研究者詳細 - 牧嶋　昭夫

論文 - 牧嶋　昭夫

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Trace element and isotopic geochemistry of Cretaceous magmatism in NE Asia: Spatial zonation, temporal evolution, and tectonic controls 査読

Petr L. Tikhomirov, Elena A. Kalinina, Takuya Moriguti, Akio Makishima, Katsura Kobayashi, Eizo Nakamura

Lithos 264 453 - 471 2016年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Results of a comprehensive geochemical study (major and trace elements, and isotopes of Sr, Nd, Pb, Hf) of Cretaceous volcanic rocks from the Chukotka area in northeastern Russia are presented. Synthesis of available geological and geochronological data suggests diachronous onset of activity of the Okhotsk-Chukotka volcanic belt (OCVB), the largest magmatic province in the region. The OCVB consists of ca. 10(6) km(3) of volcanic rocks. At 106-105 Ma, subduction-related magmatism initiated in the southern and central segments of the OCVB. In the Central and Northern Chukotka areas, where the northern OCVB is exposed, onset of arc magmatism occurred ca. 10 m.y. after extension-related magmatism of the Chaun igneous province at 109-104 Ma. Mafic rocks from the OCVB yield (Sr-87/Sr-86)(80) (Ma) of 0.7033 to 0.7047, epsilon Nd-80 (Ma) of 0.0 to 7.10, epsilon Hf-80 (Ma) of 4.12 to 12.88, ((206)pw(204)pb)(80 Ma) of 18.11 to 18.42, and ((208)pb/(204)pb)(80 Ma) of 37.96 to 38.21. Volcanic rocks from the Chaun province, as well as OCVB rocks from Northern Chukotka, originate from a relatively enriched source and have (Sr-87/Sr-86)(80) (Ma) of 0.7088 to 0.7100, epsilon Nd-80 (Ma) of -5.81 to -3.42, epsilon Hf-80 (Ma) of -3.40 to -0.25, ((206)pb/(204)pb)(80 Ma) of 18.69 to 18.90, and ((208)pb/(204)pb)(80 Ma) of 38.65 to 38.86. No definitive across-arc elemental or isotopic zonation of the OCVB has been revealed, probably because of wide-scale crustal melting and subsequent contamination of mantle-derived melts. However, there is a clear along-arc isotopic zonation. In our interpretation, this results from heterogeneity of the subcontinental lithospheric mantle, which likely was a major contributor to the magma source. The similar isotopic signatures of silicic (dominantly crust-derived) and mafic (mantle-derived) volcanic rocks in each OCVB segment imply that remelting of juvenile mafic underplated material was the main process responsible for the crust-derived magma generation. These data from the major Cretaceous magmatic provinces of northeast Asia are synthesized in context of existing plate tectonic reconstructions. (C) 2016 Elsevier B.V. All rights reserved:

DOI： 10.1016/j.lithos.2016.08.009

High-resolution MC-ICPMS employing amplifiers with a 10 ¹² ohm resistor for bulk sulfur determination in biological and geological samples 査読

Akio Makishima, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 27 ( 5 ) 891 - 895 2012年5月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

The analytical performance of high-resolution multiple-collector inductively coupled plasma mass spectrometry (HR-MC-ICPMS), employing amplifiers with a 10(12) ohm resistor, was examined. HR-MC-ICPMS showed 50 times higher detection efficiency and 100 times better precision for sulfur and S-34/S-32 than the single-collector high-resolution sector field type ICPMS (HR-ICP-SFMS). The 3 sigma detection limits for S-32 and S-34 were 0.2 and 6 ng mL(-1), respectively. No matrix effects were observed, for up to 3000 mu g g(-1) of total dissolved solids (TDS), within 0.6% error. Thus when the isotope dilution (ID) technique is utilized, this method allows analyses of sulfur concentration of seven times smaller, with six times better precision, than the HR-ICP-SFMS methods. To demonstrate the applicability of this ID-HR-MC-ICPMS method, bulk sulfur concentrations in bovine serum albumin, human serum, eight silicate reference materials (JB-2, JB-3, JA-2, JA-3, JP-1, BCR-2, BHVO-1 and AGV-1), and four carbonaceous chondrites (Murchison, Allende, Dal al Gani 521 and 194) were measured.

DOI： 10.1039/c2ja10337k

The Cretaceous Okhotsk-Chukotka Volcanic Belt (NE Russia): Geology, geochronology, magma output rates, and implications on the genesis of silicic LIPs 査読

P. L. Tikhomirov, E. A. Kalinina, T. Moriguti, A. Makishima, K. Kobayashi, Yu I. Cherepanova, E. Nakamura

Journal of Volcanology and Geothermal Research 221-222 14 - 32 2012年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

