Saxon Granulite Mountains

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Historical geological map of Saxony (1930) without a thin Quaternary overburden. The Saxon Granulite Mountains can be seen as an oval, predominantly light pink area in the center of the left half of the map (Mittweida area), northwest of the Erzgebirge basin shown in light orange ( red lying ) and southeast of the northwest Saxon volcanic complex shown in red (" porphyry ").
The rock base of Rabenstein Castle in the west of Chemnitz consists of a phyllite-like slate of the shell complex of the granulite mountains. The border to the Erzgebirge basin runs just a few hundred meters southeast of this location.

The Saxon Granulite Mountains are a regional geological unit in Saxony , which connects to the north-west of the Vorerzgebirgs-Basin and the Osterzgebirge . Structurally, it is a dome-like saddle . In the map, this forms an ellipse with a south-west-north-east running longitudinal axis, which extends over about 50 km from Hohenstein-Ernstthal to Roßwein . The northwest-southeast extension (the "width" of the ellipse) is about 20 km. The elliptical shape can only be seen well on so-called covered geological maps, as the granulite mountains are covered in large parts by Cenozoic sediments. The Saxon Granulite Mountains are the world type region for the granulite facies .

The core complex of the dome structure consists predominantly of leucocratic granulite , a transformation rock formed under high pressure and temperature . It is surrounded by an inner and outer slate coat. The original rocks of the granulites were formed in the Proterozoic and transformed during the Variscan orogeny . However, the granulite core also contains enclaves from other rocks, for example a granite island near Mittweida and other smaller elongated granite bodies. The granites are of the Carboniferous age and are therefore the youngest formations of the Granulite Mountains. They only penetrated the granulite after the metamorphosis and were therefore subject to far less tectonic stress.

The outer slate mantle consists mainly of greywacke , clay slate and phyllites . The rocks of the inner slate mantle show a higher degree of metamorphosis than those of the outer slate shell. They are made of light and dark mica ( muscovite - and biotite mica schist) and various gneisses (biotite, cordierite - and garnet gneiss ). The gabbro deposits of Langenberg near Callenberg and the bronzite - serpentinites of the Kiefernberg near Hohenstein-Ernstthal lie between the slate mantle and the granulite core .

Web links

Commons : Sächsisches Granulitgebirge  - Collection of pictures, videos and audio files

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General

Individual evidence

  1. ^ DEKORP, Orogenic Processes Working Groups: Structure of the Saxonian Granulites: Geological and geophysical constraints on the exhumation of high-pressure / high-temperature rocks in the mid-European Variscan belt. Tectonics. Vol. 18, No. 5, 1999, pp. 756-773, doi: 10.1029 / 1999TC900030 ( Open Access ).