Tectonic Plate

Teory Tectonic Plate (English: Plate Tectonics) is a theory in the field geologilitosfer earth. This theory has been included and also replaces the theory of continental drift first proposed in the first half of the 20th century and concepts of seafloor spreading developed in the 1960s. developed to provide an explanation for the existence of evidence of large-scale movement by
Outermost part of Earth's interior is formed from two layers. At the top there is litosferkerak and the top of the mantle is rigid and solid. Under layers of the lithosphere asthenosphere which there is solid but can flow like a liquid with a very slow and in a geological time scale is very long because of viscosity and shear strength (shear strength) is low. Moreover, the mantle below the asthenosphere is more rigid in character to another. The cause is not a colder temperature, but high pressure. consisting of Lithospheric layer is divided into tectonic plates (tectonic plates). On earth, there are seven major plates and many of the plates which is smaller. This lithospheric plates ride on the asthenosphere. They are moving relative to each other at plate boundaries, both divergent (away), convergent (collide), or transformGempa earth, volcanic activity, mountain formation, and oceanic trench formation generally occur in areas all along the plate boundary. Lateral movement of plate speed is typically 50-100 mm / a. (Sideways). Growth Theory
In the late 19th century and early 20th centuries, geologists assumed that the appearance of the main feature of the earth-based equipment. Most geologic features such as mountains can be explained by vertical crustal movement, as explained in the theory geosinklin. Starting in 1596, has been observed that the Atlantic coast of the face-to-face between the continents of Africa and Europe with North America and South America have similar shapes and seem to never become one. This accuracy will be more obvious if we look at the edges of the continental shelf there. [2] Since then many theories have been advanced for explaining this, but all were at a stalemate because of the assumption that the earth is completely solid trouble finding an appropriate explanation. [3]
The discovery of radium and properties of the heater in 1896 encouraging review age of the earth, [4] as previously estimated by its cooling rate and with the assumption that the Earth's surface radiated like a black body. [5] From these calculations it can be concluded that even if initially the earth is a red-fluorescent objects, the temperature of the Earth will decline to be like now in the several tens of million years. With the newly discovered source of heat is then scientists think it makes sense that the Earth is actually much older and its core is still hot enough to be in a liquid state.
The theory of plate tectonics comes from the hypothesis of continental drift (continental drift) Alfred Wegener proposed the year 1912. [6] and further developed in his book The Origin of Continents and Oceans published in 1915. He proposed that the continents that now there was once a landscape faces were moving away so releasing the continents of the earth's core, such as 'iceberg' of the granite mass of low types that floats above the denser ocean basalt. [7] [8] But without detailed evidence and calculation of the forces involved, this theory is marginalized. Maybe the earth has a solid crust and liquid core, but it still seems unlikely that parts of the crust can be moving. Later, the theory put forward dibuktikanlah British geologist Arthur Holmes in 1920 that links parts of the crust are likely to exist under the sea. Also proved his theory that convection currents in the Earth's mantle is the driving force. [9] [10] [3]
The first evidence that the plates did have a movement direction obtained from the discovery of the difference magnetic field in rocks of different ages. This discovery was first revealed at a symposium in Tasmania in 1956. At first, this invention is inserted into the earth expansion theory [11], but subsequently more precisely leads to the development of plate tectonic theory that explains the expansion (spreading) as a consequence of vertical movement (upwelling) of rock, but avoid the necessity of expanding the size of the earth or expanding (expanding Earth) by entering the subduction zone / hunjaman (subduction zone), and fault translation (translation fault). At that time the theory of plate tectonics changed from a radical theory becomes a theory which is commonly used and then widely accepted among scientists. Further studies on the relationship between seafloor spreading and magnetic field reversal (geomagnetic reversal) by geologist Harry Hammond Hess and Ron G. oseanograf Mason [12] [13] [14] [15] showed the exact mechanisms that explain the vertical movement of the new rock
Along with the receipt of the earth's magnetic anomaly indicated by lane-lane parallel to the symmetry with the same magnetization in the bottom of the sea on both sides of the mid-oceanic ridge, plate tectonics became widely accepted. Rapid advances in seismic imaging techniques initially in and around Wadati-Benioff zone and various other geologic observations soon confirmed as the theory of plate tectonics that have exceptional ability in terms of explanation and prediction.
