研究者詳細 - 中村　栄三

MISC - 中村　栄三

分割表示 135 件中 101 - 120 件目／全件表示 >>

Separation of thorium and uranium from silicate rock samples using two commercial extraction chromatographic resins

Yokoyama, T, Makishima, A, Nakamura, E

Analytical Chemistry 1999年

Determination of zirconium, niobium, hafnium and tantalum at ng/g levels in geological materials by direct nebulization of samples HF solution into FI-ICP-MS

Makishima, A, Nakamura, E, Nakano, T

Geostand. Newslett. 1999年

Across-arc variation of Li isotopes in lavas and implications for crust/mantle recycling at subduction zones

Takuya Moriguti, Eizo Nakamura

Earth and Planetary Science Letters 163 ( 1-4 ) 167 - 174 1998年11月

Trace element diffusion in jadeite and diopside melts at high pressures and its geochemical implication

Eizo Nakamura, Ikuo Kushiro

Geochimica et Cosmochimica Acta 62 ( 18 ) 3151 - 3160 1998年9月

記述言語：英語

Diffusivities of geochemically important trace elements (eleven rare earth elements (REE), Rb, Sr, Ba, and Y) in jadeite and diopside melts and those of Zr, Nb, Th, and U in jadeite melt have been measured at pressures between 7.5 and 20 kbar and at temperatures 50-200°above the liquids, using diffusion couples and ion microprobe analysis. The concentrations of these elements in the experimental charges are close to those in natural igneous rocks. In the jadeite melt which is nearly fully polymerized (NBO/T ~ 0), (1) diffusivities of REE increase with increasing ionic radii, (2) diffusivities of tri- and tetravalent elements increase with increasing pressure at constant temperature, whereas those of mono- and divalent elements do not change significantly with pressure, and (3) diffusivities of these elements decrease with increasing their ionic charge at constant pressure and temperature. In the diopside melt which is considerably less polymerized (NBO/T ~ 2), (1) diffusivities of these trace elements depend mainly on their ionic radii rather than ionic charges
the diffusivities of mono- and divalent ions decrease with increasing ionic radii at constant pressure and temperature, and (2) diffusivities of REE are nearly the same as that of Ca and decrease with increasing pressure at constant temperature. The behavior of these trace elements is correlated with that of major elements
in the jadeite melt, tri- and tetravalent elements behave similarly to network-forming cations Al and Si, whereas mono- and divalent elements behave as network-modifying cations similarly to Na. In the diopside melt, the diffusion behavior of all these trace elements is similar to that of network-modifying cations Ca and Mg. The results of the present experiments suggest that the abundance of some trace elements in igneous rocks may have been affected by diffusion process at the magmatic stage. In the case of REE, for example, if two different magmas with high and low REE concentrations become in contact one another by multiple intrusion, and a zoned magma chamber is formed, diffusion begins to take place between them, and near the interface, the REE-enriched magma will become more light REE-depleted, whereas REE-depleted magma will become more light REE-enriched, and in addition, if magmas are reduced, the former will show a negative Eu anomaly, whereas the latter will show a positive Eu anomaly.

DOI： 10.1016/S0016-7037(98)00223-3

Scopus

researchmap

High-yield lithium separation and the precise isotopic analysis for natural rock and aqueous samples

Takuya Moriguti, Eizo Nakamura

Chemical Geology 145 ( 1-2 ) 91 - 104 1998年3月

記述言語：英語出版者・発行元：Elsevier B.V.

A high-yield lithium separation technique for rock and aqueous samples has been established together with precise Li isotope analysis by thermal ionization mass spectrometry. Four separate stages of ion-exchange chromatography were carried out using organic ion-exchange resin. An ethanol-HCl solution was used for complete separation of Li from Na at the third column stage. Total reagent volume for the entire chemical process was reduced to 42 ml and 33.3 ml for rock samples and seawater, respectively. The recovery yield and total procedural blank are 99.2-99.3% and 11 pg, respectively. Li3PO4 was used as an ion-source material in the mass spectrometric analysis. The in-run precision and reproducibility of measured 7Li/6Li ratios were ±0.04-0.07‰ (2σmean) and 0.37‰ (relative standard deviation
RSD) for rock and ±0.05-0.08‰ (2σmean) and 0.35‰ (RSD) for seawater. In this method, Rb, Sr, Sm, Nd, La and Ce can be collected after Li elution in the first column chromatography, then separated by the following specific procedures for these elements. Therefore, this method makes possible multi-isotope analysis for Li-poor and restricted small amounts of samples such as meteorites and mantle materials, extending to Li isotope geochemistry and cosmochemistry. © 1998 Elsevier Science B.V.

