start-ver=1.4 cd-journal=joma no-vol=965 cd-vols= no-issue=1 article-no= start-page=52 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240404 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Unraveling the Cr Isotopes of Ryugu: An Accurate Aqueous Alteration Age and the Least Thermally Processed Solar System Material en-subtitle= kn-subtitle= en-abstract= kn-abstract=The analysis of samples returned from the C-type asteroid Ryugu has drastically advanced our knowledge of the evolution of early solar system materials. However, no consensus has been obtained on the chronological data, which is important for understanding the evolution of the asteroid Ryugu. Here, the aqueous alteration age of Ryugu particles was determined by the Mn?Cr method using bulk samples, yielding an age of 4.13 + 0.62/?0.55 Myr after the formation of Ca?Al-rich inclusions (CAI). The age corresponds to 4563.17 + 0.60/?0.67 Myr ago. The higher 55Mn/52Cr, 54Cr, and initial 53Cr values of the Ryugu samples relative to any carbonaceous chondrite samples implies that its progenitor body formed from the least thermally processed precursors in the outermost region of the protoplanetary disk. Despite accreting at different distances from the Sun, the hydrous asteroids (Ryugu and the parent bodies of CI, CM, CR, and ungrouped C2 meteorites) underwent aqueous alteration during a period of limited duration (3.8 } 1.8 Myr after CAI). These ages are identical to the crystallization age of the carbonaceous achondirtes NWA 6704/6693 within the error. The 54Cr and initial 53Cr values of Ryugu and NWA 6704/6693 are also identical, while they show distinct '17O values. This suggests that the precursors that formed the progenitor bodies of Ryugu and NWA 6703/6693 were formed in close proximity and experienced a similar degree of thermal processing in the protosolar nebula. However, the progenitor body of Ryugu was formed by a higher ice/dust ratio, than NWA6703/6693, in the outer region of the protoplanetary disk. en-copyright= kn-copyright= en-aut-name=TanakaRyoji en-aut-sei=Tanaka en-aut-mei=Ryoji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=RatnayakeDilan M. en-aut-sei=Ratnayake en-aut-mei=Dilan M. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OtaTsutomu en-aut-sei=Ota en-aut-mei=Tsutomu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MiklusicakNoah en-aut-sei=Miklusicak en-aut-mei=Noah kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KunihiroTak en-aut-sei=Kunihiro en-aut-mei=Tak kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=PotiszilChristian en-aut-sei=Potiszil en-aut-mei=Christian kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=SakaguchiChie en-aut-sei=Sakaguchi en-aut-mei=Chie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=KobayashiKatsura en-aut-sei=Kobayashi en-aut-mei=Katsura kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=YamanakaMasahiro en-aut-sei=Yamanaka en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=AbeMasanao en-aut-sei=Abe en-aut-mei=Masanao kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=MiyazakiAkiko en-aut-sei=Miyazaki en-aut-mei=Akiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=NakatoAiko en-aut-sei=Nakato en-aut-mei=Aiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=NakazawaSatoru en-aut-sei=Nakazawa en-aut-mei=Satoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=NishimuraMasahiro en-aut-sei=Nishimura en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=OkadaTatsuaki en-aut-sei=Okada en-aut-mei=Tatsuaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=SaikiTakanao en-aut-sei=Saiki en-aut-mei=Takanao kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=TanakaSatoshi en-aut-sei=Tanaka en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= en-aut-name=TeruiFuyuto en-aut-sei=Terui en-aut-mei=Fuyuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=19 ORCID= en-aut-name=TsudaYuichi en-aut-sei=Tsuda en-aut-mei=Yuichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=20 ORCID= en-aut-name=UsuiTomohiro en-aut-sei=Usui en-aut-mei=Tomohiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=21 ORCID= en-aut-name=WatanabeSei-ichiro en-aut-sei=Watanabe en-aut-mei=Sei-ichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=22 ORCID= en-aut-name=YadaToru en-aut-sei=Yada en-aut-mei=Toru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=23 ORCID= en-aut-name=YogataKasumi en-aut-sei=Yogata en-aut-mei=Kasumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=24 ORCID= en-aut-name=YoshikawaMakoto en-aut-sei=Yoshikawa en-aut-mei=Makoto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=25 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=26 ORCID= affil-num=1 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=5 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=6 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=7 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=8 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=9 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=10 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=11 