Relation of the distribution of bottom polymetallic manganese nodules to multibeam backsactter in West Pacific

As the discovery of high abundance and high coverage of manganese nodules in West Pacific has attracted much attention of many countries, how to detect the distribution characteristics of manganese nodules with different coverage and abundance is the focus of current research.In our project, the multibeam backscatter intensity data acquired by EM122 system were used to analysis the distribution characteristics of nodules.The results indicate that the change of backscatter intensity is closely related to nodule coverage, while when the coverage is equal, the change of backscatter intensity reflects the size of the nodule, and when nodules are large (D>6 cm), the backscatter intensity increases obviously.Then the maximum likelihood supervised classification method was used to classify the backscatter intensity data.The results of classification reveal that spatial distribution of sediment, low abundance, medium abundance and high abundance nodules. Significantly, in the deep-sea basin, whereas obvious high-backscatter values are observed on areas of clay deposit, the important difference in backscatter between two geological classes is nearly 20 dB which are pelagic clay sediments and nodules with high abundance around 30 kg/m² in the deep sea basin.