wilson cycle

Question 1

describe the main stages of the Wilson Cycle (3)

Answer 1

• rifting and formation of a new ocean basin
• ocean basin expansion and mature ocean
• subduction, closure of the ocean, and continental collision

Question 2

explain how the Wilson Cycle can lead to mountain building (orogeny) (4)

Answer 2

• ocean closure due to subduction
• collision of continental plates
• crustal thickening and folding
• formation of fold mountains e.g. Himalayas

Question 3

outline the geological features associated with the opening of an ocean basin (3)

Answer 3

• continental rift valleys
• volcanic activity and intrusion of mafic magma
• eventual development of mid-oceanic ridges

Question 4

describe how subduction contributes to the closing stages of the Wilson Cycle (4)

Answer 4

• oceanic crust being forced beneath another plate
• creation of ocean trenches
• volcanic arcs
• eventual continental collision

Question 5

what evidence supports the existence of ancient Wilson cycles in the geological record (3)

Answer 5

• presence of ancient fold mountain belts e.g. Himalayas
• ophiolite sequences as remnants of oceanic crust
• matching rock assemblages and fossils across now-separated continents

Question 6

compare the early rifting stage and the terminal collision stage of the Wilson Cycle (4)

Answer 6

• early rifting: extensional tectonics and normal faulting
• terminal collision: compressional tectonics and thrust faulting
• early rifting with basaltic volcanism and thinning crust
• collision with crustal shortening and mountain building

Question 7

explain the role of mantle plumes in initiating the Wilson Cycle (3)

Answer 7

• upwelling of hot mantle material (mantle plume)
• doming and fracturing of the continental crust
• triggering continental rifting

Question 8

describe the processes that occur at a convergent plate boundary during ocean closure (4)

Answer 8

• subduction of oceanic crust
• formation of deep-sea trenches
• volcanic activity in island arcs or continental margins
• earthquakes due to friction and slab pull

Question 9

what is meant by the term ‘Wilson Cycle’ and why is it important in understanding plate tectonics (3)

Answer 9

• definition: cyclical opening and closing of ocean basins
• importance: explains the life cycle of oceans and continents
• links tectonic activity, mountain building, and rock formation

Question 10

using a named example, describe a modern setting that represents a stage in the Wilson Cycle (4)

Answer 10

• (identifying a modern example) Red Sea — rifting stage
• (describing tectonic setting) continental plates pulling apart
• (geological features) faulting, basaltic volcanism
• linking to future ocean development if rifting continues