The Cretaceous Okhotsk-Chukotka volcanic belt (OCVB) is a prominent subduction-related magmatic province, having the remarkably high proportion of silicic rocks (ca. 53% of the present-day crop area, and presumably over 70% of the total volcanic volume). Its estimated total extrusive volume ranges between 5.5×10 5km 3 (the most conservative estimate) and over 10 6km 3. This article presents a brief outline of the geology of OCVB, yet poorly described in international scientific literature, and results of a geochronological study on the northern part of the volcanic belt. On the base of new and published U-Pb and 40Ar/ 39Ar age determinations, a new chronological model is proposed. Our study indicates that the activity of the volcanic belt was highly discontinuous and comprised at least five main episodes at 106-98Ma, 94-91Ma, 89-87Ma, 85.5-84Ma, and 82-79Ma. The new data allow a semi-quantitative estimate of the volcanic output rate for the observed part of the OCVB (area and volume approximately 10 5km 2 and 2.5×10 5km 3, respectively). The average extrusion rate for the entire lifetime of the volcanic belt ranges between 1.6 and 3.6×10 -5km 3yr -1km -1, depending on the assumed average thickness of the volcanic pile; the optimal value is 2.6×10 -5km 3yr -1km -1. Despite imprecise, such estimates infer the time-averaged volcanic productivity of the OCVB is similar to that of silicic LIPs and most active recent subduction-related volcanic areas of the Earth. However, the most extensive volcanic flare-ups at 89-87 and 85.5-84Ma had higher rates of over 9.0×10 -5km 3yr -1km -1.The main volumetric, temporal and compositional parameters of the OCVB are similar to those of silicic LIPs. This gives ground for discussion about the geodynamic setting of the latters, because the widely accepted definition of a LIP implies a strictly intraplate environment. Considering the genesis of the OCVB and other large provinces of silicic volcanism, we propose that residual thermal energy preserved in the continental crust after a previous major magmatic event may have been one of major reasons for high proportion of felsic rocks in a volcanic pile. In this scenario, underplating of mantle-derived basalts causes fast and extensive melting of still hot continental crust and generation of voluminous silicic magmas. © 2011 Elsevier B.V.

DOI： 10.1016/j.jvolgeores.2011.12.011

Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft 査読

Eizo Nakamura, Akio Makishima, Takuya Moriguti, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Tatsuki Tsujimori, Chie Sakaguchi, Hiroshi Kitagawa, Tsutomu Ota, Yusuke Yachi, Toru Yada, Masanao Abe, Akio Fujimura, Munetaka Ueno, Toshifumi Mukai, Makoto Yoshikawa, Jun'ichiro Kawaguchi

Proceedings of the National Academy of Sciences of the United States of America 109 ( 11 ) E624 - E629 2012年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATL ACAD SCIENCES

Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed. Chemical and O isotope compositions of five lithic grains, with diameters near 50 mu m, indicate that the uppermost layer of the rubble-pile-textured Itokawa is largely composed of equilibrated LL-ordinary-chondrite-like material with superimposed effects of collisions. The surfaces of the grains are dominated by fractures, and the fracture planes contain not only sub-mu m-sized craters but also a large number of sub-mu m-to several-mu m-sized adhered particles, some of the latter composed of glass. The size distribution and chemical compositions of the adhered particles, together with the occurrences of the sub-mu m-sized craters, suggest formation by hypervelocity collisions of micrometeorites at down to nm scales, a process expected in the physically hostile environment at an asteroid's surface. We describe impact-related phenomena, ranging in scale from 10(-9) to 10(4) meters, demonstrating the central role played by impact processes in the long-term evolution of planetary bodies. Impact appears to be an important process shaping the exteriors of not only large planetary bodies, such as the moon, but also low-gravity bodies such as asteroids.

DOI： 10.1073/pnas.1116236109

Simultaneous Determination of Cd, In, Tl and Bi by Isotope Dilution-Internal Standardisation ICP-QMS with Corrections Using Externally Measured MoO⁺/Mo⁺ Ratios 査読

Akio Makishima, Hiroshi Kitagawa, Eizo Nakamura

Geostandards and Geoanalytical Research 35 ( 1 ) 57 - 67 2011年3月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY

