According to the University of Tokyo, the research group analyzed deep-sea sediments collected from a wide range of 101 sites in the Pacific Ocean and the Indian Ocean, and the components closely related to the formation of deep-sea sediments containing a large amount of rare earth are of hydrothermal origin. , Seawater origin, discovered to be a biological source of calcium phosphate.

　Furthermore, when these components were investigated, the source of rare earths collected at high concentrations was seawater, and the substances that hold the rare earths were in contact with the seawater for a long period of time, resulting in the uptake of large amounts of rare earths and the formation of deep-sea sediments. It became clear that it was composed.

　One of the conditions required to produce relatively high-grade deep-sea sediments with a total rare earth concentration of over 1,000 PPM is an extremely slow sedimentation environment in which only about 1 milligrams of material is deposited per million years. I also understood.

　In addition, the research group has succeeded in visualizing the spatiotemporal variation of rare earth concentrated components over the past 6,500 million years for the first time in the world by combining statistical analysis, age values ​​of samples by biological fossils, and plate tectonics.As a result, it was confirmed that the production of marine mineral resources is closely related to continental drift and global environmental changes in the long time of tens of millions of years.

* 1 Rare earth A general term for 57 lanthanoid elements from atomic number 71 lanthanum to 15 lutetium.Since it has unique optical and magnetic characteristics, it is indispensable for cutting-edge energy saving and eco-technology.