magma plumes and their relationship to plate movement

Question 1

what are hot spots?

Answer 1

areas of high heat within the mantle

Question 2

where are they distributed?

Answer 2

near plate boundaries, some most active occur in middle of plates e.g. Hawaii in middle of pacific ocean

Question 3

what can magma plumes explain?

Answer 3

anomalous volcanism - unexpected/more powerful

Question 4

what is an example of a hotspot?

Answer 4

Hawaii:

• “big island” less than 0.7 million years old
• length of ridge: 2600km
• distance from closest plate boundary: 3200km

Question 5

what is magma plumes relationship with plate movement?

Answer 5

1. convection currents draw heat directly towards a section of lithosphere
2. this section of the crust receives continued and concentrated heat (a thermal plume)
3. the low pressure got mantle finds its way through fissures in the crust
4. volcanoes form as magma escapes - depressing the crust
5. as tectonic plates move over the hotspot, the volcanoes are rafted away and reduce in levels of vulcanicity
6. the plume of heated magma canbe dragged along with the crust, allowing volcanism away from the plume
7. eventually volcanoes become extinct and will erode into seamounts and guyots
8. the process starts again with a new volcano forming over the plume
9. repeat - creates a chain of islands and sea mount e.g. hawaii