A method for the simultaneous determination of Cd with In, Tl and Bi by isotope dilution-internal standardisation (ID-IS) ICP-QMS using the same aliquot for rare earth element and other trace element determinations was developed. Samples mixed with an enriched 149Sm spike were decomposed using a HF-HClO4 mixture, which was evaporated and then diluted with HNO3. After determination of Sm by ID-ICP-QMS and Cd, In, Tl and Bi concentrations were determined using the 149Sm intensity as an internal standard. The interference of MoO+ on Cd+ was corrected using the MoO+/Mo+ ratio separately measured using a Mo standard solution, and the validity of the externally determined oxide-forming ratio correction was evaluated. The MoO+/Mo+ ratios measured using the standard solution and samples were similar to 0.0002 and < 0.002, respectively. Detection limits for Cd, In, Tl and Bi in silicate samples were at levels of < 1 ng g-1 with a total uncertainty of < 7%. Cadmium in the carbonaceous chondrites, Orgueil (CI1), Murchison (CM2) and Allende (CV3) as well as Cd, In, Tl and Bi in the reference materials, JB-2, JB-3, JA-1, JA-2, JA-3, JP-1 (GSJ), BHVO-1, AGV-1, PCC-1 and DTS-1 (USGS) and NIST SRM 610, 612, 614 and 616 were determined to show the applicability of this method.Une methode pour la determination simultanee du Cd avec l'In, le Tl et le Bi par dilution isotopique a standardisation interne (ID-IS) ICP-QMS utilisant le meme aliquot pour la determination des terres rares et d'autres elements traces a ete developpe. Les echantillons melanges avec un ajout (' spike ') enrichi en 149Sm ont ete decomposes en utilisant un melange HF-HClO4, qui a eteevapore et, enfin, dilue avec HNO3. Apres la determination du Sm par ID-ICP-QMS, les concentrations en Cd, In, Tl et Bi ont ete determinees en utilisant l'intensite du 149Sm comme standard interne. L'interference de MoO+ sur Cd+ a ete corrige en utilisant le rapport MoO+/Mo+ mesure separement a l'aide d'une solution de Mo standard, et la validite de cette correction a eteevalue. Les rapports MoO+/Mo+ mesures a l'aide des solutions standards et des echantillons ont ete respectivement d'environ 0.0002 et inferieurs a 0.002. Les limites de detection pour le Cd, l'In, le Tl et le Bi dans les echantillons de silicate ont etea des niveaux inferieurs a 1 ng g-1 avec une incertitude totale inferieure a 7%. Le cadmium dans les chondrites carbonees : Orgueil (CI1), Murchison (CM2) et Allende (CV3) ainsi que le Cd, l'In, le Tl et le Bi dans les materiaux de reference : JB-2, JB-3, JA-1, JA-2, JA-3, JP-1 (GSJ), BHVO-1, AGV-1, PCC-1, DTS-1 (USGS) et NIST SRM 610, 612, 614 et 616 ont ete determines afin de demontrer l'applicabilite de cette methode.

DOI： 10.1111/j.1751-908X.2010.00054.x

Precise isotopic determination of Hf and Pb at sub-nano gram levels by MC-ICP-MS employing a newly designed sample cone and a pre-amplifier with a 10¹² ohm register 査読

Akio Makishima, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 25 ( 11 ) 1712 - 1716 2010年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Precise isotopic determination methods for Hf and Pb at sub-nano gram levels have been undertaken for this contribution utilizing the Neptune multiple collector ICP-MS (MC-ICP-MS) with a newly designed sample cone (the Jet cone) and a new pre-amplifier with a highly-resistive register of 1012 ohm. The Jet cone enhanced sensitivities 1.6 and 3 times for Hf and Pb, respectively. The Jet cone showed no significant improvements in reproducibility of Hf isotope analysis at >1 ng compared to the normal cone, but the reproducibility improved considerably by half when Hf concentration of <1 ng was measured. Thus, 0.3 and 0.8 ng of Hf can yield reproducibility (2SD in epsilon-unit) of 3 and 1.7, respectively. Reproducibility (RSD) of Pb-207/Pb-206, Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 were 0.026, 0.28, 0.33 and 0.36% using total Pb of 0.025 ng, and 0.02, 0.10, 0.10 and 0.08% using 0.05 ng, respectively. Thus, the Jet cone with the new pre-amplifier showed the best performance compared to the normal cone and pre-amplifier and are similar or even better than those obtained by the Pb-202-Pb-205 double-spike TIMS or multi-ion counting ICP-MS techniques.

DOI： 10.1039/c0ja00015a

Chromium isotope systematics of achondrites: Chronology and isotopic heterogeneity of the inner solar system bodies 査読

Akane Yamakawa, Katsuyuki Yamashita, Akio Makishima, Eizo Nakamura

Astrophysical Journal 720 ( 1 ) 150 - 154 2010年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IOP PUBLISHING LTD

The standard planetary formation models assume that primitive materials, such as carbonaceous chondrites, are the precursor materials of evolved planetesimals. Past chronological studies have revealed that planetesimals of several hundred kilometers in size, such as the Howardite-Eucrite-Diogenite (HED) parent body (Vesta) and angrite parent body, began their differentiation as early as similar to 3 million years of the solar system formation, and continued for at least several million years. However, the timescale of planetesimal formation in distinct regions of the inner solar system, as well as the isotopic characteristics of the reservoirs from which they evolved, remains unclear. Here we present the first report for the precise (53)Mn-(53)Cr ages of monomict ureilites. Chemically separated phases from one monomict ureilite (NWA 766) yielded the Mn-Cr age of 4564.60 +/- 0.67 Ma, identical within error to the oldest age preserved in other achondrites, such as angrites and eucrites. The (54)Cr isotopic data for this and seven additional bulk ureilites show homogeneous epsilon(54)Cr of similar to-0.9, a value distinct from other achondrites and chondrites. Using the epsilon(54)Cr signatures of Earth, Mars, and Vesta (HED), we noticed a linear decrease in the epsilon(54)Cr value with the heliocentric distance in the inner region of the solar system. If this trend can be extrapolated into the outer asteroid belt, the epsilon(54)Cr signatures of monomict ureilites will place the position of the ureilite parent body at similar to 2.8 AU. These observations imply that the differentiation of achondrite parent bodies began nearly simultaneously at similar to 4565 Ma in different regions of the inner solar system. The distinct epsilon(54)Cr value between ureilite and carbonaceous chondrite also implies that a genetic link commonly proposed between the two is unlikely.

