The international geoscience journal Gondwana Research (a Chinese Academy of Sciences tier 1 Top journal, impact factor 6.2) has published a paper titled “Significant contribution of seamounts to the oceanic rare earth elements budget” by the deep-sea mineral resources science and technology innovation team of the Guangzhou Marine Geological Survey under the China Geological Survey, the team’s latest significant result in deep-sea rare earth research.
Rare earth elements, sometimes called the seasoning of industry in China, are used across 13 fields and more than 40 industries, including electronics and information technology, petrochemicals, metallurgy, machinery and energy. Rare earth resources are scarce worldwide, and heavy rare earths in particular, with limited reserves, wide applications and high value, have become a strategic resource that countries compete to secure. In 2011, Japan first reported that the world’s largest rare earth endowment lies in the deep sea, characterized by enrichment in heavy rare earths and potentially sufficient for centuries of use, opening a global search for deep-sea rare earth deposits. After more than a decade of surveys and research, the broad distribution patterns of deep-sea rare earths are now roughly understood. However, the cycling behavior of rare earths in the deep sea and the enrichment mechanisms it controls have remained unresolved. In particular, the influence of seabed topography and ocean currents on rare earth enrichment was unknown, which has to some extent held back deep-sea prospecting.
The new study focused on the Pigafetta Basin in the western Pacific, the most rare-earth-enriched deep-sea area, with the Central Pacific Basin used for comparison. Based on bottom-current data from long-term moored monitoring, the team systematically analyzed the rare earth element characteristics of bottom seawater and pore water. The results show that seamount topography strengthens bottom-current speeds, and the resuspension of sediment can release large amounts of rare earth elements into seawater. In basin centers where bottom currents are weak, the release of rare earths from sediment into seawater is markedly reduced, so large quantities of rare earths remain in the sediment, forming deep-sea rare-earth-rich deposits.
The research reveals for the first time the relationship between deep-sea rare earth enrichment and seabed topography and ocean currents, and provides an initial picture of the deep-sea rare earth cycling regime and its links to seamounts and currents. Model calculations suggest that the contribution of seamount topography to the global oceanic rare earth cycle has been seriously underestimated: seamounts may release as much as 13 million mol of neodymium into global seawater per year, which makes ocean basins more likely than seamount areas to form rare-earth-rich sediments. The findings are expected to guide future deep-sea rare earth prospecting.
The Guangzhou Marine Geological Survey’s deep-sea mineral resources innovation team is a pioneer of deep-sea rare earth survey and research in China. Addressing the theoretical and technical challenges of surveying this new strategic resource, the team has strengthened basic geological research and recently published a series of papers in journals including Science Advances, Geochimica et Cosmochimica Acta and Gondwana Research, progressively clarifying the enrichment mechanisms and distribution patterns of deep-sea rare earths and providing a theoretical basis for prospecting breakthroughs and national energy and resource security.
The paper’s first author is Dr. Deng Yinan of the Guangzhou Marine Geological Survey, with research professor Guo Qingjun of the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, as corresponding author. The research was jointly funded by the National Natural Science Foundation of China, the National Science Fund for Distinguished Young Scholars, a major talent recruitment project of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), China Geological Survey projects, the national ocean special program’s 13th Five-Year resources and environment projects, and the open fund of the Key Laboratory of Marine Mineral Resources of the Ministry of Natural Resources.
