Magma and Plate Tectonics Concepts

Dr. Christopher White explains the formation of igneous rocks, focusing on magma generation at divergent plate boundaries. He describes the process of decompression melting and the structure of oceanic lithosphere, including mantle peridotites, gabbros, sheeted dike complexes, and pillow basalts. The video also covers continental divergent boundaries, where mafic magma interacts with continental crust, leading to the formation of felsic and intermediate magmas.

What percentage of all magma is generated at divergent plate boundaries?

• 30%

• 60%

• 90%

• 100%

What is the primary role of the asthenosphere in oceanic divergent plate boundaries?

• To cool down the crust

• To rise and fill the space created by thinning crust

• To create earthquakes

• To form mountains

What happens to mantle peridotite when it is brought to a lower pressure region?

• It cools down

• It solidifies

• It remains unchanged

• It melts through decompression

Which layer in the oceanic lithosphere is formed by vertical sheets of basalt?

• Mantle rocks

• Sheeted dike complex

• Pillowed basalts

• Gabbros

What is the result of magma reaching the sea floor in oceanic divergent plate boundaries?

• Cooling of the ocean

• Formation of pillowed basalts

• Creation of earthquakes

• Formation of mountains

What is the typical temperature of mafic magma?

• 500°C

• 800°C

• 1200°C

• 1500°C

What happens when mafic magma interacts with continental crust?

• It forms mountains

• It cools down and solidifies

• It melts the continental crust

• It causes earthquakes

What type of magma is formed by the melting of continental crust?

• Felsic magma

• Intermediate magma

• Ultramafic magma

• Mafic magma

In continental divergent plate boundaries, what additional process contributes to magma production?

• Cooling of the crust

• Crustal heating

• Mountain formation

• Earthquake activity

What is the result of mafic magma finding a large fault in continental divergent plate boundaries?

• It causes an earthquake

• It erupts into the rift valley

• It solidifies underground

• It forms a lake