Constructive Plate Margins - Revision Using the following key words, draw a constructive plate margin on your white board and label correctly Sea floor spreading Magnetic strips Divergent Basalt intrusion Upper Mantle partial melting Ocean ridge High heat flow Transform faults Abyssal plain

Constructive Plate Margins - Revision Using the following key words, draw a rift valley and label the parts Normal faults Basalt Convection currents Basalt intrusion Upper Mantle partial melting High heat flow

Plate Margins Three main types of plate margin: Constructive Destructive Conservative Each type of plate margin has different rocks and types of hazard – why ?

Destructive Plate Margins May also be called convergent plate margins. Why? There are three types of destructive plate margins depending on what type of plates are involved: Oceanic v Oceanic Oceanic v Continental Continental v Continental Each will produce different hazards and rocks

Pre-Continent/Continent Collision Features Partial melting of oceanic plate basalt and continental plate granite = andesitic/granitic magma Where might we find andesitic rocks? Subduction zone: describes the whole area where subduction is taking place Ocean Trench: is the deep valley formed in the ocean floor as the subducted plate bends Benioff zone: zone of earthquakes set off by the solid lithospheric plate forcing it’s way through the mantle

Oceanic v Oceanic Collision Island Arc: An arc of islands running parallel to the trench/subduction zone created by volcanic activity fed by magma from the melting subducted plate Label: Trench Island Arc System Benioff Zone Cold, Hot Regions Why would one oceanic plate subduct beneath another ? What type of rock would we find here ?

Continent/Continent Collision Eurasian Plate About 40 million years ago India collided with Asia and a huge mountain chain formed. Both plates were made of continental crust When partial melting occurs beneath two continents colliding, what rock type would be produced ? Indo-Australian Plate Why did they collide ? What destructive zone features are missing ? Granite Subduction zone Trench Volcanoes

Homework For Monday – see slip