DOI： 10.1088/0004-637X/720/1/150

Determination of Fluorine and Chlorine by Pyrohydrolysis and Ion Chromatography: Comparison with Alkaline Fusion Digestion and Ion Chromatography 査読

Qiaoyun Wang, Akio Makishima, Eizo Nakamura

Geostandards and Geoanalytical Research 34 ( 2 ) 175 - 183 2010年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY

A method to determine F and Cl in silicate materials by employing pyrohydrolysis and ion chromatography (IC) is described. Pyrohydrolysis involved mixing a pulverised sample (similar to 40 mg) with V2O5 (similar to 160 mg) and heating to 1100 degrees C under a wet oxygen flow in a quartz tube. Recovery yields of F and Cl were similar to 97% using a NaF + NaCl standard solution. Detection limits of the pyrohydrolysis-IC method for silicate samples were 0.36 and 0.69 mu g g-1 for F and Cl, respectively. Fluorine and Cl concentrations were determined in the reference materials JB-2, JB-3 and JA-1 from the GSJ; BCR-2, BHVO-1, BHVO-2, AGV-1 and AGV-2 from the USGS; and NIST SRM 610, 612 and 614 glasses. Precisions (RSD) for determinations of F were 1-13% (except NIST SRM 614) and 2-19% for Cl, and were dependent on the concentration and blank correction. Most results obtained in this study were in good agreement with those of previous studies. In comparison, the Na2CO3 + ZnO fusion method at 900 degrees C showed that the yields of F and Cl by alkaline fusion systematically decreased with fusion duration time. The yields were 84% and 83% for JB-3, inferring that F and Cl were lost in this alkaline fusion.Une methode de determination des teneurs en F et Cl des materiaux silicates par pyrohydrolyse et chromatographie ionique (CI) est decrite. La pyrohydrolyse implique le melange entre un echantillon pulverise (similar to 40 mg) et du V2O5 (similar to 160 mg) et un chauffage a 1100 degrees C sous un flux d'oxygene humide dans un tube de quartz. Les rendements du F et du Cl ont ete d'environ 97% en utilisant une solution standard de NaF + NaCl. Les limites de detection de la methode CI-pyrohydrolyse pour les echantillons silicates ont ete respectivement de 0.36 et 0.69 mu g g-1 pour F et Cl. Les concentrations en F et Cl ont ete determinees dans les materiaux de reference JB-2, JB-3 et JA-1 du GSJ; BCR-2, BHVO-1, BHVO-2, AGV-1 et AGV-2 de l'USGS, et dans les verres de reference NIST SRM 610, 612 et 614. Les precisions (RSD) pour les determinations du F ont variees entre 1 et 13% (sauf pour le NIST SRM 614) et entre 2 et 19% dans le cas de celles du Cl. Elles dependent de la concentration et de la correction du blanc. La plupart des resultats obtenus dans cette etude sont en bon accord avec ceux des etudes precedentes. En comparaison, la methode de fusion utilisant le couple Na2CO3 + ZnO a 900 degrees C montre que les rendements de F et Cl par fusion alcaline diminuent systematiquement avec la duree de fusion. Les rendements ont ete respectivement de 84 et 83% pour JB-3, ce qui sous entend une perte de F et de Cl durant cette fusion alcaline.

DOI： 10.1111/j.1751-908X.2010.00043.x

Precise elemental and isotopic analyses in silicate samples employing ICP-MS: Application of hydrofluoric acid solution and analytical techniques 招待査読

Akio Makishima, Ryoji Tanaka, Eizo Nakamura

Analytical Sciences 25 ( 10 ) 1181 - 1187 2009年10月

記述言語：英語出版者・発行元：JAPAN SOC ANALYTICAL CHEMISTRY

In this review, a new classification of elements based on behavior in hydrofluoric acid (HF) solution is presented for the precise quantitative analysis of each element by inductively coupled plasma mass spectrometry (ICP-MS). The elements are divided into 7 groups: (1) "fluorophile" elements; (2) insoluble fluoride-forming elements; (3) "bromophile" or "iodophile" elements; (4) "oxophile" elements; (5) "aquaphile" elements; (6) bare cation elements; and (7) other elements. Especially, the importance of fluorophile and insoluble fluoride-forming elements in elemental analysis is described. Due to the elemental characteristics, these two groups of elements cannot be dissolved simultaneously in the same solution, and thus cannot be measured together. In addition, coprecipitation of the fluorophile elements with the insoluble fluorides occurs in some conditions and hinders accurate analysis. The peculiar conditions when the coprecipitation occurs are discussed, and the "Al-addition" and "Mg-addition" methods for overcoming these problems are described. In addition, some state-of-the-art analytical techniques in ICP-MS are shown, and future directions of the element analysis are presented.

