The Significance of Nanomineral Particles during the Growth Process of Polymetallic Nodules in the Western Pacific Ocean

Abstract

As a huge reservoir of economic metallic elements, oceanic polymetallic nodules have important strategic significance and are one of the main research objects in marine geology, especially their formation process and genetic mechanism. In this study, polymetallic nodules from the cobalt-rich crust exploration contract area in the Western Pacific Ocean were taken as the research object. Optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS) were used for observation and testing. The results indicate that many nanomineral particles, mainly composed of Fe and Mn, developed in polymetallic nodules from the western Pacific Ocean. The solid–liquid interface process of nanomineral particles plays an important role in the growth and evolution of nodules. We propose that the growth process of polymetallic nodules in the western Pacific Ocean can be divided into three stages. First, terrigenous detritus nucleates, and nanomineral particles composed of Fe, Mn, and other elements form, aggregate and attach to the core to form the initial shell. Second, a dense layer of the shell forms under stable conditions. In the third stage, the redox conditions of the nodules change, and the polymetallic nodules experience a variety of interface process modifications.

Nano-Mineralogy and Mineralization of the Polymetallic Nodules from the Interbasin of Seamounts, the Western Pacific Ocean

“…The flat top has a depth of 1400-1600 m, and the base has a water depth of around 5000-6000 m. The slope of the mountain top is generally less than 2°. The sediment on the seabed in the study area primarily consists of deep-sea clay, and the bottom seawater is predominantly influenced by the Antarctic bottom water (AABW) (He et al, 2001; [24,28]. The samples were provided by the 32nd (in 2014) and 41st (in 2016) expeditions of the China Oceanic Survey.…”

“…Nano-mineralogy is a promising field for investigating the mechanism of metallic element enrichment in Fe-Mn nodules. The presence of nanoscale minerals has been confirmed in the mineral composition of the Fe-Mn nodules (Shi et al, 1995;Bai et al, 2002 [22][23][24]. Nanoscale minerals exhibit unique nano-properties that are not present in crystalline and amorphous minerals.…”