Hanau-Seligenstadt Basin

The Hanau- Seligenstädter sink ( natural area 232.2 ) is a marginal basin of the Upper Rhine Graben area of the eastern Lower Main level (main unit 232 ), which is also referred to interchangeably Eastern Lower Main level.

Location

The Hanau- Seligenstädter Valley is located in the territory of the eastern Lower Main level. The river Main flows through it between Aschaffenburg and Offenbach am Main. Due to its location in the eastern Rhine -Main area, the Hanau- Seligenstädter valley is densely populated. The largest cities include Hanau, Blessed city and Dieburg.

Geological structure

The Hanau- Seligenstädter Valley is a känozoisches, grave -like basin. As a side basin of the Upper Rhine Graben is part of the European Cenozoic rift system they, a fracture zone that runs through Europe from the North Sea to the Mediterranean.

In the West, a Horst ( Horst Sprendlinger, Frankfurt in the northern extension Horst ) separates the Hanau- Seligenstädter Valley from the Upper Rhine Graben. The eastern shoulder grave forms of the Spessart. In the south, the valley is bordered by the Odenwald. In the north the grave shoulders run like a wedge together. The ground below the pelvic deposits is set up from the Variscan basement of the Central German Crystalline Zone and the discordant auflagernden layer sequence from the Permian (Upper Rotliegend ) to the lower Triassic ( Buntsandstein ). The deposited layers in the basin reach more than 280 m thick and range from the Oligocene to the Quaternary. Oligocene and Miocene prevail in marine, brackish and freshwater before, last continental clays, marl, limestone beds and sands with intercalated basaltic. The alluvial deposits of the Pliocene and Quaternary consist of sand, gravel, silt and clay, also in the Pliocene lignite. The surface is marked by a river terrace landscape.

Genesis

Since the Triassic to the early Paleogene was the territory of the present - Hanau Seligenstädter Valley depositional environment but no ablation area. The decrease started later than in the Oligocene ( Rupelium ) to around 30 million years ago during the formation of the Upper Rhine Graben. The Upper Rhine grave sea or the Oberrheingrabensee stretched out well beyond the field of Hanau- Seligenstädter sink. From the pool edges registered rubble during the Miocene led increasingly to the silt of the lake. The Hanau- Seligenstädter Valley became a river plain. Before around 15 million years ago during the Langhiums volcanoes lava flows over parts of the area, have solidified as a basalt rock. Even during the Langhiums began the rivers of removing their own debris again. It was not until the Pliocene ( about 5 million years ago ) pitched the Lower Main River and its tributaries in their valleys again sand, gravel and clay from. In lakes and moors, peat and clay layers formed (now lignite). The then relatively short Main tapped in the early Quaternary of the Upper Main. The thereby greatly increasing flow transported large quantities of sand and gravel in the Hanau- Seligenstädter sink. In the Middle Pleistocene rivers eventually started again, to dig into their older deposits. The various stages of this Eingrabungsgeschichte have been preserved in the form of river terraces.

Raw materials and groundwater

In the Hanau- Seligenstädter sink is obtained in numerous pits and quarry sand, gravel and clay. Until the 1930s Kahl am Main and Blessed city Pliocene lignites were in the region around Großkrotzenburg degraded. The open-cast mines today form the Bald Lake District. In the vicinity of Hanau some disused quarries evidence (eg the Dietesheimer quarries ) from the extraction of Miocene basalts to the 1980s. The sands and gravels are abundant aquifers are used for water supply.