DOI： 10.2116/analsci.25.1181

Determination of Ge, As, Se and Te in silicate samples using isotope dilution-internal standardisation octopole reaction cell ICP-QMS by normal sample nebulisation 査読

Akio Makishima, Eizo Nakamura

Geostandards and Geoanalytical Research 33 ( 3 ) 369 - 384 2009年9月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY

A method for the determination of Ge, As, Se and Te in silicate samples using isotope dilution-internal standardisation (ID-IS) octopole reaction cell (ORC) ICP-QMS by normal sample nebulisation was developed. The method does not involve either hydride generation or ion exchange. Germanium, Se and Te were determined by isotope dilution (ID), and As was determined by ID-IS. A silicate sample with an added Ge-Se-Te spike was digested with an HF-HNO3-HBr mixture, dried, re-dissolved with HF and the supernatant liquid was directly aspirated into an ORC-ICP-QMS instrument with He or H-2 gas. No matrix effects were observed down to a dilution factor (DF) of similar to 70 for Ge, Se and Te and DF of similar to 1000 for As, which resulted in 3s detection limits in silicates of 2, 1, 0.1 and 4 ng g-1, respectively. Advantages of the method are the simple sample introduction as well as a capability of determining S, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by ID-IS-ICP-QMS/SFMS from the same solution. Furthermore, the total sample solution consumption was only 0.253 ml with DF = 2000. Therefore, only a 0.13 mg test portion was required. To demonstrate the applicability of this technique, Ge, As, Se and Te in eight silicate reference materials were determined, as well as S, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta in four carbonaceous chondrites.

DOI： 10.1111/j.1751-908X.2009.00014.x

Accumulation of radium in ferruginous protein bodies formed in lung tissue: Association of resulting radiation hotspots with malignant mesothelioma and other malignancies 査読

Eizo Nakamura, Akio Makishima, Kyoko Hagino, Kazunori Okabe

Proceedings of the Japan Academy Series B: Physical and Biological Sciences 85 ( 7 ) 229 - 239 2009年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN ACAD

While exposure to fibers and particles has been proposed to be associated with several different lung malignancies including mesothelioma, the mechanism for the carcinogenesis is not fully understood. Along with mineralogical observation, we have analyzed forty-four major and trace elements in extracted asbestos bodies (fibers and proteins attached to them) with coexisting fiber-free ferruginous protein bodies from extirpative lungs of individuals with malignant mesothelioma,. These observations together with patients' characteristics suggest that inhaled iron-rich asbestos fibers and dust particles, and excess iron deposited by continuous cigarette smoking would induce ferruginous protein body formation resulting in ferritin aggregates in lung tissue. Chemical analysis of ferruginous protein bodies extracted from lung tissues reveals anomalously high concentrations of radioactive radium, reaching millions of dines higher concentration than that of seawater. Continuous and prolonged internal exposure to hotspot ionizing radiation from radium and its daughter nuclides could cause strong and frequent DNA damage in lung tissue, initiate different types of tumour cells, including malignant mesothelioma cells, and may cause cancers.

DOI： 10.2183/pjab.85.229

Comprehensive analysis for major, minor and trace element contents and Sr-Nd-Pb-Hf isotope ratios in sediment reference materials, JSd-1 and MAG-1 査読

B. Nagender Nath, Akio Makishima, Janine Noordmann, Ryoji Tanaka, Eizo Nakamura

Geochemical Journal 43 ( 3 ) 207 - 216 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：GEOCHEMICAL SOC JAPAN

In view of the requirement of a well-characterized and easily available aquatic sediment reference material, a comprehensive analysis comprising of fifty major, minor and trace elements as well as Sr-Nd-Pb-Hf isotopes were carried out in the stream sediment reference material, JSd-1, issued by the Geological Survey of Japan. The data for marine sediment reference material, MAG-1, issued by U.S. Geological Survey is also obtained for comparison. The elements were divided into two groups: Group I and Group II. Elements in Group I form stable soluble ions in HNO3; and those in Group II form soluble oxo- and fluoro-complexes in HF, such as Zr, Nb, Hf, Ta, etc. For Group I, the sample was decomposed with HF in a tetra fluoro ethylene (TFE) bomb at 245 degrees C for 96 hrs with Mg addition. The elemental concentration was measured by quadrupole type inductively coupled plasma source mass spectrometry (ICP-QMS) and sector field type ICP-MS (ICP-SFMS) using isotope dilution-internal standardization (ID-IS) methods. The aliquot of the sample solution was passed through 3-step column chemistry for isotope ratio determination of Pb by Multiple collector (MC) ICP-MS and thermal ionization mass spectrometry (TIMS), and Sr and Nd by TIMS. For Group II elements, the sample was decomposed with H F in a TFE bomb with the same time and temperature settings. Zr, Mo, Sn, Sb and Hf were determined by I D, and Nb and Ta by ID-IS using ICP-QMS. The original JSd-1 powder showed heterogeneity for Group II elements, indicating insufficient pulverization and distribution. Thus, we further pulverized the powder and measured the concentration, which showed improved homogeneity. The aliquot for the re-pulverized powder was passed through 2-step column chemistry, and the Hf isotope ratio was determined by MC-ICP-MS. Thus a new data on the trace elements as well as Sr-Nd-Pb-Hf isotope ratios is provided for JSd-1 and MAG-1 in this paper.

