laboratory experiments show formed at a minimum of 1200°–1300 °C; however, reflectance-inferred temperatures for the encapsulated carbon were lower by up to 1000 °C. Alternately, melted grains of quartz, chromferide, and magnetite in AH glass suggest exposure to minimum temperatures of 1720 °C ranging to >2200 °C. This argues against formation of AH meltglass in thatched hut fires at 1100°–1200 °C, and low values of remanent magnetism indicate the meltglass was not created by lightning. Low meltglass water content (0.02–0.05% H2O) is consistent with a formation process similar to that of tektites and inconsistent with volcanism and anthropogenesis. The wide range of evidence supports the hypothesis that a cosmic event occurred at Abu Hureyra ~12,800 years ago, coeval with impacts that deposited high-temperature meltglass, melted microspherules, and/or platinum at other YDB sites on four continents.
The disastrous Tunguska explosion (TE) in 1908 uprooted trees in a radial pattern. Several trees in this area survived and kept growing in the post-Tunguska environment. We collected samples from surviving trees (14 and 131 years old at the time of the TE) that lived until collection in 2008 and another sample from a control tree farther from the blast epicenter (germination in 1928), which were analyzed by x-ray fluorescence (XRF) and prompt gamma neutron activation analysis. Chemical composition of xylem tracheids of the surviving trees revealed several patterns potentially related to the TE. A calcium peak is associated with the 1908 ring in both of the exposed trees, but additional high concentrations in adjacent rings could represent enhanced translocation of Ca over the whole sapwood as a response to defoliation from the TE. Sr and Mn anomalies near 1908 appeared in one exposed tree but not in the other. High-resolution XRF indicates Ca as well as Zn anomalies are primarily located in the earlywood of the rings, whereas peaks in Mn, Zn and Cu are more associated with the latewood. A directional response was evidenced by a wider zone of elevated Ca in the rings on the southern side toward the airblast, which might have experienced the greatest defoliation and perhaps enhanced root damage as the tree was rocked by the pressure wave. The TE event in the middle of the 1908 growing season must have triggered tree responses to deliver more nutritive resources to the crown in order to hasten restoring new leaves in the crown and to aid in structural repair.
For several known and a few newly proposed meteorite craters in the Chiemgau meteorite impact strewn field the LiDAR data of the Digital Terrain Model DTM have been processed to reveal various maps and cross sections based on a high-resolution mesh down to 1 m and contour interval down to 0.2 m. The data processing highlights particular crater features that remain hidden in fieldwork and on conventional topographic maps and even may debunk mistaken structures.
The Chelyabinsk meteorite fragment that landed in the Chebarkul lake in Russia on 15 February 15 2013 weighed over half a ton. We provide magnetic field maps that were obtained during underwater measurements above the fragment. The data acquisition process was multiple GPS referenced magnetic surveys 0.5 m – 1 m above the top of the lake sediment layer at 10 m water depth. Gradiometric configuration of the survey using two tri-axial fluxgate magnetometers helped to suppress local geological anomalies. The location of the ice crater and the underwater magnetic anomaly provided final meteorite landing coordinates, which were made available during meteorite recovery.
Arguing from a critical reading of the text, and scientific evidence on the ground, the authors show that the myth of Phaethon – the delinquent celestial charioteer – remembers the impact of a massive meteorite that hit the Chiemgau region in Bavaria between 2000 and 428 BC.
The Chiemgau strewn field in the Alpine Foreland discovered in the early new millennium comprises more than 80 mostly rimmed craters in a roughly elliptically shaped area with axes of about 60 km and 30 km. The crater diameters range between a few meters and a few hundred meters. Geologically, the craters occur in Pleistocene moraine and fluvio-glacial sediments. The craters and surrounding areas so far investigated in more detail are featuring heavy deformations of the Quaternary cobbles and boulders, abundant fused rock material (impact melt rocks and various glasses), shock-metamorphic effects, and geophysical anomalies. The impact is substantiated by the abundant occurrence of metallic, glass and carbon spherules, accretionary lapilli, and of strange matter in the form of iron silicides like gupeiite and xifengite, and various carbides like, e.g., moissanite SiC. The hitherto established largest crater of the strewn field is Lake Tüttensee exhibiting an 8 m-height rim wall, a rim-to-rim diameter of about 600 m, a depth of roughly 30 m and an extensive ejecta blanket. Physical and archeological dating confine the impact event to have happened most probably between 1300 and 300 B.C. The impactor is suggested to have been a low-density disintegrated, loosely bound asteroid or a disintegrated comet in order to account for the extensive strewn field.
Abstract— Numerous circular depressions north of Burghausen in eastern Bavaria, with diameters ranging from meters to tens of meters in size and dispersed over an area of at least 11 times 7 km, are suspected to have an extraterrestrial origin since they resemble other small meteorite impact craters. The depressions are bowl‐shaped, have high circularity and a characteristic rim. Most of them were formed in unconsolidated glacial gravels and pebbles intermixed with fine‐grained sand and clay. Magnetic investigations reveal weak anomalies with amplitudes of less than ±10 nano Tesla (nT). In some cases, the origins of the anomalies are suspected to be due to human activity within the structures. So far, no traces of meteoritic material have been detected. An evident archaeological or local geological explanation for the origin of the craters does not exist. A World War I and II explosive origin can be excluded since trees with ages exceeding 100 years can be found in some craters. One crater was described in 1909. Carbon‐14 dating of charcoal found in one crater yielded an age of 1790 ± 60 years. Hence, a formation by meteorite impacts that occurred in Celtic or early medieval times should be considered. A systematic archaeological excavation of some structures and an intensified search for traces of meteoritic material are planned.
