New Findings from HKU: Early Continental Formation Driven by Mantle Plumes

Research conducted by geologists from The University of Hong Kong (HKU) has revealed groundbreaking insights into the formation of Earth’s early continental crust during the Archean eon, more than 2.5 billion years ago. The study, recently published in *Science Advances*, posits that mantle plumes, rather than modern plate tectonic processes, were primarily responsible for shaping the early continents. This perspective challenges long-held views regarding the origins of continental crust, which have predominantly emphasized the role of subduction and tectonic plate interactions.

Dr. Dingyi Zhao, a postdoctoral fellow at HKU’s Department of Earth and Planetary Sciences and the study’s lead author, noted, “Our results provide strong evidence that Archean continental crust did not have to be formed through subduction. Instead, a two-stage process involving mantle plume upwelling and gravitational sagduction of greenstones better explains the geochemical and geological features observed in the Eastern Block.”

The researchers, including Professor Guochun Zhao and Xiangsong Wang, investigated ancient granitoid rocks known as TTGs (tonalite-trondhjemite-granodiorite) found in northern China, which date back approximately 2.5 billion years. By utilizing advanced isotopic analysis techniques on zircon minerals within these rocks, the team was able to determine specific conditions under which these rocks formed. Their findings indicated that the TTGs emerged in high-temperature, low-water environments, which contrasts with conditions typical of subduction zones.

The study proposes a two-stage model for the formation of TTGs: first, a mantle plume generated significant basalt deposits on the seafloor around 2.7 billion years ago. Subsequently, another plume initiated partial melting of these basalts around 2.5 billion years ago, leading to the formation of lighter TTG rocks that would eventually constitute the continental crust.

The implications of this research extend beyond geological curiosity; they reshape our understanding of early Earth's dynamics and the processes that fostered life on the planet. Professor Fang-Zhen Teng from the University of Washington remarked, “This work is a great contribution to the study of early Earth geodynamics. Our uses of zircon water and oxygen isotopes have provided a powerful new window into the formation and evolution of early continental crust.”

The research emphasizes the importance of mantle plumes in continental formation, suggesting that these geological features played a pivotal role in Earth's early evolutionary history. This study contributes to the growing body of evidence supporting the mantle plume theory and highlights the necessity for further investigations into the geochemical signatures of ancient rocks to uncover the mysteries of Earth’s past.

In conclusion, the findings from HKU not only provide new insights into the formation of Earth's early continental crust but also underscore the significance of mantle dynamics in shaping our planet’s geological history. As research continues, it may lead to a more refined understanding of the processes that govern Earth's evolution and the conditions that made it hospitable for life.

For further details, the complete study can be accessed in *Science Advances* (2025), DOI: 10.1126/sciadv.adr9513.