Impact spallation – completely underestimated by impact researchers.

Left, from the top down: Shock spallation experiment producing typical open tensile fractures. – Spallation fractures in shocked quartzite cobble, Azuara/Rubielos de la Cérida impact event (Spain). Microscopic shock spallation in sandstone quartz grains, Rubielos de la Cérida impact basin. – To the right: Local megascopic impact spallation in well-bedded Jurassic limestones; Azuara (Spain) impact structure northern rim region south of Fuendetodos. Link to a full article on impact spallation.

Enigmatic Impact Breccias Probably Linked to the Ries Crater (Germany) Impact Event -Alemonites from Bavaria and sunstones from the Czech Republic

Alemonite (DE) and sunstone (CZ) samples from the field 

Shock effects in alemonites and sunstones

Lunar & Planetary Science Conference (LPSC ) 2019 : Click Abstract and Poster!

Trigonal and cubic Fe2Si polymorphs (hapkeite) in the eight kilograms find of natural iron silicide – a probably new class of meteorites

Excavated from the Chiemgau impact crater strewn field: 8 kg (eight – no printer’s error) iron silicide chunk.

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Impact sulfate melt rock from the Rubielos de la Cérida  impact basin (Azuara impact event, Spain) – a rare meteorite impact signature

Strongly shocked quartzite clasts in the low-density, highly porous CaSO4 matrix.

Clast of sulfate melt rock in the Barrachina megabreccia -The sulfate melt rock under the SEM. Note the vesicular texture. – More about Azuara and Rubielos de la Cérida impact melt rocks (carbonate melt, carbonate-phosphate melt, silicate melt, carbonate-psilomelan melt).

Polymictic impact breccia dike sharply cutting through well-bedded Muschelkalk limestone. – Rubielos de la Cérida impact basin (Spain) near Olalla.

Very nice example of the many breccia dikes in the Spanish Azuara impact structure and the Rubielos de la Cérida impact basin (crater chain). – More about impressive breccia dikes (dike breccias) in the Rubielos de la Cérida basin and the Azuara structure.

Impact breccia in lapillistone matrix. – Rubielos de la Cérida impact basin (Spain) near Olalla.

Muschelkalk breccia-within-breccia, lapillistone matrix (accretionary lapilli).

Ground Penetrating Radar (GPR): Emmerting #004 crater, Chiemgau meteorite impact strewn field (Bavaria, Southeast Germany)

Ground Penetrating Radar (GPR) – meteorite crater Chiemgau impact

Diametral radargram across one of the most spectacular craters in the Chiemgau meteorite impact strewn field. Loamy-gravelly target material. Impact melt rocks, strong shock metamorphism. Strong reflectivities down to several meters depth are explained by extreme high-temperature sintering of the underground material. Note the complex excavation with the ring wall wandering outwards (as indicated with “real reflections”). 25 MHz center frequency with modulated 200 MHz.

More about GPR measurements over young meteorite craters: Click HERE

Chiemite – carbon impact rock (impactite) – the Chiemgau impact event as namesake

REM image. – Formation in spontaneous shock carbonization of the vegetation in the impact area. Investigations at the Diamond Laboratory, Geological Institute, Russian Academy of Science Syktyvkar, with optical and atomic force microscopy (AFM), X-ray fluorescence spectroscopy (RFA), scanning electron (SEM) and transmission electron (TEM) microscopy, high-resolution Raman spectroscopy, X-ray diffraction (XRD) and differential thermal analysis (DTA) as well as δ13C and 14C radiocarbon isotope data analysis.

Approx. 95% carbon; detection of diamond and carbyne; formation conditions for the latter 2500 – 4000°C and some GPa pressure.

Very “smart” people are still of the opinion that it is coke. Take a look at that too: file: EGU 2019 chiemite poster.pdf – Wikipedia

SEM detail view of the chiemite.

An extensive article on the chiemite has recently been published in print:

Enigmatic Glass‐Like Carbon from the Alpine Foreland, Southeast Germany: A Natural Carbonization Process.

Impact shock feature: ballen structures from four new impact sites in Central Europe (Germany, Czech Republic)

Ballen structures in silica form a characteristic texture in quartz that in general is considered a result from various stages of phase transformation and recrystallization of amorphous silica like e.g., diaplectic glass and hence are regarded as shock indicator. A different model has recently been suggested that proposes a formation of ballen in quartz in an extreme thermal shock event.

Ballen structures (photomicrographs, plane light and crossed polarizers; field width 560 µm). – Saarland (Nalbach, Saarlouis) impact.

Ballen structures impact merging into tridymite and cristobalite.(photomicrographs, crossed polarizers and plane light; field width 1.4 mm). – Saarland (Nalbach, Saarlouis) impact.

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Ballen structures (plane light and crossed polarizers), Chiemgau impact meteorite crater strewn field; Stöttham archeological excavation, catastrophe layer.       Click the LPSC poster!

Ballen structures; Chrudim – Pardubice impact site (Czech Republic); asphaltic polymict impact breccia.

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Ballen structures (photomicrograph, plane light); granitic impact melt rock sheet, Bach/Regensburg (Germany) impact site.

Comment on: ” Schmieder, M. and Kring, D. A. (2020) Earth’s Impact Events Through Geologic Time: A List of Recommended Ages for Terrestrial Impact Structures and Deposits. – Astrobiology, 20, 91-141.”

by Kord Ernstson¹ & Ferran Claudin² (Jan. 2021)

Abstract: We use Schmieder and Kring’s article to show how science still works within the so-called “impact community” and how scientific data are manipulated and “rubber-stamped” by reviewers (here, e.g., C. Koeberl and G. Osinski). We accuse the authors of continuing to list the Azuara and Rubielos de la Cérida impact structures and one of the world’s most prominent ejecta occurrences of the Pelarda Fm. in Spain as non-existent in the compilation. The same applies to the spectacular Chiemgau impact in Germany, which has been proven by all impact criteria for several years. For the authors’ dating list, we propose that the multiple impact of Azuara is included together with the crater chain of the Rubielos de la Cérida impact basin as a dated candidate for the third, so far undated impact markers in the Massignano outcrop in Italy.

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1 University of Würzburg, 97074 Würzburg (Germany); kernstson@ernstson.de. 2 Associate Geological Museum Barcelona (Spain); fclaudin@xtec.cat

A PDF of the complete article may be downloaded here.

Continue reading ““Earth’s Impact Events Through Geologic Times”: Comment on Schmieder & Kring article in Astrobiology”