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Helvetic Nappes
{{Unreferenced, date=June 2019, bot=noref (GreenC bot) The Helvetic nappes (german: Helvetische Decken) are a series of nappes in the Northern part of the Alps and part of the Helvetic zone. They consist of Mesozoic limestones, shales and marls that were originally deposited on the southern continental margin of the European continent. During the Alpine orogeny they were thrust north over a décollement and at the same time were internally deformed by folding and thrusting. Tectonic location The Helvetic nappes are thrust over the Infrahelvetic complex and the external massifs of the Alps (like the Aarmassif or Mont Blanc Massif). In Switzerland, Germany and Austria they are also thrust over the Molasse basin of the Alpine foreland. In turn, the Helvetic nappes were overthrust by the Penninic nappes from the south. In Switzerland these have been eroded away at most places but in Germany and Austria they are still covering the Helvetic nappes. Due to this the Helvetic nappes only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nappe
In geology, a nappe or thrust sheet is a large sheetlike body of rock (geology), rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones. Nappes form when a mass of rock is forced (or thrust fault, "thrust") over another rock mass, typically on a low angle fault plane. The resulting structure may include large-scale recumbent Fold (geology), folds, shearing along the fault plane,Twiss, Robert J. and Eldridge M. Moores, ''Structural Geology,'' W. H. Freeman, 1992, p. 236 Thrust fault#Thrust duplex, imbricate thrust stacks, Window (geology), fensters and klippes. The term stems from the French word for ''tablecloth'' in allusion to a rumpled tablecloth being pushed across a table. History Nappes or nappe belts are a major feature of the European Geology of the Alps, Alps, Dinaric Alps, Dinarides, Carpathians and S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molasse Basin
The Molasse basin (or North Alpine foreland basin) is a foreland basin north of the Alps which formed during the Oligocene and Miocene epochs. The basin formed as a result of the flexure of the European plate under the weight of the orogenic wedge of the Alps that was forming to the south. In geology, the name "molasse basin" is sometimes also used in a general sense for a synorogenic (formed contemporaneously with the orogen) foreland basin of the type north of the Alps. The basin is the type locality of molasse, a sedimentary sequence of conglomerates and sandstones, material that was removed from the developing mountain chain by erosion and denudation, that is typical for foreland basins. Geographic location The Molasse basin stretches over 1000 kilometers along the long axis of the Alps, in France, Switzerland, Germany and Austria. The west end is at Lake Geneva, where the basin's outcrop is just 20 km wide. Further to the northeast the basin becomes wider. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jura Mountains
The Jura Mountains ( , , , ; french: Massif du Jura; german: Juragebirge; it, Massiccio del Giura, rm, Montagnas da Jura) are a sub-alpine mountain range a short distance north of the Western Alps and mainly demarcate a long part of the French–Swiss border. While the Jura range proper (" folded Jura", ''Faltenjura'') is located in France and Switzerland, the range continues as the Table Jura ("not folded Jura", ''Tafeljura'') northeastwards through northern Switzerland and Germany. Name The mountain range gives its name to the French department of Jura, the Swiss Canton of Jura, the Jurassic period of the geologic timescale, and the Montes Jura of the Moon. It is first attested as ''mons Iura'' in book one of Julius Caesar's ''Commentarii de Bello Gallico''. Strabo uses a Greek masculine form ''ὁ Ἰόρας'' ("through the Jura mountains", ''διὰ τοῦ Ἰόρα ὄρους'') in his ''Geographica'' (4.6.11). Based on suggestions by Ferdinand de Saussure, early c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Facies
In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formation), and the changes that may occur in those attributes over a geographic area. A facies encompasses all of the characteristics of a rock including its chemical, physical, and biological features that distinguish it from adjacent rock. The term facies was introduced by the Swiss geologist Amanz Gressly in 1838 and was part of his significant contribution to the foundations of modern stratigraphy, which replaced the earlier notions of Neptunism. Types of facies Sedimentary facies Ideally, a sedimentary facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment. Sedimentary facies are either descriptive or interpretative. Sedimentary facies are bodies of sediment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apulian Plate
The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African Plate along a large transform fault in the Cretaceous period. The name Adriatic Plate is usually used when referring to the northern part of the plate. This part of the plate was deformed during the Alpine orogeny, when the Adriatic/Apulian Plate collided with the Eurasian Plate. The Adriatic/Apulian Plate is thought to still move independently of the Eurasian Plate in NNE direction with a small component of counter-clockwise rotation. The fault zone that separates the two is the Periadriatic Seam that runs through the Alps. Studies indicate that in addition to deforming, the Eurasian continental crust has actually subducted to some extent below the Adriatic/Apulian Plate, an unusual circumstance in plate tectonics. Oceanic crust of the African Plate is also subducting under the Adriatic/Apulian Plate off the western and southern coasts of the Italia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries. Subduction is possible because the cold oceanic lithosphere is slightly denser than the underlying asthenosphere, the hot, ductile layer in the upper mantle underlying the cold, rigid lithosphere. Once initiated, stable subduction is driven mostly by the negative buoyancy of the de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Boundary
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more Plate tectonics, lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, Orogeny, orogenesis, destruction of lithosphere, and Deformation (geology), deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by the radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valais Ocean
The Valais Ocean is a subducted oceanic basin which was situated between the continent Europe and the microcontinent Iberia or so called Briançonnais microcontinent. Remnants of the Valais ocean are found in the western Alps and in tectonic windows of the eastern Alps and are mapped as the so-called "north Penninic" nappes. Tectonic history After the breakup of Pangaea in the early Mesozoic age, the continents of Africa, South America, Europe and North America began to move away from each other. The breaking up, or rifting, did not take place along one unbroken line; thus, at the southern edge of the European plate the microcontinent Iberia also began to break away from Europe. In the western part of the rift that separated the two landmasses, oceanic crust was formed in what is at present the Gulf of Biscay, while in the eastern part the Valais Ocean was formed. When in the Cretaceous period Africa again began to move towards Europe, the Valais Ocean became sandwiched between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur as dissolved minerals precipitate from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Limestone Alps
The Northern Limestone Alps (german: Nördliche Kalkalpen), also called the Northern Calcareous Alps, are the ranges of the Eastern Alps north of the Central Eastern Alps located in Austria and the adjacent Bavarian lands of southeastern Germany. The distinction from the latter group, where the higher peaks are located, is based on differences in geological composition. Geography If viewed on a west–east axis, the Northern Limestone Alps extend from the Rhine valley and the Bregenz Forest in Vorarlberg, Austria in the west extending along the border between the German federal-state of Bavaria and Austrian Tyrol, through Salzburg, Upper Austria, Styria and Lower Austria and finally ending at the Wienerwald at the city-limits of Vienna in the east. The highest peaks in the Northern Limestone Alps are the Parseierspitze () in the Lechtal Alps,Reynolds, Kev (2010). ''Walking in the Alps'', Cicerone, . and the Hoher Dachstein (). Other notable peaks in this range include the Zugs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical erosion procee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
