Northwest Saxon Depression
In geology, the term Northwest Saxon Depression refers to an intramontane sedimentary basin in Saxony that was created in the Permian and mainly contains Rotliegend deposits. The Rotliegend sequence is characterized by a high proportion of volcanoclastic and also intrusive and extrusive volcanic rocks, which include the “ Rochlitzer Porphyry ”, a stone that has been used for centuries . Kaolin deposits emerged from the intrusive rocks due to weathering . a. The State Porcelain Manufactory Meissen also purchased its kaolin. Even today, around a third of the kaolin contained in the total mass of around 550,000 t of hard and sanitary porcelain produced in Germany comes from the Kemmlitzer district between Leipzig and Meißen.
location
The Northwest Saxon Depression covers roughly an area that extends in the west from the Altenburger Sattel (west of Rochlitz , south of Borna ) to a little south and east of Oschatz in the east and to the north of Eilenburg . In terms of area, it covers about 2000 km². In terms of natural space, it essentially corresponds to the North Saxon plateau and hill country , smaller parts of the Leipzig country and the central Saxon loess hill country .
geology
The North West Saxon Valley is a large area on the variskisch scale tectonic units of the Great North Saxon Synklinoriums and North Saxon Anticline on, larger at the junction of fault systems that are responsible for the characteristic of this basin volcanism. It is essentially limited by SW, NE and SE-NW trending disturbances. It contains up to 1450 m of terrestrial and pyroclastic sediments as well as lavas and intrusives (additive thickness).
Structure of the sequence of layers
The structure of the shift sequence and the sequence of some shift members is still being discussed in part. It is placed in the lower red lying, the upper red lying is missing. The coarse clastics that were previously placed in the Rotliegend near Frohburg and Geithain are now regarded as terrestrial equivalents of the Zechstein . The structure used here for the layers in the Northwest Saxon Depression follows the "Geology of Saxony":
- Wurzen formation , about 600 m extrusive and intrusive volcanic rocks (andesitoids and andesitoide pyroclastics)
- Oschatz Formation , about 150 to 250 m thick volcanic rocks (lavas and pyroclastics), limnic-fluvial, tuffitic sand, silt and clay stones, fanglomerates, conglomerates and so-called fire slate as well as lacustrine black slate
- Rochlitz formation , approx. 400 m Ignimbrite
- Kohren formation , approx. 150 to 200 m, tuffitic siltstones and sandstones, fanglomerates, tuffs, volcanic rocks (lavas and ignimbrites)
Economical meaning
The Northwest Saxon Depression and its Rotliegendsediments are mainly known from the economic point of view for the stone that was mined in many places at different levels. In the 19th century, the so-called "fire slate" were also mined. There were also mining attempts on thin coal seams. In the middle of the 20th century the sediment filling was examined by the SDAG Wismut for uranium exposure, but unsuccessfully. The "Kemmlitzer Porphyry" is interpreted as a starting material for the mighty kaolin deposits in Baderitz and Kemmlitz . The State Porcelain Manufactory Meißen obtained its kaolin from Baderitz from around 1840.
swell
literature
- Werner Pälchen and Harald Walter (eds.): Geology of Saxony Geological structure and development history. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermüller), Stuttgart 2008.
- Harald Walter: The Rotliegend of the Northwest Saxon Depression. Publications of the Museum für Naturkunde Chemnitz, 29: 157–176, Chemnitz 2006
Individual evidence
- ^ A b G. Schwerdtner, H. Anger, M. Störr: The kaolin deposits of the Kemmlitzer Revier mining monograph. Mining in Saxony, 13: 116 S., Freiberg 2007 (Link to PDF , 9.15MB)
- ↑ Christoph Breitkreuz, Uwe Hoffmann, Axel D. Renno and Klaus Stanek (eds.): Third VENTS Field workshop , May, 15th to 18th, 2008, Abstract volume and Field guide on the Late Paleozoic magmatic evolution of Saxony TU Freiberg (Link zu PDF)
- ↑ Pälchen & Walter (2008: p 233ff.)
Web links
- Dietrich Franke: Regional Geology of East Germany - A Dictionary , 2012
- Figure 31: Geology of the Northwest Saxon Eruptive Complex , PDF, 356 kB
Remarks
- ↑ As a brand shale refers mixed with thin carbon layers shales . The coal and the shale can also appear in alternating layers. Fire slate has a high ash content. (Source: Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: Das kleine Bergbaulexikon .)