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=12 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=13 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=14 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=15 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=16 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=17 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=18 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=19 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=20 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=21 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=22 en-affil=Department of Earth and Planetary Sciences, Nagoya University kn-affil= affil-num=23 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=24 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=25 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=26 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=95 cd-vols= no-issue=4 article-no= start-page=165 end-page=177 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190411 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Hypervelocity collision and water-rock interaction in space preserved in the Chelyabinsk ordinary chondrite en-subtitle= kn-subtitle= en-abstract= kn-abstract=A comprehensive geochemical study of the Chelyabinsk meteorite reveals further details regarding its history of impact-related fragmentation and melting, and later aqueous alteration, during its transit toward Earth. We support an similar to 30 Ma age obtained by Ar-Ar method (Beard et al., 2014) for the impact-related melting, based on Rb-Sr isotope analyses of a melt domain. An irregularly shaped olivine with a distinct 0 isotope composition in a melt domain appears to be a fragment of a silicate-rich impactor. Hydrogen and Li concentrations and isotopic compositions, textures of Fe oxyhydroxides, and the presence of organic materials located in fractures, are together consistent with aqueous alteration, and this alteration could have pre-dated interaction with the Earth's atmosphere. As one model, we suggest that hypervelocity capture of the impact-related debris by a comet nucleus could have led to shock-wave-induced supercritical aqueous fluids dissolving the silicate, metallic, and organic matter, with later ice sublimation yielding a rocky rubble pile sampled by the meteorite. en-copyright= kn-copyright= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KunihiroTak en-aut-sei=Kunihiro en-aut-mei=Tak kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OtaTsutomu en-aut-sei=Ota en-aut-mei=Tsutomu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SakaguchiChie en-aut-sei=Sakaguchi en-aut-mei=Chie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=TanakaRyoji en-aut-sei=Tanaka en-aut-mei=Ryoji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=KobayashiKatsura en-aut-sei=Kobayashi en-aut-mei=Katsura kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=YamanakaMasahiro en-aut-sei=Yamanaka en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=ShimakiYuri en-aut-sei=Shimaki en-aut-mei=Yuri kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=BeboutGray E. en-aut-sei=Bebout en-aut-mei=Gray E. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=MiuraHitoshi en-aut-sei=Miura en-aut-mei=Hitoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=YamamotoTetsuo en-aut-sei=Yamamoto en-aut-mei=Tetsuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=MalkovetsVladimir en-aut-sei=Malkovets en-aut-mei=Vladimir kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=GrokhovskyVictor en-aut-sei=Grokhovsky en-aut-mei=Victor kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=KorolevaOlga en-aut-sei=Koroleva en-aut-mei=Olga kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=LitasovKonstantin en-aut-sei=Litasov en-aut-mei=Konstantin kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= affil-num=1 en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=5 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=6 en-affil=Okayama Univ, Inst Planetary Mat, Pheast Mem Lab Geochem & Cosmochem kn-affil= affil-num=7 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=8 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=9 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=10 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=11 en-affil=Graduate School of Natural Sciences, Nagoya City University kn-affil= affil-num=12 en-affil=Institute of Low Temperature Science, Hokkaido University kn-affil= affil-num=13 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=14 en-affil=Institute of Physics and Technology, Ural Federal University kn-affil= affil-num=15 en-affil=Institute of Mineralogy, Ural Branch of the Russian Academy of Sciences South-Ural State University kn-affil= affil-num=16 en-affil=V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences kn-affil= en-keyword=ordinary chondrite kn-keyword=ordinary chondrite en-keyword=chronology kn-keyword=chronology en-keyword=geochemistry kn-keyword=geochemistry en-keyword=impact melting kn-keyword=impact