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Monday, October 29, 2018

Convection Current



Convection  Current


Convection current condition in the mantle zone seems to cause Plate motion. This is thought to be  slow displacement or Convection of a mental material under the action of temperature difference between its floor and the roof. As the rocks are heated deep in the earth they become less dance and rise to spreading ridges. As the rocks move litelitera,  they cool, becoming dense enough to sink at subduction zones.

Image result for convection current theory 

A Convection Current is a process which involves the movement of energy from one place to another and the meaning of Convection is "heat transfer". It is also called to as convection heat transfer.Heat energy can transfer by convection when there is a significant difference in temperature between two parts of a fluid. When this temperature difference exists, hot fluids rise and cold fluids sink. Convection that occurs naturally is called natural convection or free convection. If a fluid is circulated using a fan or a pump, it's called forced convection. The cell formed by convection currents is called a convection cell.

Convection Current Hypothesis


Image result for convection current theoryThe hypothesis suggests that the mountain range were initiated and developed due to the convection currents supported to the exist in the plastic - type mental blow the crust of the earth. The origin of the currents may be due to very hot liquid core of the Earth. Some phenomena of convection currents are given below :

  • Convection currents  travel horizontally under the crust of the Earth.
  • In the journey of convection currents, they pull along the light material of the continental margins and in the process themselves become cold and heavy.
  • Thus,  two types of convection currents come into play forming almost cycle:  first - the ascending currents of light and hot material, and second the descending current of heavy and a cold material.
  • In the Divergent plate boundaries, if the Ascending  rising limb of convection current beneath the earth's crust volcanic arc were formed.
  •  In the  convergent plate boundaries,  if the descending limb of convection current beneath the earth's crust mountain building were formed.
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Plate Tectonic Theory

Movements of Plates


 
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Types of Plate movement

Movements of Plates


Plate Tectonic theory is in the type of drift, with respect to the adjoining plates along the plate boundaries.
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H.Hess produced the concept of plate tectonic in 1960 in support of continental drift.  All the activities  occur along the plate margin e.g. seismic events, volcanicity, mountain building, folding, faulting etc. Plate margin are generally divided into three main groups as follows
  1. Constructive plate boundaries

  2. Destructive plate boundaries

  3. Conservative plate boundaries

     

Constructive Plate Boundaries

Constructive plate boundaries are also called is divergent plate boundary or accreting plate boundaries. This is a zone along with two plates are in the motion away from each other as a result of fisher developers, and create new margin. Infect oceanic plates split apart along the mid oceanic ridge and move in the opposite direction. The fissure represents the zone of spreading and created new crust by upwelling of material from the mental. It is the best example seen in the case of the North American plate versus Eurasian plate. Eurasian plate is moving away towards south east whereas North American plate  is drifting towards south west.

Image result for constructive plate boundaries diagram

 Oceanic Divergent

The divergent plate boundary on the ocean floor is marked by the crust of the mid oceanic ridge. The existence of the Rift Valley at the ridge  crest, associated with Basaltic lava. Volcanism appears to be the result of the ocean divergent. Eruption of the Lava creates new ocean floor within the Rift Valley.
Image result for oceanic divergent boundary


Continental divergent
This is also known as continental ruptures and causes elevations of continent,this column of hot molten rock is called mantle plume. Due to elevation the crust becomes thinner above the uplift and the tensional force cause the plate to fracture forming a rift valley along a central graben.
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The volcanic country Iceland is a island located in the MID ATLANTIC RIDGE
Its believed that the mid Atlantic ridge which forms a major part of the sub oceanic ridge encircling to the globe from Arctic ocean to South Africa. This type of presses is sometimes also referred as sea floor spreading.
some scientist have postulated development of new spreading centers under the African plate along the East African rift zone.

Destructive Plate Boundaries


Image result for Destructive plate BoundariesDestructive plate Boundaries are also called as convergent plate or consuming plate boundaries because two plates move towards each others and leading edge of one plate overrides the other plate and the overridden plate is subducted  into the mantle and thus part of the is lost in mantle.There can be three types of situations as
  1. Ocean -ocean  convergence
  2. Continent-continent convergence
  3. Ocean -continent convergence


Ocean -Ocean  Convergence

Image result for Ocean -Ocean  Convergence PLATETwo oceanic crusts converge and one plate bends down ward beneath the other. This phenomenon is called Subduction. Subduction of plate forming the oceanic crust is cause of the trench which is formed immediately over the zone of subduction.the magma bodies rise slowly to the surface forming a curved line of volcanoes which form a string of volcanic island  knows as island arc.
Examples: The deepest Trench is located at the southern ssubduction end of the Mariana Trench caused by the convergence of Pacific plate.



Ocean-Continent Convergence
A plate containing the oceanic crust is subducted  under the continental crust because it's less dence comparitivily oceanic crust. Magma that rises from the subduction zone and forms  a Volcanic arc. But the continental crust remains intact and with the upward rising of hot magma from  the subduction zone becomes thicker and formed a  young mountain range.
  • Image result for trench FORMATIONThe Peru Chile trench developed of the South America coast line is described as a typical example of subtraction.

