Our planet is a cosmic body, which has heoyid form and the surface with approximately 510 million km². As a result of the differentiation of the Earths matter, the division into geospheres has happened. The object of geotectonic study is lithosphere, which includes the Earth’s crust, and is usually the top layer of the mantle up to ten kilometers. The total capacity of the lithosphere varies from 5-25 km in mid-ocean ridges, volcanic arcs and continental rift zones. 100-200 km is on the periphery of oceans, continents and, in particular, on the ancient shield platforms. The lithosphere development is influenced by the endogenous and exogenous processes, such as tectonic, magmatic, metamorphic, accumulation, and nutrient (Hess 388-390)
The major structural units of the lithosphere plates are limited areas of the maximum tectonic, seismic and volcanic activity. The largest of them are Eurasian, American, African, Pacific, and Antarctic Indo-Australian. According to the theory of the tectonic plates, the plates under the influence of convection move with speed from the 1 millimeter to 10-20 cm per year. This move causes the destruction and the rupture of the continental blocks in the tension areas, their horizontal displacement and the young crust formation in the bed of newly formed oceans; accumulation, accompanied by thrust, folding and mountains forming – in the areas of compression. There are two main types of crust: continental and oceanic, which differ in their composition, structure and capacity. The continental crust is formed of three types of layers: sedimentary, granitic and basaltic. In the oceanic crust, the power which usually does not exceed 10.2 km, granite layer is absent (Carey 176).
The continents are large amounts of the continental crust type, much of which appears above the surface of the oceans, and peripherals are offshore zone and the continental slope. There are 6 continents: Eurasia, Africa, North America, South America, Australia and Antarctica, but in previous geological epochs their number was markedly lower, up to a single continental block Pangea, which was divided initially on Laurasia and Gondwana, further fragmentation and subsequently given the current configuration of the world. The main ancient platforms are Eastern European, Siberian, Sino-Korean, Arabian and Eurasian, African, Australian, Antarctic, North American, South American – on the respective continents. Platform cover is usually labor bedding, power up to 5 km, which increases in flat cup-shaped depressions or Syncline and decreases in the same flat elevations – anticline (Hess 377-380).
Synclines can be formed over the central parts of the panels (Syncline Hudson Bay in the Canadian Shield, of Bothnia in the Baltic) over peripheral (Caspian syncline in southern Russian platform), or joints is a special type Syncline gangway type Tunguska on the Siberian platform or Parana on American platform, with powerful basalts’ cover. Anticlines examples are Voronezh and Belarus to the Russian platform Anabas on the Siberian, Central Kansas, Nashvil-Tsyntsinati in North American. Specific types of platform structures are avlakogens that constitute intra-platform mobile linear zone. Usually it is deep (5-10 km), narrow (10-100 km) and elongated to 1000 km deflection, limited faults. In the present structure they look like narrow linear fold zones (Danish-Polish avlakogene) or Wide-Syncline basins, or a combination of linear deflections-graven and uplift, a handful (zone Vihyta North American platform). Provision is also less structural forms such as granite domes of old boards and bodies, boards of various ages’ consolidation deflections or depressions, vaults or performances, shafts, etc (Carey 204).
Moving (folded) zones are the next global structural element of the crust. This large (hundreds of kilometers), very extended (up to thousand kilometers) long zones, where the manifest intensive processes of tectonics, folding, magmatism are of different ages (White& McKenzie). They lay confined to the boundaries of lithosphere plates. The largest are the Mongol-Okhotsk, Mediterranean-Himalayan and Pacific mobile zones. Within the mobile zones stand folded regions and systems that differ in composition, structure and age of consolidation. Age folded areas, usually correlate with age, the last phase of folding: Baikal, Caledonian, Hercian, Cimmerian, Alpine and their analogues on different continents. Development of a mobile zone is characterized by repeated changes of the tectonic regimes, and periods of cyclical stretching of the horizontal compression. These processes are accompanied by complex multiple folding, the thrust and tectonic cover, considerable horizontal movement of crustal blocks and progeny. Along the platforms borders is the edge of the foothills bending, and in the rear mountain systems – the intermountain basins, which are filled with the products of erosion of the newly established mining facilities. Rift zones are formed from the transverse faults of the displaced segments on the mechanism of displacement to a distance of several tens to hundreds of kilometers. Typically, they correspond to the deep (5 km) gorge, which divide the ocean bed and slopes of underwater ridges. Probably in the axial rift of the mid-ocean areas due to the movements of the tectonic plates forms the new oceanic crust. The speed of the plate’s movement reaches from 2 to 18 cm / year (Hess 366-370). Thus, our planet is the only geological object that lives on the system of natural laws. Its main structural elements are in constant interaction of the complex, changing, and moving.
Bibliography
Carey, S. Warren. The tectonic approach to continental drift. In Carey, S.W..Continental Drift—A symposium, held in 1956. Hobart: Univ. of Tasmania. pp. 177–363. 1958. Print
Hess, Darrel. Mac Kings Physical Georaphy. 10th edition. P.377-390.2009. Print
White, Richard and D. McKenzie,. Magmatism at rift zones: The generation of volcanic continental margins and flood basalts. Journal of Geophysical Research. 1989.Print