DOI： 10.2343/geochemj.1.0018

Highly unradiogenic lead isotope ratios from the horoman peridotite in japan 査読

Sanjeewa P.K. Malaviarachchi, Akio Makishima, Masaaki Tanimoto, Takeshi Kuritani, Eizo Nakamura

Nature Geoscience 1 ( 12 ) 859 - 863 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Basalts at mid-ocean ridges are generated by partial melting of the Earth's upper mantle. As a result of this process, the upper mantle has become depleted over time in elements that are preferentially removed by melting(1-3). Although mid-ocean-ridge basalts have traditionally been thought to reflect the chemical composition of such depleted mantle(2-7), recent work has revealed the existence of domains in the upper mantle that are apparently not sampled by the basalts(8). Here we present the lead (Pb), neodymium (Nd) and hafnium (Hf) isotope compositions of peridotites from the Horoman orogenic massif in Japan, which is considered to represent the residues of melting of the upper mantle. These peridotites exhibit the lowest Pb isotope ratios reported from any known mantle material, along with high Nd and Hf isotope ratios. These data suggest that chemical depletion of the peridotites occurred around a billion years ago, and that they represent ancient mantle domains that have escaped convective stirring and homogenization. We suggest that such domains-if abundant in the mantle-may constitute a hitherto unrecognized reservoir with highly unradiogenic lead.

DOI： 10.1038/ngeo363

Multiple pulses of the mantle plume: Evidence from tertiary icelandic lavas 査読

Hiroshi Kitagawa, Katsura Kobayashi, Akio Makishima, Eizo Nakamura

Journal of Petrology 49 ( 7 ) 1365 - 1396 2008年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OXFORD UNIV PRESS

We present major and trace element concentrations and Sr-Nd-Hf-Pb isotope data for the c. 13-2 Ma Tertiary lavas from eastern Iceland. Our new geochemical results, together with published geological, geochronological, geochemical and geophysical data, are used to evaluate temporal changes in mantle sources contributing to the Tertiary Icelandic magmatism and the relative roles of these sources in magma productivity. The trace element and radiogenic isotopic compositions clearly distinguish three distinct end-member components in the Tertiary magmatism. Temporal variations in lava geochemistry can be attributed to changes in the relative contributions of these three end-member components to the erupted magmas and correlated with temporal variations in magma productivity. The extrusion of lavas with geochemically and isotopically enriched compositions was particularly pronounced at similar to 13-12 and 8-7 Ma, coincident in time with higher magma productivity. However, the geochemical characteristics of the lavas are different during these two periods: the 13-12 Ma lavas have more radiogenic Hf-176/Hf-177 and less radiogenic Pb-206/Pb-204 than those erupted from 8 to 7 Ma. The eruption of relatively depleted lavas, at around 10 Ma and younger than 6.5 Ma, is coincident with lower magma productivity. The correlation between the composition and productivity of the Tertiary lavas from eastern Iceland is probably due to periodic changes in the involvement of the enriched end-member component, followed by a gradation to periods dominated by the signature of the depleted end-member component and lower magma productivity, at an approximate frequency of 5 Myr.

DOI： 10.1093/petrology/egn029

Hawaiian double volcanic chain triggered by an episodic involvement of recycled material: Constraints from temporal Sr-Nd-Hf-Pb isotopic trend of the Loa-type volcanoes 査読

Ryoji Tanaka, Akio Makishima, Eizo Nakamura

Earth and Planetary Science Letters 265 ( 3-4 ) 450 - 465 2008年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER

The two parallel loci of recent Hawaiian volcanoes, Kea and Loa, have been regarded as the best targets to interpret the chemical structure of an upwelling mantle plume derived from the lower mantle. Here we show that the Sr-Nd-Hf-Pb isotopic data of the shield-building lavas along the Loa locus form a systematic trend from the main shield stage of Koolau (>2.9 Ma) to the active Loihi volcanoes. During the growth of the Koolau volcano, the dominant material in the melting region successively changed from the proposed KEA, DMK (depleted Makapuu), to EMK (enriched Makapuu) components. The proportion of EMK, dominated by a recycled mafic component, is typified by some Koolau Makapuu-stage and some Lanai lavas. Subsequently, the EMK component decreased and LOIHI component increased toward the Loihi lavas. The temporal coincidence between the episodically elevated magma production rate and the abrupt appearance of the typical Loa-type lavas that is restricted to the last 3 Myr should be linked to magma genesis. We suggest that the abrupt appearance of Loa-type magmatism should be attributed to the transient incorporation of the relatively dense recycled material and surrounding less degassed lower mantle material that accumulated near the core-mantle boundary into the upwelling plume. This episodic involvement could have been trigged by episodic thermal pulses and buoyancy increases in the plume. The continuous appearance of Kea-type lavas during the long history of Hawaiian-chain magmatism and the larger magma volume of Kea-type lavas relative to that of the Loa-type lavas in the last 3 Myr indicate that the Kea locus is closer to the thermal centre of the Hawaiian plume relative to that of the Loa locus. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2007.10.035