    Image result for Andes mountain FORMATION
  • The South America Continental plate supporting the high range of Andes mountain is considered a proof enough for this typical case.


 


Continental -Continental Convergence

Image result for Continental -Continental Convergent PLATETwo continents move towards each others and the leading edge of the both plates are composed of Continental rock, it is more difficult for subtraction to start. in this case a continental collision boundary may develop, in which the edges of the plates crumpled into mountains. this type of  convergent boundary condition has produced some of the highest linear mountain system on the earth, such as Alpine in Himalayan mountain belts.


Conservative Plate Boundaries


These  are also called as share plate margin and transform boundaries or transform fault. Here  two plates pass or slide past one another along transform faults and this crust is neither created or destroyed. most such boundaries occur in Oceanic crust but some occur on continents are well known Continental transform boundary is the
Image result for San Andreas fault
San Anderson fault in California Where are segment of the Pacific plate is sliding horizontally past assignment of North American plate

 

 

 

Mineralization along different Boundaries

Deposit at Convergent Boundaries

  • Deposits(Zn,Pb,Ag) are related to subtraction in the Western United State during cretaceous to middle tertiary.
  • Cu, Fe, No, Au and  Ag are closely associated with calkaline magnetism in such zone.
  • The tin  tungsten belts of Bolivia, East India archipelago( an areas  encompasses twelve seas, two gulfs, and one strait in the East Indies)    and South China are located along similar tectonic setting.


Deposits a Divergent Plate Boundaries

  • An example of recent thermal plume(rising air in the lower altitudes of the Earth's atmosphere)generated rift in Red Sea.
  • Valley of the Red Sea has given rise to a number of a hot spring pools.
  • Sulfide deposits and  metallic deposits Fe, In, Cu, Pb,  Au and Ag are formed.


Deposits at along Transform Fault

  • The coast range of California also host late Cenozoic  Mercury deposits.
  • McLaughlin hotspots gold deposit in California coast ranges.
  • Salton sea geothermal system of the Imperial Valley California has a significant energy potential.

शहरों को रोशन करने के लिए अपना 'चांद' बना रहा चीन


कृत्रिम चंद्रमा' लांच करने की तैयारी में जुटा चीन

 


अधिकारियों ने इस प्रोजेक्ट से जुड़ी कुछ ही जानकारियों को साझा किया है। यह विचार एक फ्रांसीसी कलाकार की कल्पना से प्रेरित है, जिसमें उसने धरती को चारों ओर से दर्पणों की माला से घेरने की बात कही थी। चेंगदू एयरोस्पेस साइंस एवं टेक्नोलॉजी माइक्रोइलेक्ट्रॉनिक्स सिस्टम रिसर्च इंस्टीट्यूट कंपनी लिमिटेड के चेयरमैन वू चुनफेड ने इस परियोजना का खुलासा किया। 




चीन का एक शहर कृत्रिम चंद्रमा लांच करने की तैयारी में है। यह कृत्रिम उपग्रह धरती पर करीब 80 किलोमीटर के दायरे को रोशन करेगा। खास बात यह कि यह कृत्रिम चंद्रमा वास्तविक चंद्रमा की अपेक्षा आठ गुना अधिक चमकीला होगा। अभी तक प्रकाशक उपग्रह के रूप में प्रचारित किए जा रहे इस उपग्रह को चेंगदू शहर के दक्षिण पश्चिम इलाके के ऊपर 2020 तक स्थापित किया जाएगा। इंसान का बनाया पहला चांद शिचुआन के शिचांद सेटेलाइट लॉन्च सेंटर से छोड़ा जाएगा. 





फायदे



  • बिजली के खर्च को घटाना चाहता है.
  • यह उपग्रह असली चांद जैसे ही चमकेगा लेकिन इसकी रोशनी उस चांद की तुलना में आठ गुना ज्यादा होगी.
  • 50 वर्ग किलोमीटर के इलाके में करीब 17 करोड़ डॉलर की हर साल बचत होगी.
  • रोशनी का यह जरिया आपदा या संकट से जूझ रहे इलाकों में ब्लैकआउट की स्थिति में राहत के कामों में भी बड़ा मददगार होगा.



नुकसान


  • रोशनी की वजाहा से निंद का पुरा ना होना.
  • चेंगदू शहर की कृत्रिम चंद्रमा से संबंधित परियोजना का विरोध भी शुरू हो गया है।
  • पशु-प्राणियों से लेकर अंतरिक्ष से जुड़ी वेधशालाओं तक पर विपरीत असर पड़ सकता है। 






यह पहली बार नहीं है जब इंसान आकाश में प्रकाश को परावर्तित करने वाले उपकरण लगाने की कोशिश कर रहा है। हालांकि इस दिशा में अभी तक के प्रयास असफल रहे हैं।





Wednesday, October 24, 2018

Plate Tectonic


Image result for Plate tectonics




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.
 Image result for Plate tectonics


  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


Related image

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