An international team of researchers has made a groundbreaking discovery regarding the tectonic evolution of terrestrial planets. Published in the journal Nature Communications, this study systematically classifies six distinct planetary tectonic regimes, introducing a new regime termed the “episodic-squishy lid.” The research enhances our understanding of Earth’s plate tectonics while shedding light on the geological features of Venus.
Understanding Planetary Tectonics
The diverse tectonic regimes of terrestrial planets reflect the large-scale deformation of their surface layers, which directly impacts geological activity, internal evolution, and even the potential for life. One of the most intriguing questions in planetary science is why Earth exhibits active plate tectonics, while Venus, often referred to as its “sister planet,” displays a markedly different geological character.
Mars exemplifies a “stagnant lid” regime, characterized by a mostly immobile surface that preserves ancient impact craters. In contrast, Earth operates under a “mobile lid” regime, marked by a network of mid-ocean ridges, transform faults, and subduction zones. These tectonic boundaries not only generate geological hazards such as earthquakes and volcanism but also contribute to stabilizing Earth’s atmospheric and climatic conditions over millions of years.
Dr. Tianyang Lyu, the first author of the paper from the Department of Earth and Planetary Sciences at The University of Hong Kong, stated, “Through statistical analysis of vast amounts of model data, we were able to identify six tectonic regimes for the first time quantitatively, including the mobile lid and stagnant lid.” The newly introduced episodic-squishy lid presents an alternating activity pattern, suggesting how planets might transition from inactive to active states.
Deciphering Tectonic Patterns
A significant challenge in predicting a planet’s tectonic evolution is the “memory effect,” where a planet’s geological state is influenced not just by current conditions but also by its historical context. Professor Man Hoi Lee noted, “Our models reveal that this ‘memory effect’ is not insurmountable. In scenarios where the lithosphere weakens over time, the transition between tectonic regimes can be surprisingly predictable.”
To illustrate these findings, the research team created a comprehensive diagram that maps all six tectonic regimes under varying physical conditions, outlining probable transition pathways as a planet cools. According to Professor Guochun Zhao, an Academician of the Chinese Academy of Sciences, geological records indicate that early Earth’s tectonic activity aligns with characteristics of the newly identified episodic-squishy lid. As Earth cooled, its lithosphere became increasingly susceptible to fracturing, ultimately leading to the plate tectonics we observe today.
The implications of this research extend beyond Earth. The models suggest that certain surface features on Venus, including the circular “coronae” that span over 1,000 km, resonate with the “plutonic-squishy lid” or “episodic-squishy lid” regimes. In these frameworks, magmatic intrusions weaken the lithospheric lid, resulting in regionally focused tectonic activity driven by mantle plumes rather than widespread plate-boundary deformation.
Co-author Professor Zhong-Hai Li of the University of Chinese Academy of Sciences emphasized the significance of comparing model results with geological observations of Venus, stating, “This provides important theoretical references and observational targets for future Venus missions.”
Ultimately, this research establishes a new framework for categorizing and understanding the diversity of planetary tectonics, offering valuable tools for exploration beyond our solar system. Dr. Maxim D Ballmer from University College London remarked, “Our models intimately link mantle convection with magmatic activity, allowing us to view the geological histories of Earth and Venus within a unified theoretical framework. This foundation is crucial for the search for potentially habitable Earth analogs and super-Earths.”
The findings from this study not only advance our knowledge of planetary sciences but also pave the way for future missions and explorations aimed at understanding our solar system and beyond.
