Wengenhausen impact rocks
The Wengenhausen impact rocks are located in a quarry near Wengenhausen, a part of the municipality of Marktoffingen in the Swabian district of Donau-Ries in Bavaria .
location
The quarry is located about 450 meters northwest of Wengenhausen. The area is designated as a protected landscape component.
description
In the south-eastern part of the former quarry there are strongly fissured crystalline rocks , which are covered by crystalline breccia several meters thick . In the northern part of the quarry lies the freshwater limestone of the former Ries lake above the crystalline breccia.
So-called " shatter cones " were found in the shattered crystalline rocks of the former quarry . Cones of rays form when exposed to high pressures and are proof that the Ries crater of the Nördlinger Ries was created by a meteorite impact . The yellow colored sediments of the crater lake can be seen at the upper edge of the outcrop . Below are the rubble rocks of the crystalline basement. The " polymictic crystalline breccia " consists of fragments of different crystalline rocks such as gneiss , granite or amphibolite .
About 14.5 million years ago, at the time of the Tertiary , a meteorite about one kilometer thick hit the transition area between today's Swabian and Franconian Alb at a speed of about 70,000 km / h. Its impact energy was equivalent to the energy of 250,000 atomic bombs of the type used in Hiroshima . The meteorite broke through 600 meter thick deposits from the Jurassic and Keuper times and shattered the underlying crystalline basement to a depth of six kilometers. Rocks were broken, transformed, ejected, melted or evaporated, as was a large part of the meteorite. As a result of the spring back of the crater floor, the crystalline basement, which is otherwise underground, came to the surface. What remained was a crater with a diameter of 25 kilometers, followed by large-scale ejecta. Seconds after the impact, a wave of pressure and heat extinguished life in a wide area.
Subsequently, an outflow-free lake was created in the impact crater, which fell dry several times at times. Streams and streams of mud washed in rock debris and formed massive lake deposits. Fossil-rich limestone formed in shallow bank areas. After around two million years, the crater was completely filled with deposits.
Scientists have been studying the Nördlinger Ries and its rocks for more than 200 years. For a long time it was assumed that the crater was formed by volcanic origin. In order to explain foreign rocks and polished surfaces, even a "Ries glacier" was wrongly applied as a theory. In 1904 the Schwäbisch Gmünder merchant Ernst Werner first expressed the theory of the origin of a cosmic impact. However, evidence for this theory was not found until 1961. Then the minerals coesite and stishovite were discovered in suevite (also called Schwabenstein) . These are special forms of quartz that are only formed at extremely high pressures such as a meteorite impact.
Recently another mineral has been found in the suevites that is only produced at very high pressures. They are microscopic diamonds , so-called impact diamonds .
Geotope
The quarry is designated by the Bavarian State Office for the Environment (LfU) as a geoscientifically particularly valuable geotope (geotope number: 779A012). It was also awarded the official seal of approval for Bavaria's most beautiful geotopes by the LfU .
See also
Individual evidence
- ↑ Location of the quarry in the Bavaria Atlas (accessed on November 2, 2017).
- ↑ Johannes Baier, Volker J. Sach: Shatter-Cones from the impact craters Nördlinger Ries and Steinheimer Becken . In: fossils . 2018, 35 (2), pp. 26–31.
- ↑ Volker J. Sach, Johannes Baier: New investigations on radiant limestone and shatter cones in sediment and crystalline rocks (Ries impact and Steinheim impact, Germany) . Pfeil-Verlag, Munich 2017. ISBN 978-3-89937-229-8 .
- ^ Bavarian State Office for the Environment, Geotop Impaktgesteine NW von Wengenhausen (accessed on November 2, 2017).
- ↑ Bavaria's most beautiful geotopes, Wengenhausen impact rocks (accessed on November 2, 2017)
Web links
Coordinates: 48 ° 54 '46.3 " N , 10 ° 27' 40.7" E