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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Chiemgau impact: taking a look at Russia

The Tschebarkul 2013 super bolide, Tscheljabinsk, Russia – what do we currently know? 

Explosion and impact of the meteor: In the meantime the commotion has died down and has given way to more factual information and scientific relevance, and here on our website we would like to dedicate sufficient coverage of the current knowledge.

Such an event that we have now witnessed in Russia undoubtedly highlights also the Chiemgau impact and the related discussions about the impact parameters like the kind of impactor, fragmentation in the atmosphere and the dimensions of the strewn field.

 Source: Svetlana Korzhava; WIKIMEDIA COMMONS

Important information is coming directly from Russia where as is well known good scientific relations of the CIRT exist, and we thank particularly Dr. Slava Gusiakov from the Holocene Impact Working Group for his personal communication.

Our article:  Continue reading

Chiemgau impact: the dual crater at the bottom of Lake Chiemsee – nice counterparts

Since a few years there is evidence of a dual meteorite crater at the bottom of Lake Chiemsee (Fig. 4) in the Chiemgau meteorite crater strewn field. The search for a suspected impact into the lake was originally based on reports of fishermen about unusual sharp-edged large stones at the lake bottom that had damaged their fishnets. Such stones are in fact foreign matter in the lake. A general echo sounder campaign, followed by a detailed survey veritably revealed a peculiar structure, likewise a foreign element in the lake, with all evidence of a rimmed doublet crater (Fig.1).

doublet meteorite crater at the bottom of Lake Chiemsee, Chiemgau impact strewn fieldFig. 1. The proposed meteorite doublet crater at the bottom of Lake Chiemsee from detailed sonar echo sounder measurements. Meter scale indicates water depth.

The similarity to meteoritic dual craters on Mars is striking (Fig. 2). From the Mars image it is evident that the doublet structure formed on synchronous impact of twin projectiles. Continue reading

Chiemgau impact: conducting hypervelocity impact experiments

Experimental hypervelocity impact crater generation and the formation of the Lake Tüttensee crater

hypervelocity impact crater experiments in flour

Fig. 1. Snapshot of a hypervelocity impact into flour taken from a high-speed camera video. The full video may be played back by clicking on the image.

Meteorite impact is a fascinating geologic process that for many geologists, however, has remained enigmatic. Therefore we are glad to present here on our website some results of experimental impacts that have been recorded by high speed cameras. This has been possible by a cooperation between the CIRT and Werner Mehl who is a world-wide known specialist for ballistics and high speed photography http://www.kurzzeit.com/eng/startseite.htm).

experimental hypervelocity impact into flor
Fig. 2. Experimental hypervelocity impact crater produced by a projectile (as lying in the hand) in a target of flour. The angle of the impact trajectory was 30°. On clicking on the image in Fig. 1 the full video can be  played back that shows the impact process recorded with a high speed camera. The outer ring-like fold of the foil is a side effect of the experimental set-up.

Details of the experiment are as follows: Continue reading

Chiemgau impact: Pumice as an impact rock (impactite)

Pumice is a porous volcanic rock that is formed in gas-rich explosive eruptions on mixing of lava and water. When pressure releases, the melt froths by expansion of carbon dioxide and water vapor, and on rapid cooling the peculiar strongly vesicular texture forms. Pumice is nearly exclusively composed of glass with few mineral inclusions and has up to 90 % porosity which is why in general it floats in water. Depending on the source material and the texture pumice occurs in a broad color spectrum, from nearly white to yellow, gray and practically black. Well known is the Italian pumice from Lipari and Stromboli, and in Germany pumice from the Eifel volcanism is exploited.

Pumice from Lake Chiemsee

Since a few years the intensified geological investigations of the crater strewn field of the Chiemgau meteorite impact has revealed abundant finds of pumice cobbles in the shore region of Lake Chiemsee.

Fig. 1. Pumice varieties from Lake Chiemsee. White pumice – gray, marginally whitish pumice – gray pumice – grayish-black pumice (from top left to lower right). Samples by courtesy of Ernst Neugebauer.

The pumice occurs in various color varieties (Fig. 1) the white pumice rather being rare. Under the microscope the texture of the white form differs from the gray and grayish-black varieties (Figs. 2, 3). Continue reading

Shatter cones from the Lake Tüttensee crater (Chiemgau impact)

Shatter cones are conical fractures in rocks exhibiting typical fracture markings that are produced by shock waves and that belong to the well-known and reliable macroscopic shock features in rocks from meteorite craters (impact structures).

