Every four years the International Union of Geosciences (IUGS) coordinates the International Geological Congress.
After a contribution at the 33th congress 2008 in Oslo the CIRT had now a presentation at the this year’s meeting in Brisbane, Australia:
A prehistoric meteorite impact in Southeast Bavaria (Germany): tracing its cultural implications
Barbara RAPPENGLUECK, Kord ERNSTSON, Ioannis LIRITZIS, Werner MAYER, Andreas NEUMAIR, Michael RAPPENGLUECK and Dirk SUDHAUS
Abstract. – A meteorite crater field in Southeast Germany, the Chiemgau region, comprises more than 80 craters scattered in an area of about 60 km x 30 km. The crater diameters range between a few meters and 600 m, forming one of the biggest known areas of Holocene meteorite craters. Continue reading “Chiemgau impact: presentation at the 34th International Geological Congress, 5-10 August 2012 – Brisbane, Australia”
The Chieming-Stöttham archeological excavation – comments on a recently published article
by Chiemgau Impact Research Team (CIRT)
Abstract: – At the behest of the Bavarian State Office for Monument Preservation (BLfD) the archeological excavation at Stöttham near Lake Chiemsee, which exposed an intercalated geological layer with all evidence of a catastrophic deposition in a meteoritical impact event, was accompanied by a study performed by Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt der Technischen Universität München [Science Center of Nutrition, Land Use and Environment, Technical University of Munich, at Weihenstephan]. In the now published article the exposure is most widely described and interpreted from a geomorphological and soil science perspective while the unambiguous impact features implying the typical heavy rock deformations and shock metamorphism (shock effects) are completely ignored. Nevertheless, the authors conclude that there are not any indications of an impact event. Here, we remind of the progress of events, discuss the major shortcomings of Völkel et al.’s article, and conclude that it doesn’t meet scientific requirements. Continue reading “Chiemgau Impact – a new article: Jörg Völkel, Andrew Murray, Matthias Leopold, and Kerstin Hürkamp: Colluvial filling of a glacial bypass channel near the Chiemsee (Stöttham) and its function as geoarchive. – Zeitschrift für Geomorphologie (Annals of Geomorphology), 56(3), 371-386, 2012.”
… or a “Requiem” for the rejection of the hypothesis?
YDB abbreviates Younger Dryas Boundary. The Younger Dryas stadial signifies a sharp onset of a period of cold climatic conditions in Earth’s history lasting roughly 1,000 years between about 11,000 and 10,000 B.C. at the end of the Pleistocene (the “Ice Age”) and the beginning Holocene.
The causes of this event are controversially disputed, and they are conventionally ascribed to perturbations of North Atlantic circulation. In 2007, a new hypothesis on a giant meteorite impact Continue reading “YDB impact: a new chapter”
Experimental hypervelocity impact crater generation and the formation of the Lake Tüttensee crater
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).
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: conducting hypervelocity impact experiments”
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 “Chiemgau impact: Pumice as an impact rock (impactite)”
Presentation: 43. Lunar and Planetary Science Conference (LPSC), March 19–23, 2012, The Woodlands, Texas, USA: http://www.lpi.usra.edu/meetings/lpsc2012/programAbstracts/view/
Shumilova T. G.1 Isaenko S. I.1 Makeev B. A.1 Ernstson K.2 Neumair A.3 Rappenglück M. A.3: Enigmatic Poorly Structured Carbon Substances from the Alpine Foreland, Southeast Germany: Evidence of a Cosmic Relation [Abstract #1430]
1Institute of Geology, Komi SC, Russian Academy of Sciences, Pervomayskaya st. 54, Syktyvkar, 167982 Russia, 2Faculty of Philosophy I, University of Würzburg, D-97074 Würzburg, Germany, 3Institute for Interdisciplinary Studies, D-82205 Gilching, Germany.
The study deals with a so far unknown impactite from the Chiemgau meteorite crater strewn field incorporating a high pressure/high temperature carbon allotrop.
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).
Fig. 1. Shatter cones with counter orientation from the Lake Tüttensee crater. Continue reading “Shatter cones from the Lake Tüttensee crater (Chiemgau impact)”
At the AGU (American Geophysical Union) Fall Meeting, December 5-9, two contributions focusing on special features of the Chiemgau meteorite impact strewn field have been presented:
Neumair, A. & Ernstson, K. (2011), Geomagnetic and morphological signature of small crateriform structures in the Alpine Foreland, Southeast Germany, Abstract GP11A-1023 presented at 2011 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec.
The poster may be clicked here: Poster Neumair & Ernstson
Ernstson, K. & Neumair, A. (2011), Geoelectric Complex Resistivity Measurements of Soil Liquefaction Features in Quaternary Sediments of the Alpine Foreland, Germany, Abstract NS23A-1555 presented at 2011 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec.
The poster may be clicked here: Poster Ernstson & Neumair
Article on the Thunderhole phenomenon in the Chiemgau impact area:
The sinkhole enigma in the alpine foreland, Southeast Germany: Evidence of impact-induced rock liquefaction processes
Kord Ernstson, Werner Mayer, Andreas Neumair and Dirk Sudhaus
The article describes the very first geologic and geophysical investigations of the so-called Thunderhole (“Donnerloch“) phenomenon in the region of the small town of Kienberg north of Lake Chiemsee in Southeast Bavaria. The authors conclude that the innumerable enigmatic sudden sinkhole cave-ins having happened in living memory originate from late and even today acting processes of an earlier shock-induced underground rock liquefaction known from strong earthquake shocks. The geologically prominent underground structures that have now been uncovered are considered the result of impact shocks in the course of the formation of the Chiemgau meteorite crater strewn field (Chiemgau impact).
Some characteristic images of this highlighting rock liquefaction (or soil liquefaction) process can be seen on continuing
Continue reading “Chiemgau impact: an article on the impact-induced soil liquefaction (rock liquefaction)”
The term spallation is used in various meanings, e.g. in nuclear physics and fracture mechanics. For impact processes, spallation plays an important role (however seldom appreciated appropriately) and is closely related with the propagation of shock waves. To put it simply, the process runs as follows: On impinging on a free surface, the shock compressive wave is reflected as a tensile wave of practically identical energy. And while a compressive pulse is squeezing a rock, a tensile pulse is stretching the material thus enabling the development of tensile fractures and in an extreme case leading to the detachment of a spall or series of spalls. This is favored by the fact that the tensile strength of all materials and, hence, also of rocks is considerably less than the compressive strength. This is why it is often disregarded that the enormous destructions upon meteorite impact are not so much the result of the shock wave pressure as of the pull of the rarefaction waves. Spallation may take place also when a compressive shock pulse impinges on a boundary of material with reduced impedance (= the product of density and sound velocity) where part of its energy is reflected as a rarefaction pulse that may likewise enable tensile fracturing. It is worth remarking, however compatible with shock physics, that the process of spallation can be observed on arbitrary scales, from microscopically small deformations right up to the movement of huge rock complexes.
Fig. 1. A limestone cobble (14 cm long) exhibiting the typical open spallation tensile fractures. The process is nicely documented by the observation that the running fractures have come to standstill midway through the cobble. In case they had continued running, the cobble would have been fractionized to pieces, and nothing of note would have remained. Continue reading “Shock spallation – a typical impact process in the Chiemgau meteorite crater strewn field”