Geotectonics
- 1. “LIFE CYCLE OF OCEANIC CRUST, SPREADING RIDGES & OPHIOLITES”
- 2. PRESENTED BY : SARDAR OBAID-UR-REHMAN ENROLLMENT # : 46 SEMESTER : 7TH (MORNING) “GEO-TECTONICS”
- 3. WHAT IS OCEANIC CRUST ? Oeanic crust, the outermost layer of Earth’s lithosphere that is found under the oceans and formed at spreading centers on oceanic ridges, which occur at divergent plate boundaries. 1. Oceanic crust is about 6 km (4 miles) thick. 2. The topmost layer, about 500 meters (1,650 feet) thick. 3. It is thinner, denser, younger. 4. Oceanic crust is destroyed in subduction zones.
- 4. EXPLORING THE LAYERS IN OCEANIC CRUST
- 5. “LIFE CYCLE OF OCEANIC CRUST + SPREADING RIDGES”
- 6. WILSON CYCLE
- 7. WHAT IS SPREADING RIDGES ? A spreading ridge is the fracture zone along the ocean bottom where molten mantle material comes to the surface, thus creating new crust. This fracture can be seen beneath the ocean as a line of ridge that form as molten rock reaches the ocean bottom and solidifies.
- 8. HOW OCEANIC CRUST IS FORMED AND DESTROYED? Oceanic crust is formed at mid- oceanic ridges, whereas oceanic crust is destroyed at sub duction zone.
- 9. INTERESTING INFORMATION The speed of crust formation varies from ridge to ridge: Some fast-spreading ridges produce up to 6 inches (15 centimeters) of new crust per year, while slower-spreading ridges creep along at just 2 inches (5 cm) per year.
- 10. FORMATION & DESTRUCTION OF OCEANIC CRUST
- 11. “OPHIOLITES”
- 12. HISTORY OF OPHIOLITE “Ophio” is a Greek word which was used for “SNAKE”, Lite means “STONE” and it is also derived from Greek word “Lithos”. The name is given because ophiolites have similarity in colour and texture with snakes, some greenish colour.
- 13. DEFINITION An ophiolite is a section of the earth’s oceanic crust and the under lying upper mantle that has been uplifted or emplaced to be exposed within continental crustal rocks.
- 15. SIMILARITY B/W OCEANIC CRUST & OPHIOLITES
- 17. EURASIAN BLOCK OPHIOLITES Dargai. Mingora – Bajaware. Chilas.
- 18. EXISTENCE OF OPHIOLITE WORLDWIDE