So far, shatter cones have never been found in the crater strewn field of the Chiemgau impact as a positive impact evidence, which we explained by the predominant uncemented loose sediments of the impact target. In this regard, a change of thinking is necessary since only recently clear shatter cone structures were detected in a rock sample from the Lake Tüttensee ring wall (Fig. 1).

shatter cones from the tüttensee crater, chiemgau impact meteorite crater strewn field

Fig. 1. Shatter cones with counter orientation from the Lake Tüttensee crater. Continue reading

Regmaglyptic cobbles from Lake Chiemsee: Evidence of meteorite impact-induced ablation features

Well known among people around Lake Chiemsee, peculiarly sculptured limestone cobbles (Figs. 1 – 4) found at the shore and offshore at the lake bottom attracted special attention when Lake Chiemsee got into the focus of the meteorite strewn field impact research. Although most people are considering the groove cobbles no more than a freak of nature, the work of organisms, especially of mussels has always been suggested.

Fig. 1. Typical conically shaped groove stone from the Lake Chiemsee shore – originally a Quaternary fluvio-glacial limestone cobble. Photo courtesy of H. Eberle.

Fig. 2. Various aspects of groove cobbles from Lake Chiemsee. Photos courtesy of H. Eberle and T. Schwaier.

Fig. 3. Big grooved limestone block from the Lake Chiemsee shore. Note the distinctly parallel, knife-edge ridges between the grooves (in the same orientation found all around the block) hardly compatible with the work of organisms.

Fig. 4. Pyramidally shaped groove stone. Note the geometrically orientated groves. Photo courtesy of H. Eberle.An impact-related formation came to the fore comparing the typical groove features with ablation features (regmaglypts) that meteorites may acquire when exposed to frictional heat on their passage through the Earth’s atmosphere. Moreover, an amazing similarity between the groove cobbles and regmaglyptic boulders from the Puerto Mínguez impact ejecta of the Spanish large Rubielos de la Cérida impact structure (Figs. 5, 6; also see the respective article: http://www.impact-structures.com/article%20text.pdf) exists. When we suggested that the cobble grooves were formed in the Chiemgau impact event as ablation features having developed by decarbonization and carbonate melting upon ejection and heating in a jet of super-heated volatiles, immediate reactions of local geologists ensued.

As later adopted by the local geologist Dr. Robert Darga, Dr. Robert Huber from the university of Bremen rejected the impact model of groove formation and instead seized again on the old explanation of the work of organisms, especially of bacteria and algae. He underlined his belief claiming that the same groove cobbles are a common feature in many lakes in the Alpine Forelands, Lake Constance included – see his blog contribution http://stratigraphynet.blogspot.com/2008_06_01_archive.html. We encourage you to read his remarks and to especially enlarge the photos in Dr. Huber’s blog comparing them with our photos from Figs. 1-4. It’s like comparing apples to oranges. And until today, Dr. Robert Huber fails to present groove cobbles like those shown in our figures from lakes other than Lake Chiemsee.

Of course, biogenic rock sculpture produced by organisms like, e.g., endolithic bacteria or piddocks is a well-known process, but once more, we must not compare apples to oranges, and obviously Dr. Huber has come to a deadlock.

There are very simple macroscopic observations proving the inorganic formation of the grooves. As shown in many of our photos, the grooved cobbles frequently exhibit distinct conical and pyramidal shape while the grooves, in most cases showing extremely sharp, knife-like edges, are geometrically related with the cones and pyramids. It’s exactly the same observation we are making with the regmaglyptic stones from the Rubielos de la Cérida impact ejecta (Figs. 5, 6). If the grooves were produced by organisms, these bacteria, algae and mussels must have had extraordinary intelligence, organization and communication capabilities to geometrically sculpture a large block as seen, e.g., in Fig. 3. Moreover, the identically grooved stones from the Spanish impact ejecta have never seen a lake, as can be read in more detail in the article referred to above.

In summary, a biogenic origin of the unmistakable, distinctly grooved cobbles from Lake Chiemsee has not any reasonable base. Instead, all features, the frequently conical and pyramidal orientations included, point to an erosion process initiating ablation due to decarbonization and melting.

Meanwhile, new finds of quite a few grooved cobbles (among them also grooved sandstones) substantiate the impact-related formation and, moreover, give highlighting insight into the unique process of deposition of the cobbles after having acquired their sculpture. We will report soon.

