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How does the supercontinent cycle describe the repeated assembly and breakup of landmasses?
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paleogeography
Watch a time-lapse of Earth changing through geologic time, from the Cambrian Era to the projected period of Pangea Proxima.
The supercontinent cycle describes a recurring pattern in paleogeography where Earth’s landmasses periodically consolidate into a single supercontinent, disperse, and eventually reassemble in new configurations over intervals of approximately 300 million to 500 million years.12
Mechanisms of Breakup and Assembly
- Breakup: A leading theory suggests that supercontinents act as thermal insulators, trapping heat in the mantle beneath them. This buildup of heat generates vast volumes of magma, which causes the landmass to arch, crack, and eventually rift apart through seafloor spreading.1
- Assembly: As oceanic lithosphere ages, it becomes gravitationally unstable and subducts. This process creates subduction zones that pull continental fragments together. Because continental crust is too buoyant to subduct, these fragments collide and weld together to form a new supercontinent.12
Models of the Cycle
Geologists use three primary models to explain how these fragments reconsolidate:
* Introversion: Fragments are drawn back together by subduction zones that develop within the newly formed interior ocean.2
* Extroversion: Fragments drift apart and collide on the opposite side of the globe as the original exterior ocean closes.2
* Orthoversion: Fragments collide within a band of subduction located roughly 90° away from the center of the previous supercontinent.2