3 PLATE TECTONIC SUPERCYCLE

Question 1

Stage 1

Answer 1

Land exists as a stable craton and the heat and pressure from a mantle plume force splits in the continent

Question 2

Stage 2

Answer 2

Land is ripped apart and rifting occurs in the space between

Question 3

Stage 3

Answer 3

More rifting occurs and seafloor spreading creates a mid-ocean ridge as continents move apart and spread around the globe

Question 4

Stage 4

Answer 4

The continents approach and converging plates meet, causing subduction and creating volcanoes

Question 5

Stage 5

Answer 5

Subduction slows as the continents converge and a new supercontinent is formed

Question 6

Impact on evolution (Several land masses)

Answer 6

• Plate tectonics forces arrangement of continents and the ocean basins, altering environments and perhaps driving evolution.
• Increased speciation rates may result from the release of nutrients from newly weathered land masses in the uplifted mountain ranges.
• Research suggests a correlation between the new levels of speciation and major mountain-building events.
• Rate of evolution speeds up as there is a greater variety of habitats (land and sea) → more opportunities for the evolution of new species which leads to GREATER DIVERSITY

Question 7

Impact on evolution (single supercontinent)

Answer 7

Rate of evolution slows down → LESS DIVERSITY. This is because more land masses are at the same latitude and have similar climates.

Question 8

Impact on climate (Several land masses)

Answer 8

• Increased volcanic activity due to rifting and seafloor spreading can release more CO2 into the atmosphere, contributing to greenhouse warming.
• As the continents break up, sediments begin to decrease, CO2 build back up in the atmosphere
• When average temperatures are increased, there is more evaporation and rainfall, which increases sea levels to cover continental margins and create shallow seas, making the climate warm and wet

Question 9

Impact on climate (a single supercontinent)

Answer 9

• Less volcanic activity and subduction decreases the level of CO2, the reduced greenhouse effect lowers average temperatures
• Weathering of a continental mass and its fold mountains is maximized
• Sediments can absorb CO2 from the atmosphere, potentially leading to an ice age.
• When average temperatures are lowered, there is less evaporation and rainfall, which causes a permanent ice cap to form, making the climate cold and dry

Question 10

How long is the process

Answer 10

400 to 600 million years,