Tectonic structure of continents
Tectonic structure of continents
A. the continent consists of two main structural elements — Waandishi Vostok platform and folded mountain belt of the Andes
Waandishi platform include Precambrian East SA and epihercynian platform (epibionts) Patagonian plate
The Foundation of the South American platform consists of uneven-aged blocks, consolidated during the period of the upper Proterozoic-early Paleozoic.
The largest of the protrusions of the Foundation — Guiana, Western Brazil and Eastern Brazilian shields;
West Guiana and Brazilian shields almost entirely of glubokoeshelonirovannoj and intensely deformed rocks of the Archean and lower Proterozoic (gneisses, crystalline schists and granites).
The Eastern Brazilian shield consists of separate blocks of early Precambrian – banality (Serra dospinescu, Chapada Diamantina, etc.)
On the Western Guiana and Brazilian shields have survived composing the watershed areas of outcrops of ancient, protoplectron cover, composed of red clastic strata and layers of basalts; in terrain they correspond to tepui and Chapada
Younger case (middle — upper Paleozoic and Mesozoic) performs syneclise platform. Social the inhomogeneous case. In the late Carboniferous — early Perm territory to the South of the Amazon was covered by a cover glaciation. (Perm-Carbuncle glaciation). The warming climate led to the change of glacial deposits (tillites) coal (lower Permian), and then arid — mostly Sandstone (upper Permian— Cretaceous).
Major basin 5: Amazon, Redtail, Maranhao, são Francisco, paraná.
Amazon, Redtail syneclise and San Francisco were incorporated in the lower Paleozoic of the Amazon – along a major fault zone that separated the Guiana and Brazilian shields. Syneclise Maragato (Paranaiba) and paraná were formed in the upper Paleozoic, resulting in the band of meridional strike valleys separated the Eastern Brazilian shield of Western Brazil;
In the basin of the paraná traps are widely developed mainly early Cretaceous age.
The southern part of the South American platform — Patagonian plate — different younger Paleozoic basement; usually considered as an independent structural unit consisting of two uplifts — Northern Patagonia and southern Patagonia (Deseado and Santa Cruz) and two deflections: Neuquen — San Matias, Chubut and San Jorge.
The Andes are one of the world’s largest mountain systems age they relate to the field of Hercynian and Alpine folding.
Tectonic movement, accompanied by seismic and volcanic activity continue in our time. This is because along the Pacific coast of South America is a subduction zone: plate Nazca and Antarctic disappearing under the South American, which contributes to the development of the processes of mountain building. The extreme southern part of South America, Tierra del Fuego, separated by a transform fault from the small Scotia plate. For the Drake passage continues the Andes mountains of the Antarctic Peninsula.
Located on the S. Coast ranges of Venezuela latitudinal extent amount of the southern flank of the Antillean arc; composed mostly in meso-Cenozoic.
Tectonic structure of North America
The North American plate containing the continent of North America, the North-Western part of the Atlantic ocean, and about half of the Arctic ocean
with the South limited the Cayman transform faults and Barracuda.
The Western border of the plate is mainly represented by extensive subduction zone, which is absorbed by the oceanic crust of the Pacific plate and plate Juan de Fuca.
The Eastern boundary of plates runs along the Mid-Atlantic ridge, and the North – to the Arctic by its continuation – the axis of the Gakkel ridge.
Some researchers attribute to the North American plate Alaska and Chukotka, however, is more rightful to include these areas in consisting of many small plates of the Circum – Pacific belt of planetary compression of the lithosphere.
Area shifts the tectonic plates of Juan de Fuca.
Central, most of S. A. is Precambrian North American platform (including Greenland without its Northern and North-Eastern suburbs)
Platform edges folded mountain structures of the Caledonian (North-East of the country, Greenland, the island of Newfoundland, Northern Appalachians), Hercynian (Southern Appalachians, the Ouachita mountain range and its buried continuation of the Canadian Arctic archipelago), the Mesozoic-Cenozoic (Cordillera) of age.
Prymeksykanskiy and Atlantic coastal lowlands in the USA covered with a cover of Mesozoic-Cenozoic sediments and are slabs platform with Paleozoic basement.
The Foundation of the North American platform is exposed to S. the USA, in Canada, in the South of the Canadian Arctic archipelago and along the Western and South-Eastern coasts of Greenland, forming the Canadian shield. It is composed of mainly granite gneiss of Archean and early Proterozoic age. In the South-Eastern part of the shield extends Grenville belt, composed of early Precambrian rocks, reworked during the late Proterozoic
The sedimentary cover of the platform composes of a Central plate (Midcontinent) and the Great plains. The case is of Midcontinent Ordovician-Carboniferous, and on V. and Permian age; the case of the Great plains also includes deposits of Mesozoic and Cenozoic continental. To change the depth of the Foundation is allocated a number of large depressions — the syneclise (the depth of 3-4 km) and vaults is the ANTECLISE; the South-Western part of the dissected rolling Ouachita mountains area of North-West strike.
The most ancient element of the folded framing of the North-American platform — the caledonides of northeastern Greenland, the thick layer of folded rocks to the top.Precambrian and lower Paleozoic, intensively deformed and slipped over in the form of tectonic sheets at the edge of the platform
From the South-East of the edge of the platform flanked by Paleozoic folded system of the Appalachians and the island of Newfoundland (Caledonian and Hercynian to S. Y.). Northern Appalachian fold system and the island of Newfoundland is bordered by the Canadian shield along the fault (the Logan line).
In both North and South in the Appalachian mountains there are narrow grabens with continental sediments and basaltic lavas of the upper Triassic — Jurassic bottom, representing the result of the disintegration of the Appalachian system before joining the platform development stage.
From the Atlantic ocean and the Gulf of Mexico (within coastal lowlands) SBV sides of the Atlantic ocean and the Gulf of Mexico (within coastal lowlands) zone Hercynian folding covered with a thick layer of Cretaceous and Cenozoic sediments. Hercynian (indiska) fold system of the Canadian Arctic archipelago and Northern Greenland is composed of predominantly terrigenous-carbonate sediments of Cambrian — Devonian, in wrinkled folds at the head of carbon. In the area of O. Sverdrup and adjacent Islands on the Paleozoic folded base imposed a large and deep depression Sverdrup, made terrigenous platform deposits of the upper Paleozoic and the Mesozoic, the breached salt domes (salt upper Paleozoic age) that are associated with gas deposits.
From the Atlantic ocean and the Gulf of Mexico (within the Coastal lowlands) zone Hercynian folding milevichi covered by thick Cenozoic sediments. Hercynian (indiska) fold system of the Canadian Arctic archipelago and Northern Greenland is composed of predominantly terrigenous-carbonate sediments of Cambrian — Devonian, in wrinkled folds at the head of carbon. Along the Pacific coast extends S. A. Cordillera fold belt V. which is almost everywhere bordered with the North American platform and only in Alaska is limited by a system of ridge Brooks, a member of Initsky belt;
in the South the Cordillera interfaced with the structures of the Antillean-Caribbean region.
Within the Cordillera belt sladkogolosaya proceeded in three phases nevadica, laramide orogeny and Alpine folding