Transdanubian volcanic region
The Transdanubian Volcanic Region is a long, fossil volcanic arc in southern Europe that stretches from Slovenia through southern and southeastern Austria to the border between Burgenland and Hungary .
Some geologists see a large tectonic connection with the Periadriatic Fault Line , which extends eastward from northern Italy and whose geometrical continuation forms the volcanic arch.
Geological and geographical overview
The slightly curved arch consists of a few dozen extinct volcanoes that formed in an almost linear arrangement in the Young Tertiary - in the course of the Alpine folding of the mountains . The rise of its volcanic rocks is largely a consequence of the displacements that many geological formations have suffered from the pressure that the African plate exerted against the continental block of Europe during the alpine mountain formation for at least 30 million years and continues to do so today. The African continental plate pushed itself over the European plate, whereby the rock melted underground and rose to the surface of the earth as magma (similar processes still occur today in the subduction zones around the Pacific).
The volcanic arc begins in present-day Slovenia south of the Bachergebirge and continues with young tertiary volcanic deposits in the south of Austria ( Carinthia and Southeast Styria ): It crosses the Lavant valley and runs to the eastern Styrian hill country , where the largest number of former volcanoes can be found. On average, an island of volcanic (mostly very hard) rocks emerges here every 10 km. In southern Styria, such mountains can be found, for example, at Weitendorf ( Weitendorf basalt quarry ) and Klöch , continue in Stradnerkogel (610 m) and the Gleichenbergs (north of the thermal springs of Bad Gleichenberg) and slowly turn their course to the north. The next striking volcanoes are the Steinberg near Feldbach and the steep tuff chimney on which the famous, never conquered Riegersburg sits. The volcanic arch crosses the border with Burgenland via some volcanic units near Fürstenfeld , passes the Günser Mountains and forms the last high volcanic cone in Pauliberg near Kobersdorf ( Oberpullendorf district ). The Pauliberg is the youngest volcano in Austria and was probably active until about 2 million years ago. Due to its hardness, the basalt mined there is one of the building materials with the greatest durability worldwide .
A volcano near Oberpullendorf formed the hilltop (Fenyös erdö) west of the center of Oberpullendorf. This volcano consists of two superimposed lava flows. It is dated to the time before or around Sarmat .
In the west of Vienna , evidence of volcanic activity was also found during the construction of a water reservoir in the Lainzer Tiergarten near Mauer . Volcanic rocks ( picrites , tuffs ) were also observed in other places in the wall and its surroundings . Sea mussels have drilled holes in the rocks. The activity of the volcanoes is estimated at an age of about 12 million years and thus in the Miocene .
Genesis of the volcanic chain
In a report, the Leoben geophysicist Leopold Weber (co-author) examined a part of this Transdanubian volcanic region in Styria and formulated its formation as follows:
“If you only look at the volcanism of the East Styrian basin [...], you can distinguish between two types of volcanic activity, which differ in the chemistry of their rocks on the one hand and in the time of their formation on the other. The first volcanic activity in south-eastern Styria occurred in the Miocene around 17 million years ago. This "acidic" volcanism produced rocks mostly in the form of flat shield volcanoes. During the daytime, these products of this volcanic activity are only exposed in the area north of Bad Gleichenberg (Gleichenberg). The actual extent of these “acidic volcanic rocks” has only become known through deep drilling. After the East Styrian basin at the time of this older volcanic activity was a sea divided into partial basins by swells, the Styrian basin in the Sarmat began to constrict and gradually silted up after a new sea invasion from the south. "
According to the report, a second volcanic phase occurred in the Gelasian 1.8-2.5 million years ago. In contrast to the first, this volcanic activity brought mainly "basic volcanic rocks" to the surface of the earth. The expert recognizes them in the form of numerous breakthrough tubes which "[...] sometimes produced ceiling-shaped lava effusions in the surface. In some places only tuff chimneys are preserved, such as B. the castle rock of the Riegersburg, or you can still see the structures of former boiler craters ”- such as in the basalt quarry of Klöch (Styria).
Example of the basalt quarry of Klöch (Styria)
The northern part of this massif is the Kindbergskogel . It is an embankment cone made of volcanic slag and tuff with radial crevices into which basaltic material penetrated during later extrusions . In the southern part of the Klöcher massif, on the other hand, there is a basalt-filled basalt crater. The Klöch quarry is located in this solid basalt . The caldera itself is a finer tuff cover, the sedimentary base of which has sunk.
The basalt is with Böhler Bohrraupen in a 4 m-grid and subsequent blasting degraded. The annual drilling capacity of 52 km by 9 cm enables an annual production of over 950,000 tons. The four crushers of the processing plant produce around 350,000 Mt of fine crushed grain and 550,000 t of gravel for civil engineering; the unbroken remainder is used for hydraulic engineering , soil improvement and embankment.
Basalt on Pauliberg (Burgenland)
The end of the volcanic arch is roughly marked by the Pauliberg near Kobersdorf , Oberpullendorf district. The very compact, 761 m high mountain consists largely of basalt and is the youngest volcano in Austria, which was probably active about 2 million years ago. A quarry has long been located near the summit; Due to its hardness, the basalt mined there is one of the building materials with the greatest durability worldwide.
The Pauliberg lies in the transition area between the Eastern Alps and the Pannonian Plain , about halfway between the towns of Kobersdorf and Landsee (near Sankt Martin ). Pauliberg volcanism began around 20 million years ago and extended into the Pliocene . A cave, the "four-hole cave", is embedded in a lava tongue . This peculiarity is the only secondary basalt cave in Burgenland. The basalt dome breaks through the sequence of alternating rocks and is therefore the only one in the chain of Pliocene volcanic mountains of the Eastern Alps to lie on the crystalline . The alternating rocks that occur around Landsee form the eastern part of the " Wiesmather Window ".
See also: Geschrittenstein , Thermenlinie , Geschrittenstein-Írottkő Nature Park , Stradner Kogel , Semmering window
Web links
- Styrian volcanic land
- Regional Geology ( Memento from January 19, 2007 in the Internet Archive ) (PDF file; 3.36 MB)
- Pannonian Nature Parks ( Memento from September 28, 2007 in the Internet Archive )
literature
- Leopold Weber : excursion to the Pauliberg basalt works and introduction to steir. "Vulkanbogen", Proceedings Bergbautechnik Heft 12, Ministry of Economics Vienna 2000.
Individual evidence
- ^ Friedrich Kümel: volcanism and tectonics of the Landseer Bucht in Burgenland. Yearbook of the Federal Geological Institute. Volume 86 Vienna 1936. Pages 203–235 (on the volcano see page 233), PDF on ZOBODAT
- ↑ Josef Stiny, Friedrich Trauth: The building site for the new water tank in the Lainzer Tiergarten . Yearbook of the Federal Geological Institute . Volume 88, Vienna 1938. Pages 35–48 ( PDF )
- ↑ An extinct volcano at the gates of Vienna. Daily newspaper "Reichspost" from November 7, 1937, No. 307/1937, page 9
- ^ Heinrich Küpper: On the knowledge of the Alpine breakup on the western edge of the Vienna basin. In: Yearbook of the Federal Geological Institute. 94th Volume Part 1, Vienna 1951. Pages 41–92, the article is mentioned on ZOBODAT