The Bajada del Diablo astrobleme-strewn field is a huge domain of enigmatic circular structures located in central Patagonia.Three more localities are herein described, adding to the first area studied so far. Taking into consideration the four areas, a single, blurred crater dispersion ellipse has been identified. The four sectors now have been investigated, mapped, and georreferenced. Their circular structures, with a total of 185 (some of which are partially obliterated by erosion or sediment accumulation), were identified by remote sensing techniques, but many have been evaluated in situ and interpreted as impact craters. Moreover, two of the structures have been surveyed in detail in the field using a total station instrument.In addition to the previously known occurrence of circular structures on the Eruptive Complex Quiñelaf (Miocene basalts), the Pampa Sastre Fm. (Pliocene conglomerates), and of the Pleistocene pediment gravels and sands, and the geomorphological inferences that have suggested the extra-terrestrial origin of this event, we should now add that the recurrent absence of the cited Pliocene stratigraphic unit at the bottom of the craters is found in the pediment gravel and sands. Its removal has been interpreted as directly related to the impact, according to the magnetometric record of existing magnetic anomalies.Other preliminary observations on the collected samples (glass, breccias, and, most relevant, Fe-Ni-bearing spherules picked up within the impact zones) are herein discussed.Two hypotheses have been put forward about the nature of the possible impacting object that formed these astroblemes which, fragmented into hundreds of pieces, hit the surface of the Earth most likely in middle Pleistocene times. One of these hypotheses is related to the impact of a disintegrated asteroid of the rubble pile type, whereas a second hypothesis refers to the collision of a split comet with the Earth surface. The latter hypothesis is favoured since no meteorite fragments have been found so far.
Abstract— On September 15, 2007, a bright fireball was observed and a big explosion was heard by many inhabitants near the southern shore of Lake Titicaca. In the community of Carancas (Peru), a 13.5 m crater and several fragments of a stony meteorite were found close to the site of the impact. The Carancas event is the first impact crater whose formation was directly observed by several witnesses as well as the first unambiguous seismic recording of a crater-forming meteorite impact on Earth. We present several lines of evidence that suggest that the Carancas crater was a hypervelocity impact. An event like this should have not occurred according to the accepted picture of stony meteoroids ablating in the Earth's atmosphere, therefore it challenges our present models of entry dynamics. We discuss alternatives to explain this particular event. This emphasizes the weakness in the pervasive use of “average” parameters (such as tensile strength, fragmentation behavior and ablation behavior) in current modeling efforts. This underscores the need to examine a full range of possible values for these parameters when drawing general conclusions from models about impact processes.
Shock metamorphism of Coconino sandstone at Meteor Crater /Arizona/, examining porosity role in rock compression and in high pressure phases formation
Abstract— Detailed analysis of the fragmentation of the Morávka meteoroid during the atmospheric entry is presented. The analysis is based on the measurement of trajectories and decelerations of fragments seen in a video and at the locations of energetic fragmentation events from seismic data obtained at several stations in the vicinity of the fireball trajectory. About 100 individual fragments are seen on video frames. Significant deceleration of the fireball at heights of ˜45 km revealed that the meteoroid had already fragmented into ˜10 pieces with masses of 100–200 kg, though the fireball still appeared as a single object. At heights of 37–29 km, all primary fragments broke-up again under dynamic pressures up to 5 MPa. The cascade fragmentation then continued, even though smaller pieces breaking off from the larger masses were increasingly decelerated and the dynamic pressure acting upon them decreased. At each fragmentation, a significant part of the mass was lost in the form of dust or tiny particles. This was the dominant process of mass loss. The continuous ablation due to melting and evaporation of the meteoroid surface was less efficient with a corresponding ablation coefficient of only 0.003 s2 km-2. During fragmentation, some pieces achieved lateral velocities up to 300 m/s, about an order of magnitude more than can be explained by aerodynamic loading. The fragmentation continued even after ablation ceased, as demonstrated by the incomplete fusion crust covering all recovered fragments. We estimate that several hundreds of meteorites of a total mass of ˜100 kg landed, mostly in a mountainous area not suitable for systematic meteorite searches. Six meteorites with a total mass of 1.4 kg were recovered up to the end of May 2003. Their positions are consistent with the calculated strewn field.
Geologicky mladé "zamrzlé" tavení hornin na několika lokalitách v Bavorsku: neobvyklý typ impaktu a výbuchy ve vzduchu? (Geologically young "frozen" melting of rocks at several sites in Bavaria: an unusual type of impact and explosions in the air?)
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na několika lokalitách v Bavorsku: neobvyklý typ
impaktu a výbuchy ve vzduchu? (Geologically
young "frozen" melting of rocks at several sites in
Bavaria: an unusual type of impact and explosions
in the air?). Proc. 26 th Quaternary Seminary
Meeting, Brno, Czech Republic.
Der Tüttensee im Chiemgau-Toteiskessel statt Impaktkrater
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