AUTHOR=Li Jie , Jin Yinjia , Wang Hao , Yang Kehong , Zhu Zhimin , Meng Xingwei , Li Xiaohu 

TITLE=In-situ analysis of polymetallic nodules from the clarion-Clipperton zone, Pacific Ocean: implication for controlling on chemical composition variability

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 11 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2024.1489184

DOI=10.3389/fmars.2024.1489184

ISSN=2296-7745

ABSTRACT=The chemical compositions of polymetallic ferromanganese nodules (PMNs) in the Clarion-Clipperton Zone (CCZ) exhibit spatially variability, which increases the difficulty of exploration and associated costs. The primary factors driving this spatial variability is still uncertain, largely due to the limited understanding of the growth history of these PMNs. In this study, we analyzed PMNs from both the eastern and western CCZ using a comprehensive array of in-situ techniques to investigate their internal structure and element distributions.In Nodule BC06 from the eastern CCZ, the Mn/Fe ratio shows a decreasing trend from the inner part (Layer I) to the outer part (Layer II). In contrast, Nodule BC1901 from the western CCZ is composed of three layers. The Mn/Fe ratio increases from Layer I to Layer II and then decreases from Layer II to Layer III. Discrimination diagrams indicate that both of these PMNs formed via hydrogenetic and diagenetic processes, but the layers of Nodule BC06 exhibit stronger diagenetic influences.Moreover, the diagenetic effects within the samples vary from the core to the rim, suggesting different primary controls on the geochemical changes. In the eastern CCZ, the movement of the PMNs away from the equatorial high-productivity zone primarily drives the compositional changes. In the western CCZ, the variability of the deep-water ventilation and the intensity of the Antarctic Bottom Water are the main factors influencing the nodule composition. The results of this study provide insights into the growth history and spatial element distributions of PMNs in the CCZ, which will be beneficial for resource evaluation.