Association patterns of ferromanganese nodule abundance with seafloor topography based on shipborne multibeam bathymetric data in the Pacific Clarion–Clipperton fracture zone and its application

Deep-sea ferromanganese nodules (FNs) are important mineral resources, and their abundance is a key parameter for resource assessment. In this study, the association between FN abundance and seafloor topography near 113 geological sampling stations in the Pacific Clarion–Clipperton Fracture Zone is investigated. Results reveal that FNs are widely distributed on gentle slope terrain with gradients of ∼0.7°–4.6°, where FN abundance is 5–20 kg/m2. In addition, flat terrain slopes with gradients of ∼0°–0.7° can be further divided into two topographic types. Areas at or near local hilltops and ridge tops are associated with FN abundances of 5–20 kg/m2, similar to those observed on gentle slope terrain. In contrast, areas at or near the bottoms of local troughs and depressions exhibit FN abundances of <5 kg/m2 and buried nodules are commonly observed. The available station data are insufficient to establish FN occurrence and abundance on steep slopes with gradients >4.6°. These association patterns provide a preliminary basis for inferring the spatial distribution of FN abundance from full-coverage bathymetric data and can support regional FNs resource assessment.