A New Method for Calculating Growth Rates of Ferromanganese Nodules From Marginal Seas: Implications for Terrigenous Input in the South China Sea

Abstract Accurate age determination of marine ferromanganese (Fe‐Mn) nodules is crucial for interpreting their geochemical compositions as paleoceanographic tracers and for understanding critical metal (e.g., Co, Ni) enrichment. Previous empirical dating methods, primarily developed for deep‐ocean nodules, are less effective in marginal seas with high terrigenous input. Here, we propose a novel rare earth elements and yttrium (REY) chronometer tailored for Fe‐Mn nodules from the northeastern South China Sea (SCS). A robust negative correlation is established between the REY content and the growth rate: Growth Rate (mm / Ma) = − 0 . 0186 × REY* + 38 . 301 (R 2 = 0 . 9223) . Based on this model, we find that nodule growth in the SCS accelerated since ∼3.0 Ma, attributed to increased terrigenous input from the uplift of Taiwan. As more nodule data from marginal seas become available, this chronometer can be further refined, offering a reliable time marker for marine archives in these complex environments.