GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
Special Issue: Front Edge of Submarine Mineral Resources Research in Japan (Part 2)
Geochemistry of REY-rich mud in the Japanese Exclusive Economic Zone around Minamitorishima Island
Koichiro FujinagaKazutaka YasukawaKentaro NakamuraShiki MachidaYutaro TakayaJunichiro OhtaShuhei ArakiHanjie LiuRyo UsamiRyota MakiSatoru HaraguchiYoshiro NishioYoichi UsuiTatsuo NozakiToshitsugu YamazakiYuji IchiyamaAkira IjiriFumio InagakiHideaki MachiyamaKoichi IijimaKatsuhiko SuzukiYasuhiro KatoKR13-02, MR13-E02 Leg 2 and KR14-02 Cruise Members
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2016 Volume 50 Issue 6 Pages 575-590

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Abstract

We report detailed lithological and chemical characteristics of deep-sea sediments, including rare-earth elements and yttrium-rich mud (REY-rich mud), in the Japanese Exclusive Economic Zone (EEZ) around Minamitorishima Island. Three research cruises obtained fourteen sediment cores collected by piston coring. Based on the visual descriptions and geochemical analysis of the sediment cores, we confirm the presence of REY-rich mud containing more than 400 ppm total REY (∑REY) in the southern and northwestern areas of the Minamitorishima EEZ. The REY-rich mud layers are characterized by abundant grains of phillipsite, biogenic calcium phosphate, and manganese oxides, and are widely distributed in relatively shallow depths beneath the seafloor. In contrast, relatively thick, non-REY-rich mud lies near the seafloor in the northern areas of the EEZ. In the three cores from the southern part of the EEZ, we also confirm the presence of highly/extremely REY-rich mud layers. Further accumulation of geochemical data from the sediments will be required to constrain the extent of the highly/extremely REY-rich mud layers.

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© 2016 by The Geochemical Society of Japan
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