Suevite

Suevite is a Impaktit, a rock that is formed by the impact of a meteorite. Typically Suevite next crushed bedrock and Impaktglas solidified melts some minerals that occur only at extremely high pressures and temperatures, such as stishovite, coesite and diaplectic glasses. Remnants of the impactor can also be included. Originally the suevite in the Ries was described, where the name derives from the Latin Suevia in Swabia. Today Suevite also from numerous other impact craters are known.

Suevite in the Ries

The suevite was first described in 1792 by the engineer Carl Caspers under the name Fire aroma stone. Caspers used in the expansion of the rock fortress of Ingolstadt as Trass for the production of waterproof cement. The geologist Adolf Sauerland initiated in 1919 for the well-known at that time only from the Ries suevite rock from the name from the Latin for Suevia Swabia. For a long time the suevite as volcanic rock, similar to the tuff viewed. It was not until around 1960 was the origin of the Ries crater, and hence that of the suevite, be explained by an impact. Found in suevite high-pressure minerals stishovite and coesite played a central role. Even the dating of the impact on an age from 14.3 to 14.5 million years ago was possible by examining the melting glasses and Moldavite.

Formation

When Ries event before approximately 14.4 million years ago when the explosive vaporization of the meteorite and the surrounding rock were ejected large quantities of crushed rock and molten rock. 1981 were found by Günther Graup first terrestrial chondrules in the suevite of the Ries crater, which have structural similarities to meteoritic chondrules. Since the formation of lunar and meteoritic chondrules is still unknown, while the formation of meteoritic collisions appears as a possible explanation. 1999 structures by Günther Graup were first described from the Auswurfsuevit, demonstrating that during the impact event caused large quantities of Carbonatschmelzen (up to 50 vol %), which were formed from the Malmkalken of the impact area. The embedded in suevite glasses ( " pancake " ) were formed from the Mesozoic shales of the impact zone show petrographic data indicate that the fine-grained matrix consists to a significant proportion of thermally altered sediments. Several findings ( eg, grain size distribution, is regulated components, fine-grained Basistuff, degassing ) show that the ejection mechanism of the pyroclastic flow ( ignimbrite ) resembles (Lit.: Baier, 2012). The embedded in suevite melt glasses are evidence of temperatures up to 1950 ° C. Through the detection of multiple metastable high-pressure modifications and petrographic findings can be demonstrated that the cooling history of the Suevits quickly was (Lit.: Graup 1999, Baier 2007).

Occurrence

Holes in the Ries have shown that the Ries crater is up to 400 meters high filled with suevite. This Rückfallsuevit was later overlain by sediments of the lake formed after impact is superficial and therefore no longer accessible. In the vicinity of the Ries however Auswurfsuevit is to be found in isolated occurrences with an extension of up to one square kilometer and a thickness of up to 25 meters. This is always on the ejected from the Ries Bunte debris masses. It can be concluded that the suevite was deposited from the pyroclastic flow of the impact after the ballistic ejection of debris masses was completed from the crater.

In superficial suevite deposits the stored in the matrix glass bombs sense of occasion, and can then be read as isolated finds. Because of its shape, which have received this Impaktgläser when they were thrown in viscous state into the air, they are popularly referred to as pancake ( pancake, pancakes ).

Use

Since the porous Suevite is easy to work and moreover has excellent insulation properties, it is used in the vicinity of the Ries since Roman times as a building block. Numerous built from Suevite buildings, including the Nördlinger St. George's Church with its 90 meter high tower Daniel or the ruins of Lower House testify. Since the suevite is attacked by the increasing air pollution and by nature is very porous, restoration work on the historic Baubeständen today, performed with a deceptively similar stone to which small amounts are added to natural Suevits.

Comminuted Suevite (so-called ream Trass ) was since the above-mentioned description of the " fire scent stone " by Carl Caspers used as an admixture for cement. For certain special cements the suevite can still find use so that it is mined industrially in some quarries.

Ground surface of the Suevits from Nördlingen

Suevite with dark glasses from the impact crater of Lahojsk ( Logoisk ) in Belarus

Suevite from the impact crater of Manicouagan in Quebec, Canada