Japan Geoscience Union Meeting 2021

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[J] Oral

H (Human Geosciences ) » H-RE Resource and Engineering Geology

[H-RE12] Resource Geology

Thu. Jun 3, 2021 1:45 PM - 3:15 PM Ch.15 (Zoom Room 15)

convener:Tsubasa Otake(Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University), Kenzo Sanematsu(Mineral Resource Research Group, Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology), Ryohei Takahashi(Graduate School of International Resource Sciences, Akita University), Tatsuo Nozaki(Submarine Resources Research Center, Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology), Chairperson:Tatsuo Nozaki(Submarine Resources Research Center, Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology), Ryohei Takahashi(Graduate School of International Resource Sciences, Akita University)

2:00 PM - 2:15 PM

[HRE12-02] A rapid analytical method of Re-Os isotope on sulfides by MC-ICP-MS and sparging method: Its application to the Kamaishi deposit in NE Japan

*Mizuki Ogasawara1, Junichiro Ohta1,2, Mizuki Ishida1, Moei Yano2,1, Ryota Maki1, Tatsuo Nozaki3,1,4,2, Yutaro Takaya5,3,2, Koichiro Fujinaga2,1, Kazutaka Yasukawa1,2, Yasuhiro Kato1,2 (1.School of Engineering, The University of Tokyo, 2.ORCeNG, Chiba Institute of Technology, 3.JAMSTEC, 4.Kobe University, 5.Waseda University)


Keywords:Re-Os isotopes, MC-ICP-MS, sparging method, sulfide deposits

The Re-Os isotope system is a powerful tool in geological/geochemical studies, especially in radiometric dating of sulfide minerals, black shale and meteorite. Since both Re and Os are siderophile and chalcophile elements enriched in various sulfide minerals, the Re-Os isotope geochronology has been applied to the direct age determination of sulfide mineralization. However, the conventional analytical method of the Re-Os isotope dating using a N-TIMS is time-consuming and requires some reagents harmful to the human body. Also, the simpler, more rapid and safer sparging method for Os isotope analysis using a MC-ICP-MS [1,2] had not been applied to sulfide minerals.

Here, we present an improved analytical method for the Re-Os isotope and its first application to the Kamaishi skarn sulfide deposits in NE Japan. In our method, 0.4 g of powdered sulfide was digested by 1 mL of HClO4 and 4 mL of inverse aqua regia in the Carius tube, which was analyzed using a MC-ICP-MS. The isotopic compositions of 187Os/188Os and 187Re/188Os obtained in the present study showed good agreements with those obtained by the conventional method digesting 0.5 g of the same powdered sample using 10 mL of inverse aqua regia and measuring with a N-TIMS. The less volume of sample solution is favorable for Re-Os isotope analysis by the sparging method using a MC-ICP-MS to accomplish low blank level, which enables us a simpler and more efficient analytical procedure for Re-Os dating on sulfide deposits.



1: Nozaki, T. et al. (2012) Geostand. Geoanal. Res. 36, 131-148.

2: Kimura, J.-I. et al. (2014) J. Anal. Atom. Spectr. 29, 1483-1490.