A theoretical model of continental drift reveals that the longest timescale of sea level change in Earth's history can be explained by the flattening effect of the seafloor
–Toward an understanding of the relationship between Earth's internal dynamics and surface environmental change–

1. Key Points

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We studied the effects of the cycle of supercontinent formation (i.e., the supercontinent cycle) on sea level changes on a time scale of hundreds of millions of years, using a theoretical model that considers different scenarios of the supercontinent cycle.

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When we estimated sea level changes from the breakup of the supercontinent to the formation of the next supercontinent, we found that the "flattening" effect, i.e., the bathymetry above the oceanic plates becoming approximately constant at the old seafloor ages, is essential in reconstructing sea level changes.

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Since the flattening of the seafloor is thought to be a result of mantle convection, the results of this study suggest an indirect link between the large-scale dynamics of the Earth's interior and surface environmental changes via sea level changes.

2. Overview

Dr. Masaki Yoshida of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) has studied the effects of the cycle of continental dispersal and aggregation (i.e., the supercontinent cycle) on sea level changes on the longest time scale in Earth's history, using a theoretical model that considers different scenarios of the supercontinent cycle.

He found that the "flattening" effect of the oceanic plate, which means that the depth of the seafloor (i.e., bathymetry) above the oceanic plates is close to approximately constant at the old seafloor ages (about 60–80 million years since the formation at the ridge), as known from seafloor observations, is important in reconstructing the actual sea level changes of the 200–300 million year cycle as estimated by stratigraphy.

Since some previous studies have suggested that the flattening of the oceanic plates is caused by the uplift of the oceanic plates, i.e., seafloor uplift, as a result of large-scale convective flow in the mantle, the results of this study may provide a new framework for exploring on the relationship between the dynamics of the Earth's interior and environmental changes at the Earth's surface.

This work was supported by JSPS KAKENHI Grant Number JP22K03787. The research paper was published online in Gondwana Research on July 19, 2023.