Meteorite craters: impact approachable

Already in the early days of the exploration of the Chiemgau impact crater strewn field at the beginning of the new millennium, a perfectly semicircular structure was discovered during a flight, which seemed to be punctured into the bank of the Inn river near Marktl. Geological research on the ground and sampling quickly proved the impact nature of this well 50 m measuring crater, which was introduced as No. 24 into the crater list of the Chiemgau impact, which had been meticulously conducted by local history researchers. The semicircular structure was easily explained by the erosion of floods in the valley of the Inn river

Not recorded in the topographical maps and soon blocked with a large stable it fell into oblivion and was only recently opened to the eye in full splendor by the Digital Terrain Model DGM 1 (Fig. 1).

Bildschirmfoto 2017-08-14 um 18.56.49

Fig. 1. Aiching semi crater in the Inn river bank vis-à-vis the town of Marktl (UTM coordinates 338863, 5346952). Digital Terrain Model. Continue reading

The Chiemgau meteorite impact at the Lunar and Planetary Science Conference (LPSC) 2017: new contributions (abstract articles)

At the this year’s prestigious meeting of  the Lunar and Planetary Institute in The Woodlands, Texas, the following abstract articles that relate to the Chiemgau meteorite impact have been published:

Molnár M. Ventura K. Švanda P. Štaffen Z. Rappenglück M. A., Ernstson, K.:

Chrudim – Pardubice: Evidence for a Young Meteorite Impact Strewn Field in the Czech Republic –  Widespread finds of rocks and glasses with shock metamorphism and typical of meteorite impact suggest a Holocene impact event in the Czech Republic.

The article reports on a newfound very young meteorite impact event in the Czech Republic amazingly similar to the Chiemgau and Saarland (Nalbach) impact events in Germany. A possibly simultaneous impact having affected Central Europe over a distance of more than 650 km is discussed. Click the abstract article!

Procházka V. Trojek T.
XRF- and EMP- Investigation of Glass Coatings and Melted Domains of Pebbles from Craters in Chiemgau, Germany
Shock-induced melting mainly of biotite (?) produced typically porous veinlets. External glass coatings are rich in K and Cu (from plant biomass?), rarely in Ni.

The Czech authors report on investigations of shocked cobbles excavated from the Kaltenbach and #004 impact craters belonging to the Chiemgau meteorite impact strewn field. Click the abstract article!

 

New article: The Digital Terrain Model (DTM) and the craters of the Chiemgau meteorite impact strewn field

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The Digital Terrain Model (DTM) and the evaluation of known and the search for new craters in the Chiemgau meteorite impact strewn field [PDF DOWNLOAD]

Kord Ernstson* (2017)

Abstract. – 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.

********************************************************************************************************* *Faculty of Philosophy I, University of Würzburg, Germany, kernstson@ernstson.de

Content 1 Introduction – 2 The Chiemgau meteorite impact event 3 Data processing 3.1 Terrain imagery 3.2 Horizontal gradient 3.3 Data filtering 3.4 Cross sections 4 Examples 4.1 Small craters in the DTM 4.2 Peripheral depressions around small craters 4.3 Medium-sized craters in the DTM 4.4 Mistaken structures 5 A possible large-sized crater in the DTM 6 Discussion and conclusions 7 References Appendix

The Chiemgau impact at the LPSC 2016

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At the this year’s internationally prestigious Lunar and Planetary Science Conference in the Woodlands, Texas, two contributions on the Chiemgau meteorite impact crater strewn field in Germany have been presented (after preceding LPSC contributions in the years 2011, 2012 and 2014).

Our Czech colleagues presented their results on rock magnetic properties of shocked rocks from smaller craters in the strewn field (click to download the full abstract article):

Evidence for superparamagnetic nanoparticles in limestones from Chiemgau crater field, SE Germany. V. Procházka1 , G. Kletetschka1 , 1 Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Charles Univ., Albertov 6, CZ-12843 Praha 2, Czech Republic (vprochaska@seznam.cz)

and the Chiemgau Impact Research Team (CIRT) reported on the meteorite impact-induced Lake Chiemsee tsunami (click to download the full abstract article):

EVIDENCE OF A METEORITE IMPACT-INDUCED TSUNAMI IN LAKE CHIEMSEE (SOUTHEAST GERMANY) STRENGTHENED. K. Ernstson, Faculty of Philosophy I, University of Würzburg, D-97074 Würzburg, Germany, kernstson@ernstson.de

