Rift

Under grave breach (including rift, Rift Valley Rift of Engl. Tear, column) is understood in the geology of an elongated tectonic elongation zone, in which a relatively narrow range crust along deep-seated faults in the crust descends. The distortions may already have been present, but may be new also arose due to the tensile forces. Active grave breaches [note 1] are also simultaneously sedimentary basins.

Formation

Grave breaches occur when the continental crust is stretched by various causes. Like any relatively brittle material can break the crust and yield under this tension.

Continental rifting

In continental rift zones can be, on the basis of the dynamic processes that lead to their formation, in passive and active Rifts Rifts [note 1] differ.

In the case of a passive rifts a crustal field responds to tectonic forces, mostly from plate tectonic processes in the vicinity, eg a mountain building, go out. This resulted, for example, the Upper Rhine Graben due west -east directed elongation transverse to the northward compression of the Alps arise.

Active Rifts emerge over Manteldiapiren (English: mantle plumes ) in so-called hot spots of thinned lithosphere. It comes through the rise of streams of hot mantle material at the hot spot to a heating of the lithosphere from below, making these raised thermally spacious, slowly melted and is thinned out, such as the Rift Valley.

Both active and passive rifts it usually comes to the formation of relatively narrow grave grave systems with high shoulders. Typical of the grave structures relatively flat-lying earthquake epicenters and often an extensive, bimodal volcanism are thus both basic and felsic volcanism with shield and column volcanoes. Grave breaches are the only large tectonic environment in which there is karbonatitischem volcanism, such as in the case of the Emperor chair or Ol Doinyo Lengai. By lowering the crust the grave center can drop below sea level and are then flooded by the sea. Thus, for example, find in the Upper Rhine Graben and the associated Mainz Basin fossil- rich marine sediments from the Oligocene and Miocene. If the rift zone far inside of the continent is more likely to form a lake, or a lake landscape there.

If there is continuous active rifting crustal strain can no longer be compensated by the decrease of continental crustal blocks and the Riftvulkanismus produced along the axis grave new, basaltic ( oceanic ) crust. A continental rifting goes up for a mid-ocean ridges on between two divergent tectonic plates.

Postorogene trenches

Lithosphere was thickened, heated and shattered by a mountain formation, tends when the tectonic kompressionale pressure is off to sag under their own weight. This results in the interior of the rock pool and grave structures, such as today in the so-called Basin -and- Range province in the southern Rocky Mountains. Something similar happened in the Upper Carboniferous and Permian, about 300 million years in the Variscan mountain range in Central Europe.

Examples of rift zones of the earth

Active Rifts (meaning triggered by Manteldiapire )

• The Great African grave breach ( Great Rift Valley) extends from Lebanon to Mozambique and is caused by the drifting apart of the African, the Arabian Plate and the Somali Plate. The East African rift is part of the Great African grave breach. Between African and begriffener in formation Somali plates the extensional tectonics has led to increased volcanism along the grave zone in a length of 5000 km and one partial sinking of the trenches below the level of the sea. In the next 10 to 20 million years ago is to be expected with the advance of the Red Sea in this grave breach and a further drifting apart of East and West Africa.

Passive Rifts

• The Upper Rhine Valley in southwest Germany, bounded by the Vosges and the Palatinate Forest in the west and the Black Forest and Odenwald in the east.
• The Elbe- zone between the Erzgebirge desk plaice in the southwest and the Lusatian plate in the northeast
• The Egergraben between Erzgebirgscholle in the northwest and Bohemian mass (including Kaiserwald ) in the southeast
• The Oslo Graben in southern Norway, situated in the southern part of the Oslo fjord. This grave structure is inactive for several 100 million years.