JpGU-AGU Joint Meeting 2020

Presentation information

[E] Oral

B (Biogeosciences ) » B-CG Complex & General

[B-CG06] Decoding the history of Earth: From Hadean to the present

convener:Tsuyoshi Komiya(Department of Earth Science & Astronomy Graduate School of Arts and Sciences The University of Tokyo), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Katsuhiko Suzuki(Submarine Resources Research Center, Japan Agency for Marine-Earth Science and Technology), Kentaro Nakamura(Department of Systems Innovation, School of Engineering, University of Tokyo)

[BCG06-01] REY-rich mud in the modern and past oceans

*Yasuhiro Kato1,2, Kazutaka Yasukawa1,2, Junichiro Ohta1,2, Koichiro Fujinaga2,1, Kentaro Nakamura1 (1.Graduate school of Engineering, Univ. of Tokyo, 2.ORCeNG, Chiba Institute of Technology)

Keywords:seafloor mineral resources, rare-earth elements, REY-rich mud, umber, seafloor hydrothermal activity, deep-sea sediment

The potential of deep-sea “REY-rich mud” in the Pacific Ocean as a novel source for rare-earth elements and yttrium (REY) was reported in 2011 [1]. Based on a hemisphere-scale geochemical dataset of deep-sea sediments and a multivariate statistical approach using independent component analysis, we have clarified three key components as the origins of REY-rich mud: hydrogenous Mn-oxides, biogenic Ca-phosphates (fish remains), and hydrothermal Fe-oxyhydroxides [2]. Along the spreading axis, scavenging of REY dissolved in seawater by highly absorptive hydrothermal Fe-oxyhydroxide particles causes REY-rich mud with high Fe concentrations [1, 2].

Owing to plate tectonics, deep-sea sediments deposited in the past now constitute accretionary complexes along subduction margins. Therefore, REY-rich mud in the past ocean is expected to be found in the accretionary complexes. One of such a counterpart of REY-rich mud is a metalliferous sedimentary rock called “umber.” In the presentation, we will provide an overview of REY-rich mud from a modern seafloor deposit to an ancient analogue.

[1] Kato, Y. et al. (2011) Nat. Geosci. 4, 535–539.

[2] Yasukawa, K. et al. (2016) Sci. Rep. 6, 29603.