New sequential separation procedure for Sr, Nd and Pb isotope ratio measurement in geological material using MC-ICP-MS and TIMS 査読

Akio Makishima, B. Nagender Nath, Eizo Nakamura

Geochemical Journal 42 ( 3 ) 237 - 246 2008年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：GEOCHEMICAL SOC JAPAN

A new 3-step sequential separation chemistry for Sr, Nd and Pb from silicate samples, which is suitable for isotope analysis by MC-ICP-MS as well as TIMS, has been developed. The chemistry is designed to minimize the number of evaporation steps, enabling high throughput especially when MC-ICP-MS is employed. The sample solution in 0.5 mol 1(-1) HNO3 after digestion with HF-HCIO4, which is prepared for trace element analysis, can be directly used in the new chemistry. In the first column using Sr resin, Sr and Pb are collected. The recovered solution for Sr can be directly aspirated into MC-ICP-MS. The Pb solution is dried, re-dissolved, separated into two aliquots and measured by double spike MC-ICP-MS. Subsequently, LREEs are collected by the second column packed with cation exchange resin. Finally, Nd was purified from Sm using Ln resin in the third column. The recovered Nd solution can also be directly nebulized into MC-ICP-MS. The Sr and Nd isotope ratios for the standard material JB-3 (basalt) from the Geological Survey of Japan by MC-ICP-MS and TIMS were reported to verify the chemistry and mass spectrometry developed in this study.

DOI： 10.2343/geochemj.42.237

New preconcentration technique of Zr, Nb, Mo, Hf, Ta and W employing coprecipitation with Ti compounds: Its application to Lu-Hf system and sequential Pb-Sr-Nd-Sm separation 査読

Akio Makishima, Eizo Nakamura

Geochemical Journal 42 ( 2 ) 199 - 206 2008年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：GEOCHEMICAL SOC JAPAN

A new preconcentration technique of Zr, Nb, Mo, Hf, Ta and W has been invented employing coprecipiation with Ti compounds. Silicate samples were digested by HF with addition of Ti. Subsequent drying with HClO4 resulting in complete elimination of fluorine produces Ti compounds (oxide/hydroxides). The sample was then dissolved with dilute nitric acid and centrifuged, and the residual Ti compounds were collected. The Ti compounds forming from 2 mg of Ti without matrix elements concentrate 84-98% of Zr, Nb, Mo, Hf, Ta and W. In 20 mg basaltic and 50 mg peridotitic matrices, the addition of I nig of Ti was appropriate and gave yields of 46-69 and 54-79%, respectively, for Zr, Nb, Mo, Hf, Ta and W. Exploiting this preconcentration, sequential separation protocols of Hf, Pb, Sr, Lu, Nd and Sm for isotope analysis are developed with total blanks of 16, 11, 60, 2.4, 3 and 0.4 pg, respectively. The method is suitable for Lu-Hf system studies with capability of simultaneous separation of Pb, Sr, Nd and Sm from the same sample digest as well as isotopic anomaly studies of Zr, Mo and W. As application examples, accurate Lu-Hf data and Pb isotope ratios were obtained for basalt (JB-3) and peridotite (JP-1) by MC-ICP-MS.

DOI： 10.2343/geochemj.42.199

Precise measurement of ²²⁸Ra/²²⁶Ra for ²²⁶Ra determination employing total integration and simultaneous ²²⁸Th correction by multicollector ICP-MS using multiple ion counters 査読

Akio Makishima, Takele A. Chekol, Eizo Nakamura

Journal of Analytical Atomic Spectrometry 23 ( 8 ) 1102 - 1107 2008年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

A precise method of measuring Ra-228/Ra-226 for Ra-226 determination used in U-series disequilibrium studies has been developed using the total integration method with simultaneous 228Th isobaric interference correction by multicollector ICP- MS with multiple ion counters (MIC). A sample solution of 0.2 ml was separately taken into a test tube, and all Ra-226(+) and Ra-228(+) signals as well as Th-229(+) and (ThO+)-Th-228-O-16 from beginning to end were integrated simultaneously using four channeltrons, IC1, IC3, IC4 and IC5, respectively. Gains between IC1 and IC3 and the mass discrimination factor for Ra-228/ (226) Ra determination were canceled out by measurement of a Ra spike solution with an accurately known Ra isotope ratio determined by TIMS, with which samples were bracketed. The isobaric interferences of Th-228(+) were simultaneously corrected from the signal of (ThO+)-Th-228-O-16 and the oxide forming ratio of Th-228, which was separately determined by simultaneous measurements of Th-229(+) and 2(29)Th(16)O(+) by IC3 and IC5. The gains between IC3 and IC5 for the Th correction were also canceled out. The ion yield of Ra in MIC- ICP- MS was similar to 1.5%. The intermediate precision using 6.6, 3.3, 1.7, 0.83 and 0.41 fg of Ra-226 with Ra-228/Ra-226 similar to 5 was 0.33, 0.93, 0.76, 1.6 and 1.5%, respectively. The Ra-228/Ra-226 ratio showed no systematic change dependent on Th-228/Ra-228 up to 0.25, indicating the validity of the Th-228 correction. At similar amounts of Ra, our method gives intermediate precision values similar to or better than previous MC-ICP-MS and TIMS studies. The precision of the method was verified using another Ra spike with Ra-228/ Ra-226 = similar to 1 determined by TIMS. The analytical performance of the method was further investigated using the silicate samples JB-2 and JB-3 basalts issued by GSJ.

