New Study Challenges Prevailing Theory of Earth’s Crust Formation

A recent study conducted by a research team led by Penn State suggests that the formation of Earth’s crust has been a continual slow process of reworking, contrary to what was previously believed. The researchers analyzed over 600,000 rock samples from around the world to chart the Earth’s crustal growth and found evidence of a more gradual growth rather than a rapid slowdown around 3 billion years ago.

The prevailing theory suggested that there was a sudden shift from a stagnant lid planet with no tectonic activity to the formation of tectonic plates. However, the new research challenges this idea and provides insights into the formation of Earth’s crust and possibly other planets.

To determine the crustal growth curve, the researchers used rock samples rather than mineral samples due to their sensitivity and lack of bias. They developed a unique method to analyze how igneous rocks change over time through processes such as weathering and remelting. By comparing their findings with previous studies that used mineral records, the team discovered that the Earth’s crust follows the path of the underlying mantle.

This is not the first time that scientists have suggested a more gradual growth of the Earth’s crust, but it is the first study to use rock records to support this idea. Lead author Jesse Reimink, an assistant professor of geosciences, emphasized that while the research improves our understanding, there is still much more to learn about the Earth’s crust due to the limited data available.

The findings of this study could have implications not only for understanding the Earth but also for studying other planets. For example, the absence of tectonic plates on Venus, known as Earth’s “sister planet,” raises questions about why Earth and Venus evolved differently. The crustal growth rate plays a significant role in answering these questions and shedding light on the evolution of planets on different paths.

Overall, this research challenges the prevailing theory of Earth’s crust formation and provides valuable insights into the gradual growth and reworking of the Earth’s crust over billions of years.

Source: Geochemical Perspectives Letters

Reference: “A whole-lithosphere view of continental growth” by J.R. Reimink, J.H.F.L. Davies, J.-F. Moyen, and D.G. Pearson, 3 August 2023, Geochemical Perspective Letters.

Contributors: Joshua Davies (University of Quebec at Montreal), Jean-François Moyen (University of Lyon, France), and D. Graham Pearson (University of Alberta, Canada).

Funding: This research was partially supported by the Natural Sciences and Engineering Research Council of Canada.