melting en-keyword=asteroid kn-keyword=asteroid en-keyword=comet kn-keyword=comet END start-ver=1.4 cd-journal=joma no-vol=43 cd-vols= no-issue=1 article-no= start-page=147 end-page=161 dt-received= dt-revised= dt-accepted= dt-pub-year=2018 dt-pub=20181025 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Determination of Abundances of Fifty-Two Elements in Natural Waters by ICP-MS with Freeze-Drying Pre-concentration en-subtitle= kn-subtitle= en-abstract= kn-abstract= To precisely determine the abundances of fifty-two elements found within natural water samples, with mass fractions down to fg g(-1) level, we have developed a method which combines freeze-drying pre-concentration (FDC) and isotope dilution internal standardisation (ID-IS). By sublimation of H2O, the sample solution was reduced to < 1/50 of the original volume. To determine element abundance with accuracy better than 10%, we found that for solutions being analysed by mass spectrometry the HNO3 concentration should be > 0.3 mol l(-1) to avoid hydrolysis. Matrix-affected signal suppression was not significant for the solutions with NaCl concentrations lower than 0.2 and 0.1 cg g(-1) for quadrupole ICP-MS and sector field ICP-MS, respectively. The recovery yields of elements after FDC were 97-105%. The detection limits for the sample solutions prepared by FDC were <= 10 pg g(-1), except for Na, K and Ca. Blanks prepared using FDC were at pg-levels, except for eleven elements (Na, Mg, Al, P, Ca, Mn, Fe, Co, Ni, Cu and Zn). The abundances of fifty-two elements in bottled drinking water were determined from five different geological sources with mass fractions ranging from the fg g(-1) to mu g g(-1) level with high accuracy. en-copyright= kn-copyright= en-aut-name=HoangQue D. en-aut-sei=Hoang en-aut-mei=Que D. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KunihiroTak en-aut-sei=Kunihiro en-aut-mei=Tak kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=SakaguchiChie en-aut-sei=Sakaguchi en-aut-mei=Chie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=YamanakaMasahiro en-aut-sei=Yamanaka en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=5 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=6 en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University kn-affil= en-keyword=pre-concentration kn-keyword=pre-concentration en-keyword=freeze-drying kn-keyword=freeze-drying en-keyword=ID-IS kn-keyword=ID-IS en-keyword=natural water kn-keyword=natural water en-keyword=drinking water kn-keyword=drinking water END start-ver=1.4 cd-journal=joma no-vol=43 cd-vols= no-issue=4 article-no= start-page=611 end-page=633 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190320 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Method to Suppress Isobaric and Polyatomic Interferences for Measurements of Highly Siderophile Elements in Desilicified Geological Samples en-subtitle= kn-subtitle= en-abstract= kn-abstract= Sample decomposition using inverse aqua regia at elevated temperatures and pressures (e.g., Carius tube or high]pressure asher) is the most common method used to extract highly siderophile elements (HSEs: Ru, Rh, Pd, Re, Os, Ir, Pt and Au) from geological samples. Recently, it has been recognised that additional HF desilicification is necessary to better recover HSEs, potentially contained within silicate or oxide minerals in mafic samples, which cannot be dissolved solely by inverse aqua regia. However, the abundance of interfering elements tends to increase in the eluent when conventional ion]exchange purification procedures are applied to desilicified samples. In this study, we developed an improved purification method to determine HSEs in desilicified samples. This method enables the reduction of the ratios of isobaric and polyatomic interferences, relative to the measured intensities of HSE isotope masses, to less than a few hundred parts per million. Furthermore, the total procedural blanks are either comparable to or lower than conventional methods. Thus, this method allows accurate and precise HSE measurements in mafic and ultramafic geological samples, without the need for interference corrections. Moreover, the problem of increased interfering elements, such as Zr for Pd and Cr for Ru, is circumvented for the desilicified samples. en-copyright= kn-copyright= en-aut-name=ZhouXiaoyu en-aut-sei=Zhou en-aut-mei=Xiaoyu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TanakaRyoji en-aut-sei=Tanaka en-aut-mei=Ryoji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YamanakaMasahiro en-aut-sei=Yamanaka en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SakaguchiChie en-aut-sei=Sakaguchi en-aut-mei=Chie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=5 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= en-keyword=highly siderophile elements kn-keyword=highly siderophile elements en-keyword=desilicification kn-keyword=desilicification en-keyword=isotope dilution method kn-keyword=isotope dilution method en-keyword=high resolution ICP-MS kn-keyword=high resolution ICP-MS en-keyword=N-TIMS kn-keyword=N-TIMS END