DOI： 10.1039/b807431c

Ancient recycled crust beneath the Ontong Java Plateau: Isotopic evidence from the garnet clinopyroxenite xenoliths, Malaita, Solomon Islands 査読

Akira Ishikawa, Takeshi Kuritani, Akio Makishima, Eizo Nakamura

Earth and Planetary Science Letters 259 ( 1-2 ) 134 - 148 2007年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER

We present a Sr, Nd, Hf and Pb isotope investigation of a set of garnet clinopyroxenite xenoliths from Malaita, Solomon Islands in order to constrain crustal recycling in the Pacific mantle. Geological, thermobarometric and petrochemical evidence from previous studies strongly support an origin as a series of high-pressure (> 3 GPa) melting residues of basaltic material incorporated in peridotite, which was derived from Pacific convective mantle related to the Ontong Java Plateau magmatism. The present study reveals isotopic variations in the pyroxenites that are best explained by different extents of chemical reaction with ambient peridotite in the context of a melting of composite source mantle. Isotopic compositions of bimineralic gamet clinopyroxenites affected by ambient peridotite fall within the oceanic basalt array, similar to those of Ontong Java Plateau lavas. In contrast, a quartz-gaenet clinopyroxenite, whose major element compositions remain intact, has lower Pb-206/(204) Pb-Nd-143/(144) Nd and higher (87)sr/Sr-86-Pb-207/(204) Pb ratios than most oceanic basalts. These isotopic signatures show some affinity with proposed recycled sources such as the so-called EM-1 or DUPAL types. Constraints from major and trace element characteristics of the quartz-garnet clinopyroxenite, the large extent of Hf-Nd isotopic decoupling and the good coincidence of Ph isotopes to the Stacey-Kramers curve, all indicate that pollution of southern Pacific mantle occurred by the subduction or delamination of Neoproterozoic granulitic lower crust (0.5-1 Ga). This crustal recycling could have taken place around the suture of Rodinia supercontinent, a part of which resurfaced during mantle upwelling responsible for creating the Cretaceous Ontong Java Plateau. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2007.04.034

Coprecipitation of Ti, Mo, Sn and Sb with fluorides and application to determination of B, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by ICP-MS 査読

Yinghuai Lu, Akio Makishima, Eizo Nakamura

Chemical Geology 236 ( 1-2 ) 13 - 26 2007年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER

We examined the coprecipitation behavior of Ti, Mo, Sn and Sb in Ca-Al-Mg fluorides under two different fluoride forming conditions: at < 70 degrees C in an ultrasonic bath (denoted as the ultrasonic method) and at 245 degrees C using a Teflon bomb (denoted as the bomb method). In the ultrasonic method, small amounts of Ti, Mo and Sn coprecipitation were observed with 100% Ca and 100% Mg fluorides. No coprecipitation of Ti, Mo, Sn and Sb in Ca-Al-Mg fluorides occurred when the sample was decomposed by the bomb method except for 100% Ca fluoride. Based on our coprecipitation observations, we have developed a simultaneous determination method for B, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by Q-pole type ICP-MS (ICP-QMS) and sector field type ICP-MS (ICP-SFMS). 9-50 mg of samples with Zr-Mo-Sn-Sb-Hf spikes were decomposed by HF using the bomb method and the ultrasonic method with B spike. The sample was then evaporated and re-dissolved into 0.5 mol FI HF, followed by the removal of fluorides by centrifuging. B, Zr, Mo, Sn, Sb and Hf were measured by ID method. Nb and Ta were measured by the ID-internal standardization method, based on Nb/Mo and Ta/Mo ratios using ICP-QMS, for which pseudo-FI was developed and applied. When 100% recovery yields of Zr and Hf are expected, Nb/Zr and TAW ratios may also be used. Ti was determined by the ID-internal standardization method, based on the Ti/Nb ratio from ICP-SFMS. Only 0.053 ml sample solution was required for measurement of all 9 elements. Dilution factors of <= 340 were aspirated without matrix effects. To demonstrate the applicability of our method, 4 carbonaceous chondrites (Ivuna, Orgueil, Cold Bokkeveld and Allende) as well as GSJ and USGS silicate reference materials of basalts, andesites and peridotites were analyzed. Our analytical results are consistent with previous studies, and the mean reproducibility of each element is 1.0-4.6% for basalts and andesites, and 6.7-11% for peridotites except for TiO2. (c) 2006 Elsevier B.V All rights reserved.

DOI： 10.1016/j.chemgeo.2006.08.007

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