To Reveal the Occurrence States and Enrichment Mechanisms of Metals in Modules From Clarion-Clipperton Zone in Eastern Pacific by High Resolution Spectroscopy

The Clarion-Clipperton Zone (CCZ) in the equatorial eastern Pacific is the most economically potential nodule metallogenic belt globally. There are huge amounts of Mn, Co, Ni, Cu, Zn and Li metal resources in the CCZ. Previous studies focus on chemical and mineralogical analysis, lacking high-resolution spectroscopy analysis of micro-layers and metal distributions, thus resulting in a weak understanding of the enrichment mechanism of metals. In this study, high resolution scanning electron microscopy (SEM) X-ray diffraction (XRD) micro-area X-ray fluorescence surface scan (u-XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to analyze the micro-lamina of nodules. The result shows that the nodule consists of hydrogenic and diagenetic alternating rhythms. The hydrogenic layer comprises Fevernadite, yields low Mn/Fe ratio, Li, Ni, Cu, Zn contents, and high Co, Fe, Ti contents. The hydrogenation layer adsorbs high Co, Ti and V contents due to the coulomb adsorption of FeOOH and surface oxidation of the high valence phyllomanganate octahedral layer. The diagenetic layer is birnessite, showing a high Mn/Fe ratio, Li, Ni, Cu and Zn contents. Its absorptive capacity of metals increases with Mn/Fe ratio and reaches its peak when Mn/Fe>8. The author proposes that the relative Mn and Fe fluxes during nodule accretion control the nodule's mineral type and chemical composition, and the metal flux may also affect the metal composition of the nodule.