Research on the seabed, a branch of the rapidly growing marine geology in the 1960s played an important role in the development of this theory. Correspondingly, plate tectonic theory was also developed in the late 1960s and have been pretty universally accepted in all disciplines, as well as renewing the earth science world by giving an explanation for the wide range of geological phenomena and their implications in other fields such as paleogeographic and paleobiology Key principles
The outside of the Earth's interior is divided into lithosphere and asthenosphere based on differences in the way of mechanical and heat transfer. More cold and rigid lithosphere, while the asthenosphere is hotter and mechanically weaker. In addition, the lithosphere loses heat by conduction, while the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. This division is very different from the distribution of the earth chemically into core, mantle, and crust. Lithosphere includes the crust and also own part of the mantle. A part of a coat can become part of the lithosphere or the asthenosphere at different times, depending on the temperature, pressure, shear strength. Key principle of plate tectonics is that the lithospheric plates separate into different tectonic. These plates move ride on the asthenosphere that has viskoelastisitas so is like a fluid. Plate movement can usually reach 10-40 mm / a (as fast as a fingernail growth) such as the Mid-Atlantic Ridge, or reaches 160 mm / a (as fast hair growth), such as the Nazca Plate. [16] [17] These plates thickness of about 100 km and consists of the upper mantle litosferik the carpet is coated with one of two types of crustal material. The first is the oceanic crust or often called a "sima", a combination of silicon and magnesium. The second type of continental crust that is often called "bad luck", a combination of silicon and aluminum. Both types of crust thickness is different in terms of where the continental crust has a thickness that is much higher than the oceanic crust. Continental crustal thickness reaches 30-50 km, while oceanic crust is only 5-10 km.
Two plates will meet along the plate boundary (plate boundary), ie areas where geological activity like earthquakes generally occur and the formation of topographic feature such as mountains, volcanoes and oceanic trenches. Most active volcanoes in the world was on the plate boundaries, such as the Pacific Ring of Fire (Pacific Ring of Fire) on the Pacific Plate is the most active and widely known.
Plate tectonics may be a continental or oceanic crust, but usually one plate consists of both. For example, the African Plate includes the continent itself and most basic Atlantic and Indian Ocean. The difference between continental and oceanic crust is based on the density of material. Oceanic crust is denser than continental crust due to differences in the comparison of the various elements, especially silicon. Oceanic crust is denser because compositions which contain less silicon and more heavy material. In this case, the oceanic crust is more mafikfelsik said. [18] Thus, the oceanic crust is generally located below sea level like most of the Pacific Plate, whereas continental crust occur over the sea surface, following a principle known as isostasi. The types of plate boundaries Three types of plate boundaries (plate boundary). 

There are three types of plate boundaries that are different from the way the plates move relative to one another. These three types each associated with different phenomena on the surface. Three types of plate boundaries are:

   1. Limits transforms (transform boundaries) occurs when plates move and experiencing friction with each other laterally along the transform fault zone (transform fault). Relative movement of the two plates can be sinistral (left on the side opposite the observer) or dextral (to the right on the side opposite the observer). Examples of this type of fault is the San Andreas Fault in California.
   2. Divergent boundary / Constructive (divergent / constructive boundaries) occurs when two plates move away from each other. Mid-oceanic ridge and fracture zones (rifting) enabled is an example of a divergent boundary
   3. Convergent Boundaries / destructive (convergent / destructive boundaries) occurs when two plates rub against each other approached to form a subduction zone if one plate moves under another, or continent collision (continental collision) if the two plates contain continental crust. Deep sea trench, usually located in the subduction zone, where the pieces of plate which contains a lot of character terhunjam hydrate (containing water), so that the content of this water is released when the warming occurs mixed with the mantle and cause melting, causing volcanic activity. Examples of this case we can see in the Andes Mountains in South America and the island arc of Japan (Japanese island arc).