What Will Happen to Earth's Supercontinents in the Future?

Earth has seen many changes over its 4.6 billion-year history, including the formation and breakup of supercontinents. In the distant past, we have experienced at least three such supercontinents: Rodinia, a second one, and Pangaea. Despite the varied complexity of plate tectonics, a new supercontinent is inevitable, appearing in about another 100 million years or so. This cycle of formation and breakup typically repeats about every 1 billion years, highlighting the natural processes at work on our planet.

Current Phase: The Pulling Apart and Scattering Cycle

Currently, the Earth is in a phase of the pulling apart and scattering of continental plates. This cycle is still underway, and it will be several hundred million years before a new supercontinent comes into being. The recent study by Davies et al. (2018) in Global and Planetary Change explored the possibilities of the next supercontinent, presenting four scenarios based on current rates of plate motion, and allowing for the possibility that some contemporary plate boundaries could become inactive.

Scenario 1: Pangea Ultima

In this first scenario, the Atlantic Ocean closes, and the continental plates reassemble into a new supercontinent called Pangea Ultima. However, past continental configurations show that they have never reunited in the same formation twice. This makes the first scenario less likely to occur as predicted by contemporary models.

Scenario 2: Novopangea

The second scenario suggests the formation of a new supercontinent called Novopangea, contingent upon the closure of the Pacific Ocean and the continued widening of the Atlantic Ocean. This would represent a significant shift in the current geological configuration. The Pacific, containing much of the oldest oceanic crust, is a critical factor in this scenario.

Scenario 3: Aurica

Scenario three envisions a supercontinent called Aurica, which would form by the closure of both the Atlantic and the Pacific during the ongoing supercontinent cycle. A new ocean would need to form, propagating from the Indian Ocean, cutting across Eurasia, up to the Arctic. The zones of weakness for this to occur are still debated by geologists, making it a less predictable scenario.

Scenario 4: Amasia

The final scenario foresees a supercontinent forming around the North Pole called Amasia. In this scenario, both the Atlantic and the Pacific would mostly remain open, and the continents would drift northward, closing the Arctic Ocean. This scenario is driven by anomalies left by the former supercontinent, Pangea, deep in the Earth's mantle.

The Role of Mantle Convection in Supercontinent Formation

Central to the formation and relocation of supercontinents is the process of mantle convection. Mantle convection drives the movement of tectonic plates, which in turn affects the global configuration of continents. However, the process of mantle convection is not fully understood, and there are still significant challenges in predicting these events. Subducted slabs are not recycled without some reorganization of mantle convection, which adds to the uncertainties in these extrapolations.

Conclusion

The process of supercontinent formation and breakup spans millions of years and is governed by complex geological processes. While predictions for the future supercontinents are presented, the exact configuration and timing remain subject to ongoing research and uncertainty. The cycle of continental reconfiguration is a fascinating aspect of Earth's history, and understanding it provides valuable insights into the dynamic nature of our planet.