Saar–Nahe Basin
The Saar -Nahe Basin is in geology a intramontane Molasse Basin (or Innenmolasse ), which was created at the end of the Variscan orogeny in Central Europe. It includes deposits from the Upper Carboniferous and Permian, which have a maximum thickness of up to 8000 m. Has or had economic importance the pool first by sideritische iron ores and later mainly by the intercalated coal seams.
Extent and location of
The Saar -Nahe Basin in the geological sense has a size of about 300 x 100 km, of which only about one-third, however, is open, ie comes to light; the rest is covered by younger deposits and detected only by drilling. It extends from the Rhine in the east to in the region of Champagne -Ardenne ( France) in the west. Already from the German - French border, the deposits of the Saar -Nahe Basin to the west are back covered by younger deposits. The total pool is therefore referred to in the literature as Lorraine -Saar -Nahe Basin. In the north it is relatively sharply limited by the Hunsrück southern edge disorder; the thickness is reduced to the north of the fault on a short or very short distance to 0 m. To the south it extends far below the younger cover to about at the northern edge of the Vosges mountains in the west and the northern Black Forest in the east. Seen tectonic basin forms a light today südvergente saddle structure. Within the Saar -Nahe Basin can be several sub-basins (eg Saar sub-basin, near- sub-basin ) recognize and Horst structures ( Sprendlinger Horst ), which are faults perpendicular to the Hunsrück southern edge disorder and who were active during the formation of the entire basin. The major disturbances were: Trombach disorder, Potzberg disorder, Lorraine disorder, etc.). They were active at different times and is responsible for the very different thicknesses of the formations, facies and also the displacement of the centers during the deposition of the Permian sedimentation in the Saar-Nahe Basin.
Formation
Through seismic surveys to know the structure of the Saar-Nahe Basin relatively well. It is a strongly asymmetric basin, whose greatest reduction or whose greatest thicknesses are on its northern side immediately south of the southern edge of the Hunsrück - disorder. It was created by a right-handed transtensive movement along the southern edge of the Hunsrück disorder, which later was also further overprinted as a right-handed shear surface. It is therefore to be interpreted as a right-handed blade displacement Basin (strike -slip fault basin ).
Deposits, delivery areas and age
During the depression of the Saar-Nahe Basin, a striking change in the climatic conditions of arid to tropical took place. Accordingly, the deposition conditions changed from limnic - fluvial, limnic - lacustrine to terrestrial - arid. The living world was exposed to a strong change.
With coarse conglomerates at the base and pelites at the upper boundary ( top ) heads the well-known only from boreholes Spiesen lineup a fluvial sedimentation of the Saar -Nahe Basin. It lies unconformably on marine Viseum and is dated to the Namurium. In the productive Upper Carboniferous follows ( productive because of the mineable coal seams ) with the Saarbrücken and Ottweiler groups. During the Westfaliums the center of the deposit lay south of today's open-minded strata of the Saar -Nahe Basin. The ablation area was located north in the Rhenish Slate Mountains, it provided siliciclastic sediments. During the Stefaniums the delivery area and the composition of the cobbles changed. From the Black Forest, the Vosges and the Massif Central region, ie from areas south of the basin, sediments were supplied with granitic clastic components. In this case, the center of the deposition shifted closer to the southern edge of the Hunsrück - disorder and along it from southwest to northeast. Hiatuses are present well within Westfalium A and B, the Namurium is not entirely due to its small thickness. The Westfalium D is unconformably overlaid by Stefanium. Within the Stefaniums no recognizable unconformities are present, the Permian layered concordant on the Stefanium. The chronostratigraphic boundary Carboniferous / Permian is by Boy & Schindler ( 2000), probably in the Wahnwegen lineup.
The lower part of the Permian still has predominantly gray-green - colored sedimentary rocks, which have a low amount of volcanic Aschentuffe that originate from outside the basin. In the higher part of the Permian deposits are colored predominantly red and contain a high proportion of andesitic and rhyolitic lavas latitischen - and Aschentuffen that have been supported within the basin. The sediments were deposited in vast lakes, deltas, river systems and alluvial fans.
Lithostratigraphic subdivision of the deposits
The deposits of the Saar -Nahe Basin can be understood in terms of lithostratigraphy as a super group. They are divided into three lithostratigraphic groups, Saarbrücken group Ottweiler group and Glan- group. The following further breakdown of these groups is done according to Shepherd (2005 ) and Boy in Mennig et al. (2005). Saarbrücken group and Ottweiler Group were deposited during the Upper Carboniferous, the Glan- group in the Permian. The two subdivisions differ in the Permian share, so they are placed next to each other here. A very important role in the breakdown of the Carboniferous strata play the drilled hole in the Saar 1 151 coal seams. In the Permian, there are, however, rather striking change in the composition of the rock that make a subdivision possible. They allow that the formations can be divided into Subformationen.
- Standenbühl lineup
- Sponheim lineup
- Kreuznach lineup
- Wadern lineup
- Thunder Mountain Formation
- Thallichtenberg lineup
- Upper Church Formation
- Disibodenberg lineup
- Meisenheim lineup
- Lauterecken lineup
- Quirnbach lineup
- Wahnwegen lineup
- Altenglan lineup
- Remigiusberg lineup
The carbon is not treated in this work
- Standenbühl lineup
- Kreuznach lineup
- Wadern lineup
- Thunder Mountain Formation
- Tholey subgroup Thallichtenberg lineup
- Upper Church Formation
- Disibodenberg lineup
- Or home - formation ( are embedded in the upper part of the Lebacher eggs)
- Jeckenbach lineup
- Lauterecken lineup
- Quirnbach lineup
- Wahnwegen lineup
- Altenglan lineup
- Remigiusberg lineup
- Breitenbach Formation
- Heusweiler lineup
- Dilsburg lineup
- Göttelborn lineup ( with the Holzer conglomerate at the base)
- Heiligenwald lineup
- Luis valley formation
- Geisheck lineup
- Sulzbach- formation
- Rothell lineup
- St. Ingbert lineup
- Neunkirchen formation
- Spiesen lineup
Economic Importance
The Saar -Nahe Basin was of great importance for the heavy industry of the Saarland in the past. In the early days of industrialization, there were initially sideritische iron ores of Westfalium, which formed the basis of heavy industry. Later the sideritischen Toneisensteinknollen the Lebacher eggs were smelted (upper part of Odersberg Formation). They justified the existence of the Dillinger Hütte. The Minette ores were smelted then until the 19th century.
The Saar is primarily known by the mining of coal. In the deep drilling Saar 1 a total of 151 coal seams were intersected, which have widths of less than 0.30 up to 2.20 m. Already in the late Middle Ages, the coal mining is documented confirmed. The planned reduction of the coal seams was to start later. However, the reduction amounts were very small and the degradation of the surface. Coal was consumed in the region. 1750/51 nationalized William Henry of Nassau -Saarbrücken all then-existing pits. 1766 were in the Saar coal mines in operation 12: Schwalbach, rod mill, Klarenthal Gersweiler, Rußhütte, Jägersfreude, Friedrich Thal ( Saar), ship Weiler, Wellesweiler, Dudweiler, Sulzbach and Burbach. The coal was now the object of trade and the dismantling volumes increased dramatically.
Fossil deposits
The widespread lake deposits in the Lower Permian of the Saar -Nahe Basin are partly known fossil deposits with fossils in very good condition.