A group led by researchers at the Energy and Resources Frontier Center, Graduate School of Engineering, the University of Tokyo, said that ultra-high-concentration rare earth mud off the coast of Minamitorishima was generated due to the cooling of the earth that occurred 3450 million years ago. I found out.

 In 2013, the group discovered ultra-high concentration rare earth mud, which is a promising resource for rare earths, in Japan's exclusive economic zone off Minamitorishima.Rare earths are an indispensable element group for advanced technology and high-tech products, and it is expected that if the mechanism of their formation can be elucidated, it will be possible to theoretically predict the distribution in the ocean.

 Previous studies have shown that ultra-high concentration rare earth mud contains a large amount of fossil fish bones (hereinafter referred to as fish bone fragments) that concentrate rare earths from seawater.However, it was unclear when and how a large number of fish bone fragments were deposited.

 This time, the group revealed that ultra-high concentration rare earth mud off Minamitorishima was formed about 3450 million years ago as a result of morphological classification of fossils of fish teeth and dating based on osmium isotope ratio in seawater. ..Furthermore, he found that the amount of fish bone fragments accumulated at that time had increased rapidly, and speculated that the number of fish increased rapidly around Minamitorishima during this period.

 It is thought that this era was the beginning of global cooling, and the cold and heavy seawater in the polar regions sank into the deep sea, strengthening the ocean circulation.When the fortified low-lying current collides with the seamount, upwelling occurs, and a large amount of nutrients accumulated in the deep layer is brought to the surface layer, resulting in a rapid increase in fish around the seamount.Since there is a large seamount off the coast of Minamitorishima, it is thought that it triggered the upwelling and increased the accumulation of fish bone fragments in the surrounding area, resulting in the formation of ultra-high concentration rare earth mud.

 From the northwestern Pacific Ocean including Minamitorishima to the Central Pacific Ocean, there are many large seamounts.From the mechanism clarified in this study, it is highly possible that ultra-high concentration rare earth mud is distributed in the vicinity of these seamounts, and it is considered to be an important exploration target in the future.

Paper information:[Scientific Reports] Fish proliferation and rare-earth deposition by topographically induced upwelling at the late Eocene cooling event

Tokyo University

Established in the 10th year of the Meiji era.A university with the longest history in Japan and at the forefront of Japanese knowledge

The University of Tokyo was established in 1877 (Meiji 10) by integrating the Tokyo Kaisei School and the Tokyo Medical School.Since its establishment, it has developed education and research in a unique way in the world as a leading university in Japan and an academic center for the fusion of East and West cultures.As a result, many human resources have been produced in a wide range of fields, and many research achievements […]

Kobe University

To an outstanding research university that shines with advanced research and fusion research

Kobe University, which is located in a port city open to the world, has 4 faculties and 10 faculties under the 15 university arts series of "humanities / human sciences", "social sciences", "natural sciences", and "life / medical sciences". It is a comprehensive university with a graduate school, one research institute and many centers. Based on the philosophy of "harmony between science and reality," we have strengths in both the humanities and science fields […]

Chiba Institute of Technology

Foster professionals who learn cutting-edge science and technology and contribute to world culture with technology

Chiba Institute of Technology was founded in 1942 as "Koa Institute of Technology" in response to social demands to train advanced science and technology engineers and enrich Asian countries including Japan.In the 17 years since then, it has continued to support Japan's growth through manufacturing, and is now the oldest existing private technical university […].

Waseda University

Reform with the aim of "WASEDA shining in the world" with research, education, and contribution as the three pillars

Waseda University has created an unparalleled environment in which all students can hone their ability to take on unanswered issues based on the three founding principles of "independence of academics, utilization of academics, and creation of model people."Aiming to be a world-class university with unwavering international competitiveness, "WASEDA that shines in the world," "Waseda for research" and "[…] for education.

University Journal Online Editorial Department

This is the online editorial department of the university journal.
Articles are written by editorial staff who have a high level of knowledge and interest in universities and education.