Plate Tectonic

Plate tectonic theory

The concept of plate tectonic has make established   ground in explaining many important problem of physical geology including mountain building, folding, faulting, seismicity, volcanism etc. The  theory of plate tectonic developed by Geo scientist during 1960s is described as a most revolutionary concept in the history of geology. The term plate was first used by J.T. Wilson in  1965  and result of continental drift theory of Wegener.  according to this concept the rigid lithospheric slabs or block and solid crystal plates are  called plate. The whole mechanism of evolution, nature and the motion of plates is known as plate tectonics. The rigid lithosphere is capable to moving bodily over the Asthenosphere( hot-plastic flexible layer of upper Mantle). There are  six major  and  20  minor plates  have been identified .About twelve of these plates have been so far distinguish and the name of twelve major and minor lithospheric plates under focus to study of Geoscientist e.g.

• The Pacific plate,
• The North American plate,
• The South American plate,
• The African plate,
• The Antarctic plate,
• The Indian Australian plate the European plate,
• The Arabian plate,
• The nazea plate,
• The Caribbean plate,
• The scotia plate and
• The Philippines plate.

 

  Plate tectonic theory is based in two major concepts

 (a)  The concept of continental drift   and

 (b) Concept of sea-floor-spreading.

The main ideas underline the theory of plate tectonics are the out-come to the   study   of the structure of the ocean-floor and the formation of young oceanic-crust in  mid oceanic ridge.  

 Chemical composition of interior

Inner part        Fe, Ni

Outer part       Fe, Ni + silica

Mental.           Olivine                                                       

Oceans.           Basalt

Mental.           Granite and Andesite 

Location of the rock	example	Properties	Reaction (if we melting)
Mental	Olivine	Highly heaviest fluid	Mercury
Oceanic crust	Basalt	Less heavier fluid	Water
Contcrustal crust	Andesite	Less mobile light fluid	Honey
Continental crust	Granite	Least mobile lightest fluid	Wax

 

 Movement  of  Plates

Plates	Divergent boundaries	Convergent boundaries	Transform boundaries
Similar Names	Constructive plate margin or accreting plate margin	Destructive plate margin  or consuming plate margin	Shear plate margin or conservative plate margin
Cause	Ascending Limb of convection current beneath the earth's crust	Descending Limb of convection current beneath the earth's crust	Horizontal movement of convection current beneath the earth's crust
Mechanism	Two plates are in the motion away from each other	Two plates are in the motion towards each other	Two plates are slide apart each other
Formation	Mid -oceanic -ridge, rift valley, shallow focus earthquakes and volcanic eruption	Mountains formation and major earthquakes	Fault create and shallow focus earthquakes with horizontal slips
Examples	North America plate Vs  Eurasian plate	Indian plate and Tibetan plate	San-Andres Fault