T. Shumilova, S.N. Tkachev, S. Isaenko, S. Shevchuk, M.A. Rappenglück & V.A. Kazakov: new article in the journal CARBON

Only recently an article has been published in the reputable journal Carbon with our colleague Dr. Tatyana Shumilova, Russian Academy of Sciences, as first author and Dr. M.A, Rappenglück from our CIRT research group as one of the co-authors:

T. Shumilova, S.N. Tkachev, S. Isaenko, S. Shevchuk, M.A. Rappenglück & V.A. Kazakov (2016): A “diamond-like star” in the lab. Diamond-like glass. – Carbon 100(100):703-709. Continue reading

A cross-bedded diamictite: evidence of a big Lake Chiemsee tsunami in the Chiemgau meteorite impact event strengthened

A cross-bedded diamictite: evidence of a big Lake Chiemsee tsunami in the Chiemgau meteorite impact event strengthened

Kord Ernstson*

Abstract. – Gravel exploitation near Lake Chiemsee has exposed a quarry face exhibiting a larger diamictite deposit with significant cross bedding. The grain size of the material varies between silt and sharp-edged blocks up to the size of 1 m. In the majority, even the smaller fraction of limestone particles does not show any roundness. Frequently, limestone cobbles are covered with multiple sets of scratches and polish. For the cross-bedded diamictite exposed at the edge of a flat chain of hills a glacial deposit, e.g., as an end moraine, can be excluded. The multiple, small-scale cross-bedding units as well as the transport over short distance point to a close-by, short-term process of formation. It is interpreted as the result of a big Lake Chiemsee tsunami that was triggered in the Holocene Chiemgau impact event. The deposit also raises issues relevant to a Lake Chiemsee glacier.

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* Faculty of Philosophy I, University of Würzburg, Germany; kernstson@ernstson.de

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Continue reading

The Nalbach (Saarland, Germany) impact at the LPSC 2015

At the this year’s Lunar and Planetary Science Conference in the Woodlands, Texas, the abstract article entitled “Strong shock metamorphism and a crater: evidence of a Holocene meteorite impact event near Nalbach (Saarland, Germany)” by Nico Berger, Werner Müller and Kord Ernstson was presented. Here, we in particular point out that the peculiar findings in the Nalbach area are revealing remarkable similarities to impact features in the Holocene large Chiemgau impact strewn field in southeast Germany, and meanwhile the possibility that the Nalbach impact is a companion to the Chiemgau impact is seriously being discussed. Click on the image to open the full text!

LPSC 2015 abstract Nalbach impact

Chiemgau impact – new contribution: compilation of mineralogical evidence in the meteorite crater strewn field

iron silicides Chiemgau impact meteorite crater strewn field   Under the scanning electron microscope (SEM): The odd world of the iron silicides from the Chiemgau impact meteorite crater strewn field (click to enlarge). Contribution to the mineralogy meeting of the Russian Academy of Sciences in Syktyvkar:

Meteorite impact on a micrometer scale: iron silicide, carbide and CAI minerals from the Chiemgau impact event (Germany)

 Michael A. Rappenglück1, Frank Bauer2, Kord Ernstson3, Michael Hiltl4

1 Institute for Interdisciplinary Studies, Gilching, Germany; mr@infis.org – 2 Oxford Instruments GmbH NanoScience, Wiesbaden, Germany; Frank.bauer@oxinst.com – 3Faculty of Philosophy I, University of Würzburg, Germany; kernstson@ernstson.de – 4 Carl Zeiss Microscopy GmbH, Oberkochen, Germany; mhiltl@online.de 

Shortly after the meeting between the 19th and 22nd May in Syktyvkar the Proceedings volume has been published:

Proceedings Yushkin Memorial Meeting Syktyvkar

Problems and perspectives of modern mineralogy (Yushkin Memorial Seminar–2014) Proceedings of mineralogical seminar with international participation Syktyvkar, Komi Republic, Russia 19–22 May 2014

 

The Rappenglück et al. contribution condenses the mineralogical evidence of the iron silicides from the Chiemgau impact crater strewn field that has been compiled with invaluable support by Carl Zeiss Microscopy und Oxford Instruments NanoScience.