Fig. 5. Big grooved limestone clast embedded in the diamictic impact ejecta of the Rubielos de la Cérida impact structure in Spain. Note the pyramidal shape and the grooves diverging from the top of the pyramid.

Fig. 6. Regmaglyptic conically shaped limestone clast from the Puerto Mínguez ejecta of the Spanish large Rubielos de la Cérida impact structure. The clast that never saw any biogenic activities in a lake has remarkable similarity with the Lake Chiemsee groove stones.

An impact layer at Chieming-Stöttham


More than 30 excavation pits in the environs of Lake Tüttensee have encountered an impact layer that is suggested to be ejecta from the formation of Lake Tüttensee as a meteorite crater in the Chiemgau impact event [http://www.chiemgauimpact. com/artikel2.pdf]. Now, a very similar situation has been found with archeological excavations in the border area of Lake Chiemsee near Chieming-Stöttham. Undisturbed glacial drift with a fossil soil is overlain by a layer that must be interpreted as the result of a catastrophic event in the recent geological time. Like at Lake Tüttensee, the layer is composed of a multicolored mixture of deeply corroded rock fragments in a clayey matrix. Organic material like charcoal, teeth and bones as well as archeological objects are intermixed. This “catastrophe” horizon is overlain by a younger undisturbed occupation layer (Roman) and recent soil formation. Similar to Lake Tüttensee, the archeological finds and the geologic-archeological stratigraphy date the catastrophic event to have happened many thousand years after the end of the glacial period.

Fig. 1. The excavation pit and layering at Chieming-Stöttham exposing the “catastrophe”horizon (light, roughly in the middle of the image)

Fig. 2. Close-up of the impact catastrophe layer.

Because of the great distance to Lake Tüttensee, a formation of the Stöttham “catastrophe” horizon as ejecta from that crater can be excluded. Instead we propose another nearby impact, and there is some evidence that an impact into Lake Chiemsee was involved at least

Fig. 3. Another exposure in the area of the archeological excavation. Here, the roughly 2 m deep pit cutting through the “catastrophe” layer has not encountered the autochthonous ground moraine. In comparison with Fig. 1 the exposure shows the fluctuation of thickness and composition of the layer. Many of the dark components are intermixed charcoal.

A new geophysical campaign at Lake Tüttensee crater

Geophysical measurements play an important role in the research on meteorite craters (impact structures). The unusual pressures, temperatures and mass movements closely related to meteorite impact result in partly drastic changes of the physical properties of the target rocks. These changes correspond to characteristic geophysical anomalies, and many a crater buried deeply in the Earth’s crust have first been discovered by geophysical soundings.

In an earlier geophysical gravity survey at Lake Tüttensee, a peculiar ring of positive gravity anomalies was measured to have possibly resulted from a shock densification [article]. Now, we conducted a new campaign of geophysical measurements in the zone of impact ejecta that have been encountered in more than 30 excavation pits around Lake Tüttensee.

Fig. 1. Klaus Ebinger (to the left), owner of the EBINGER company, during the Tüttensee crater geophysical campaign.

 

 Fig. 2. Pulse electromagnetic (TEM) survey at Lake Tüttensee using the EBINGER UPEX 740 M Large Twin Loop equipment.

 

The geophysical survey comprised pulse (TEM) and frequency (FEM) electromagnetic soundings, and the primary objective was an area-wide investigation of the impact-related geological underground und its peculiarities so far only known from selective excavations around Lake Tüttensee.

The campaign was generously supported by the EBINGER company (Cologne) [Ebinger Prüf- und Ortungstechnik GmbH], a worldwide operating producer of high-tech search and detection equipment (Fig. 1). The EBINGER products are applied to various fields like unexploded ordnance (UXO) disposal both by sea and by land, safety engineering, environmental geophysics, industry and research, and in this particular case the EBINGER company in a three-day campaign (Fig. 2) supported at no charge the research of the Chiemgau Impact Research Team (CIRT).

From that campaign, Fig. 3 shows an example of processed pulse-electromagnetic (TEM) data sampled on an area of 150 x 100 m². The map exhibits conspicuous resistivity contours that, however, need further interpretation.

Fig. 3. Pulse-electromagnetic (TEM) resistivity mapping at Lake Tüttensee crater using EBINGER Large Loop equipment.