Researchers at the University of Adelaide have found that ancient tectonic movements deep beneath Earth’s surface played a major role in forming rare-earth mineral deposits.
The discovery helps scientists better understand where many rare minerals are found today. Experts say the findings can support faster and more targeted mineral exploration as global demand for clean energy materials continues to grow.
The study, published in Science Advances, links ancient subduction zones to the formation of rare-earth-element deposits worldwide.
Subduction occurs when one tectonic plate sinks beneath another, deep within Earth. This process changes the surrounding mantle and creates the right conditions for valuable mineral-rich deposits to form over time.
Rare earth elements(REEs), are used in electric vehicles, wind turbines, smartphones, defence equipment, and many advanced electronics. These minerals are difficult to replace in modern technology because of their magnetic and conductive properties. Finding large and economically useful deposits remains a major challenge for many countries.
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The research was led by Professor Carl Spandler from the university’s School of Physics, Chemistry and Earth Sciences. His team studied Earth’s geological history over the past 2 billion years using advanced tectonic and plate-movement models. The goal was to identify regions deep below the surface where ancient subduction activity changed the mantle over time.
Researchers found that many carbonatites and rare-earth deposits occur above mantle regions altered by ancient subduction events. Carbonatites are rare magmatic rocks that often contain large amounts of rare-earth elements. These rocks form from deep melting processes inside Earth’s mantle.
The study showed that around 67 percent of known carbonatites and 72 percent of rare-earth deposits formed over the last 1.8 billion years are linked to these ancient mantle zones. For deposits older than that, the connection rises to 92 percent. The findings suggest that ancient tectonic processes played a much larger role than previously believed.
Scientists also found that these enriched mantle regions cover nearly 35 percent of Earth’s continental crust today. Areas where several subduction events overlapped over time were associated with particularly high concentrations of rare-earth deposits. This provides mining companies and governments with a clearer map for future exploration.
Professor Spandler said the research changes how scientists understand the origin of these essential minerals. He explained that the key ingredients for rare-earth deposits were deposited deep within Earth millions or even billions of years ago. According to the study, these materials remained stored in the mantle until later geological events triggered melting and magma formation.
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The study challenges earlier theories that mainly linked rare-earth deposits to mantle plumes rising from deep within Earth. Instead, the researchers described a two-stage geological process. First, subduction enriches the mantle with important elements, and later heating events produce mineral-rich magma.
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Co-author Andrew Merdith said the findings can make mineral exploration more efficient and targeted. Instead of searching across large regions, companies can focus on ancient tectonic zones identified by the research. This approach can reduce exploration costs and improve the chances of finding new deposits.
The findings arrive at a time when global demand for rare earth minerals is increasing quickly. Countries are investing heavily in electric vehicles, renewable energy systems, battery storage, and advanced defence technologies. Many governments are also trying to reduce dependence on limited overseas mineral suppliers.
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The study also provides insights into Earth’s long-term geological evolution. Researchers said the same deep mantle processes are linked to the storage of water and carbon beneath Earth’s surface. This can improve scientific understanding of volcanic activity, climate history, and continental development over billions of years.
The research was carried out with support from the ARC Centre in Critical Resources for the Future. Scientists believe the findings will shape future exploration strategies as nations search for stable supplies of essential minerals. The work also highlights how ancient geological events continue to influence modern technology and global energy systems today.