We remind of the fact that in the beginning of the research on the Chiemgau impact the group of quite experienced local historians and amateur archeologists had detected the metallic iron silicides and, after having been aware of their relation to crateriform structures, had published the possible meteoritic origin of the matter. Investigations and attempts, respectively, to dismiss all iron silicides as industrial waste product, or at least as terrestrial, followed, and they are still spread rumors as for instance by the Bavarian Geological Survey (Landesamt für Umwelt, LfU) which is commented (in German) elsewhere and may be clicked HERE.

Ultimately it is evident that these local historians who later got together with scientists from geosciences, astronomy, archeology and historical scholarship to establish the Chiemgau Impact Research Team (CIRT), are proved right!

The abstract article from the Proceedings volume may be clicked HERE. The corresponding, much more informative POSTER may be clicked also for download. PLEASE NOTE: Depending on the selected browser the screen quality may appear quite different. As the case may be we suggest to save the file on the computer and to activate it with a pdf reading program. WARNING: The poster pdf has a size of more than 50 megabyte.

 

Microtektites from the Chiemgau impact fallout

Tektites are well-known gravel-size natural glasses that according to current knowledge form in the very early process of impact cratering by melting and/or vaporizing of superficial soil and rocks ejected as melt or vapor from the impact crater. On reentry in the atmosphere and cooling, the glass bodies exhibiting characteristic shapes fall to Earth where they form part of the impact ejecta. By definition tektites that are smaller than 1 mm are called microtektites. Although the origin of tektites from impact events is generally accepted the exact mode of formation is not well understood.

In the Chiemgau meteorite crater strewn field impact glasses are found widespread in various formations, and tektite-like bodies of a dense black glass with vesicles have attracted considerable attention (Fig. 1).

tektite-like glass, Chiemgau-impact, similar to irghizites

Fig. 1. Dense black glass particles from the Chiemgau impact strewn field frequently exhibiting tektite-like shape and twisted form similar to irghizites from the Zhamanshin impact crater. These are NOT the Chiemgau microtektites! – Click to enlarge.

Outside the crater strewn field in the foothills of the Alps at some 1500 m altitude (Fig. 2) a systematic search for impact fallout has revealed not only abundant tiny iron silicide particles (e.g., minerals xifengite and gupeiite) but also microtektites widely distributed in the soils (Fig. 3).

Fig. 2. Location map for the Chiemgau impact meteorite crater strewn field and the sites of the microtektite finds. Google maps. – Click to enlarge.

They show the very typical splash shapes like spheres, teardrops and irregular dumbbells (Fig. 3). They are fully transparent and have a mostly yellowish-brownish-grayish color. Bubble inclusions are frequent.

microtektites from the Chiemgau impact strewn field Fig. 3. Typically shaped microtektites from the soil in the foothills of the Alps near the Chiemgau impact crater strewn field. Optical microscope images, 100 µm scale bar in each case.

The SEM micrographs in Fig. 4 especially point to the in part very strange surface features and bizarre forms exhibiting micrometer-sized glass filaments and twisted bodies.

Chiengau impact microtektites SEM

Fig. 4. SEM images of microtektite-like glass particles.
Note the tiny, micrometer-sized glass filaments (lower
right) of the particle over it.

Relations

Microtektites are known, e.g., from the North American strewn field (cores from the Deep Sea Drilling Project), from the Australasian tektite strewn field, from the Ivory Coast strewn field and seem to be associated with the Chicxulub KT impact and Late Eocene impacts. A problem with proposed microtektite occurrences may arise from a possible confusion with spherules of an origin other than from impact vapor/melt solidification especially when a direct relation with an impact site is lacking. Even volcanic spherules may show dumbbell and teardrop shapes, while industrially produced microscopic glass spheres (e.g. from fly ash) have in general no teardrop or dumbbell counterparts.  A comprehensive consideration of the various possibilities including volcanic, man-made and even organic matter is given by Glass & Simonson (2013).

In the case of the Chiemgau impact microtektites a confusion with volcanic or man-made glass particles can be excluded with a high degree of probability since the very nearby really existing impact site and the exceptionally typical shape of known microtektites provide the simplest explanation for their origin. Nevertheless, a thorough analysis of their composition and a highly magnifying SEM imagery of their surfaces are in progress. Perhaps, some more insight into the general process of microtektite formation – in this case possibly as an impact vapor plume condensate – can be attained.

Reference

Glass, B. P. and Simonson, B.M. (2013): Distal Impact Ejecta Layers: A Record of Large Impacts in Sedimentary Deposits. – Impact Studies, 400 p., Springer.