Journal Article

Discovery of Dense Ferromanganese Nodules in the Central Basin of the South China Sea: Insights Into Metallogenesis Processes and Resource Potential

Ma, Jinfeng, Deng, Yinan, Ren, Jiangbo, Zhang, Lixue, Yu, Miao, He, Gaowen, Hong, Shuang, Zhang, Limin, Deng, Xianze, Ren, Yingzhi, Sun, Zhen, Yang, Yong

2025

Overview

Ferromanganese deposits in the South China Sea (SCS) hold significant strategic metal resources, yet their distribution remains poorly understood. To address this gap, we conducted an integrated study across 6,600 km2 in the central basin of the SCS, combining sampling, seafloor video, and multi‐beam backscatter acoustic surveys. A high‐backscatter zone of 1.21 km2 on the Jiaolong seamount was identified as a ferromanganese nodule‐rich area, contrasting with the abyssal basin. The ferromanganese nodules exhibit high vernadite contents and atypical hydrogenesis characteristics, including high Fe/Mn and Fe/Co ratios, and elevated Pb and rare earth element contents. These features suggest that marginal seas are more effective in supplying short‐life cycle elements. Seamounts in the central basin may enhance circulation efficiency, facilitating sediment removal and dissolved oxygen recharge, thereby promoting ferromanganese deposit formation in certain areas. This study contributes to the further exploration of ferromanganese deposits in the SCS. Plain Language Summary Despite geological sampling revealing significant ferromanganese deposits in the South China Sea (SCS), their spatial distribution remains poorly constrained. In this study, multi‐beam backscatter acoustic surveys were used to find high‐reflectivity zones across 6,600 km2 in the central basin of the SCS, and the ferromanganese nodule‐enriched areas and their boundaries were then successively confirmed by geological sampling and seafloor video. A high‐backscatter zone of 1.21 km2 on the Jiaolong seamount was identified as a nodule‐rich area, contrasting with the abyssal basin. We collected 117.8 kg of ferromanganese nodules, which had high vernadite and low todorokite contents, suggesting an oxidized formation environment. Geochemically, these nodules exhibit atypical hydrogenetic characteristics, with high Fe/Mn and Fe/Co ratios, elevated rare earth elements and yttrium (mean 1,969 ppm), and unique elemental signatures (e.g., low Co and high Pb contents). This finding indicates that marginal seas are better at supplying short‐life cycle elements. Seamounts in the central basin may enhance circulation efficiency, facilitating sediment removal, and dissolved oxygen recharge, thereby promoting ferromanganese deposit formation in certain areas. We have modeled the metallogenesis of the ferromanganese nodules and mapped 72,000 km2 of prospective resources, guiding future exploration in the central basin of the SCS. Key Points A high‐backscatter zone spanning 1.21 km2 was proven to be a ferromanganese nodule‐rich area via sampling and seafloor video Ferromanganese deposits in the central basin of the South China Sea are distributed in topographic highlands, not in abyssal basins Atypical hydrogenetic ferromanganese nodule metallogenesis in marginal seas with low Co contents and high Fe/Co ratios is modeled

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Abyssal zone / Backscatter / backscatter intensity / Backscattering / Dissolved oxygen / Echo surveys / Ferromanganese / ferromanganese deposits / Ferromanganese nodules / Heavy metals / Iron / Life cycle / Manganese / Marginal seas / Metallogenesis / Nodules / Ocean floor / Rare earth elements / seafloor video / Seamounts / South China Sea