Grauwackenzone

The Grauwackenzone lies between the Central Alps and the Northern Limestone Alps . The mostly dark rocks were already folded once during the Variscan mountain formation and then a second time during the formation of the Alps .

The (Northern) Grauwackenzone stretches as a narrow strip of paleozoic rocks from the Arlberg through the Upper Inn Valley , then widens in the area of ​​the Tux , Kitzbühel Alps and Salzburg Slate Alps  - this wider section is called the Slate Alps - to the Dachsteinstock , and then back to one in the Ennstal very narrow width to converge ( Ennstalphyllitzone ) . In the Eisenerzer Alps it reaches a greater width and then runs through the Mürz Valley and the Semmering into the Vienna Basin ( Ternitz ).

As mountain-forming material, phyllite , slate , metamorphic volcanic rocks , furthermore weakly metamorphic limestones ( marbles ), quartzites and the eponymous - but in the narrower sense only subordinate - greywacke are predominant. The Grauwackenzone is rich in natural resources (iron, copper, magnesite, graphite, etc.). Due to the mostly soft rock, the mountains are predominantly rounded, gentle peaks with little forest , which are attractive for alpine skiing .

Geologically, the Grauwackenzone was formed when the Alps unfolded from the seabed of the ancient Mediterranean Sea, Tethys , while the limes deposited on it form the stocks , karst plateaus or walls of the limestone Alps. The Northern Greywacke Zone, together with the Grazer Paläozoic and Gurktaler Nappe , belongs to the eastern alpine nappes, namely to the Oberostalpin (Upper Central Eastern Alpine ), which rests on the old crystalline of the Middle Eastern Alpine (Lower Central Eastern Alpine ).

Stratigraphically simplified, the rock stock is as follows (there are of course many differences between Arlberg and Semmering):

• Ordovician : slate, phyllite, meta - conglomerates and metamorphic volcanic rocks - especially the widespread Blasseneck porphyroid. Significant mountain peaks from west to east z. B. Gampenkogel and Steinbergkogel (both Kitzbühel Alps ), Blaseneck (Blasseneck) and Leobner (both Eisenerzer Alps )
• Silurian : slate, phyllite, green schist (metamorphic volcanic rocks), greywacke and weakly metamorphic limestone. Important mountain peaks z. B. Geißstein , Hundstein
• Devonian : v. a. metamorphic limestones, often containing ore such as B. on the Erzberg , on the Mitterberg near Mühlbach am Hochkönig and in Schwaz . Important mountain peaks from west to east: z. B. Gratlspitze , Großer Rettenstein , Kitzbüheler Horn , Wildseeloder , Spielberghorn, Zeiritzkampel , Wildfeld , Eisenerzer Reichenstein , Polster , Gößeck ( Reiting ), Turntaler Kogel
• Carboniferous : slate, phyllite and weakly metamorphic limestones, some containing magnesite, as in the sunk at Trieben (Triebensteinkalk) and in Veitsch

In some places a southern Grauwackenzone also appears in the south of the Central Alps , e.g. B. in the Carnic Alps .

See also

• Tauern and Semmering windows
• Paleozoic , metamorphic rocks

literature

• F. Neubauer, Robert Handler, Siegfried Hermann, Gernot Paulus: Revised lithostratigraphy and structure of the eastern greywacke zone (eastern alpes). In: Mitt. Österr. Geol. Ges. 86 Vienna (1995), pp. 61-74 (English; eReader , researchgate.net).

Individual evidence

1. ↑ Hans Wieseneder : About the rock designation Grauwacke. In: Mineralogy and Petrology , Volume 7, Number 4 (1961), pp. 451-454 ( doi: 10.1007 / BF01127754 ).
2. ↑ Hans Peter Cornelius: Rocks and tectonics in the eastern section of the northern Alpine Grauwackenzone, from the eastern edge of the Alps to the Aflenz basin. In: Communications from the Geological Society in Vienna , 42. – 43. Volume, 1949–1950, pp. 1–234 (especially p. 12 bottom; PDF , 10.3 MB; uibk.ac.at).