Plate Tectonic Theory PDF

Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph...

Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si g ha t PLATE TECTONIC THEORY  The Earth’s crust and upper mantle (i.e lithosphere)are broken into sections called plates. t ha TECTONIC PLATES/ LITHOSPHERIC PLATES g Pa y si ph These are massive, irregularly-shaped slab of solid rock, e, ra eg og generally composed of both continental and oceanic ll Ge lithosphere Co f u o hr nt Ne e tm The crust and part of the upper mantle = lithosphere al ar 5-100 km thick in oceanic areas rl ep ha D  200 km thickness in continental areas Less dense than the material below it, so it “floats” wa Ja  What is the Asthenoshere? t ha The plastic/ductile layer below the g Pa y si ph e, ra lithosphere = asthenosphere eg og ll Ge The plates of the lithosphere float on Co f u o hr nt the asthenosphere Ne e tm al ar rl ep ha D wa Ja Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ASTHENOSPHERE ph Pa y si g ha t MESOSPHERE LITHOSPHERE Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t  Principles of plate tectonics The Earth is composed of a mosaic of thin rigid plates (pieces of lithosphere) that move t ha horizontally with respect to one another g Pa y si ph e, ra Plates interact with each other along their eg og ll Ge plate boundaries Co f u o Plate boundaries associated with tectonic hr nt Ne e tm activity (mountain building, earthquakes, al ar active volcanoes) rl ep ha D wa Ja  2 Types of Plates t Oceanic plates - plates below the oceans ha g Pa y si ph Continental plates - plates below the e, ra eg og continents ll Ge Co f u o hr nt Ne e tm al ar rl ep ha D wa Ja Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t  Major tectonic plates Antarctica and the surrounding oceanic plate t ha North American plate g Pa y si ph e, ra South American plate eg og ll Ge Pacific plate Co f u o India-Australia-New Zealand plate hr nt Ne e tm Africa with the eastern Atlantic floor plate al ar rl ep Eurasia and the adjacent oceanic plate ha D wa Ja  Minor tectonic plates Cocos plate: Between Central America and Pacific plate Nazca plate: Between South America and Pacific plate Arabian plate: Mostly the Saudi Arabian landmass t ha Philippine plate: Between the Asiatic and Pacific plate g Pa y si ph Caroline plate: Between the Philippine and Indian plate e, ra eg og (North of New Guinea) ll Ge Fuji plate: North-east of Australia. Co f Turkish plate, u o hr nt Ne e Aegean plate (Mediterranean region), tm al ar Caribbean plate, rl ep Juan de Fuca plate (between Pacific and North American ha D plates) wa Iranian plate. Ja Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t  The 3 types of plate boundaries 1. Divergent t ha g Pa y si ph e, ra eg og ll Ge 2. Convergent Co f u o hr nt Ne e tm al ar rl ep ha D 3. Transform fault wa Ja Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t  Features of Divergent Boundaries Mid- ocean t ridges ha g Pa y si ph rift valleys e, ra eg og fissure ll Ge Co f volcanoes u o hr nt Ne e tm al ar rl ep ha D wa Ja  Divergent plate boundaries The Mid- Atlantic t ha Ridge is a g Pa y si ph divergent e, ra eg og plate ll Ge boundary Co f where u o hr nt Ne e sea floor tm al ar spreading rl ep ha D occurs wa Ja  basin by sea floor rifting and spreading Formation of an ocean Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t  Causes of Plate Tectonics t Convection Currents ha g Pa y si ph e, ra eg og Hot magma in the Earth moves toward the ll Ge Co f surface, cools, then sinks again. u o hr nt Creates convection currents beneath the Ne e tm al ar plates that cause the plates to move. rl ep ha D wa Ja Ja wa ha D rl ep al ar tm Ne e hr nt u o Co f ll Ge eg og e, ra ph Pa y si gha t  Comparison: Continental Drift – See Floor Spreading – Plate Tectonics Continental Drift See Floor Spreading Plate Tectonics Explained Alfred Wegener in Arthur Holmes explains In 1967, McKenzie and t ha by 1920s Convectional Current Theory Parker suggested the theory g Pa y in 1930s. of plate tectonics. The si ph Based on convectional theory was later outlined by e, ra eg og current theory. Harry Hess Morgan in 1968 ll Ge explains Sea Floor Spreading Co f in 1940s u o hr nt Theory Explains Movement Explains Movement of Explains Movement of Ne e tm of Continents only Oceanic Plates only Lithospheric plates that al ar include both continents rl ep ha D and oceans. wa Buoyancy, gravity, Convection currents in Convection currents in Forces for Ja pole fleeing force, tidal the mantle drag crustal the mantle drag crustal movement currents, tides, plates plates  Contd... Apparent affinity of Ocean bottom Ocean bottom relief, physical features, botanical relief, Paleomagnetic rocks, evidence, fossil evidence, Paleomagnetic distribution of Evidences Tillite deposits, placer rocks, earthquakes and t ha deposits, rocks of same age distribution of volcanoes, gravitational g Pa y si ph across different continents earthquakes and anomalies at trenches, e, ra etc. volcanoes etc. etc. eg og ll Ge Too general with silly and Doesn’t explain Co f Drawbacks sometimes illogical u o the movement of ——————— hr nt evidences. continental plates Ne e tm al ar Acceptance Totally discarded Not complete Most widely accepted rl ep ha D Helped in the evolution of Helped in the Helped understand convectional current theory wa Usefulness evolution of plate various geographical and see floor spreading Ja tectonics theory features. theory