DOI： 10.1016/S0009-2541(97)00163-0

Scopus

researchmap

High-yield lithium separation and precise isotopic analysis for natural and aqueous samples

Moriguti, T, Nakamura, E

Chemical Geology 1998年

Trace element diffusion in jadeite and diopside melts at high pressures and its geochemical implication

Nakamura, E, Kushiro, I

Geochim. Cosmochim. Acta 1998年

Across-arc variation of Li isotopes in arc lavas and implications for crust/mantle recycling at subduction zones

Moriguti, T, Nakamura, E

Earth Planet. Sci. Lett. 1998年

Static multicollection of Cs2BO2+ ions for precise boron isotope analysis with positive thermal ionization mass spectrometry

Nakano, T, Nakamura, E

Int. J. Mass Spectrom. Ion Processes 1998年

Inherited Paleozoic and Mesozoic Rb-Sr isotopic signatures in Neogene calc-alkaline volcanics, Alboran volcanic province, SE Spain

Zeck, H.P, Kristensen, A.B, Nakamura, E

J. Petrology 1998年

Diffusivities of rare earth elements and Ba in magmatic silicate melts at high pressures

Eizo Nakamura, Ikuo Kushiro

Proceedings of the Japan Academy Series B: Physical and Biological Sciences 73 ( 3 ) 44 - 47 1997年

記述言語：英語出版者・発行元：Japan Academy

Diffusivities of 11 rare earth elements (REE) and Ba in jadeite (NaAlSi2O6) and diopside (CaMgSi2O6) melts have been measured at pressures between 10 and 20 kbar. In jadeite melt, diffusivities of REE increase regularly with increasing their ionic radii, light REE (e.g., La and Ce) diffuse faster than heavy REE (e.g., Yb and Lu) by about 30%, Eu diffuses faster by factor of 8 to 12 than other REE under reducing conditions, and diffusivities of REE increase with increasing pressure at constant temperature. In diopside melt, diffusivities of REE are nearly the same as that of Ca and decrease with increasing pressure. The present study demonstrates that diffusion process in magma should change the relative abundances of REE and also generate Eu anomalies without involvement of plagioclase feldspar. This diffusion-induced process is a newly recognized mechanism of changing the relative REE abundances in magmas and generating Eu anomalies, and it must be taken into account in interpreting the REE abundance patterns of igneous rocks.

DOI： 10.2183/pjab.73.44

Scopus

researchmap

Suppression of matrix effect in ICP-MS by high power operation of ICP: Application to precise determination of Rb, Sr, Y, Cs, Ba, REE, Pb, Th and U at ng /g level in a few milligram silicate sample

Makishima, A, Nakamura, E

Geostandard Newsletter 1997年

Across-arc variations of isotope and trace element compositions from Quaternary basaltic rocks in northeastern Japan: Implications for interaction between subducted oceanic slab and mantle wedge

Shibata, T, Nakamura, E

Jornal of Geophysical Research 1997年

Mantle process as inferred from trace element and radiogenic isotopic geochemistry of peridotite complexes

Yoshikawa, M, Nakamura, E

Mem. Geol. Soc. Japan 1997年

Diffusivities of rare earth elements and Ba in magmatic melts at high pressure

Nakamura, E, Kushiro I

Proceedings of Japan Academy 1997年

Determination of boron in silicate samples by direct aspiration of sample HF solutions into ICPMS

Makishima, A, Nakamura, E, Nakano T

Analytical Chemistry 1997年

Possible eastward extension of Chinese collision belt in South Korea: The Imjingang belt

Jin-Han Ree, Moonsup Cho, Sung-Tack Kwon, Eizo Nakamura

Geology 24 ( 12 ) 1071 - 1074 1996年12月

記述言語：英語

Structural, petrological, and geochronological data from the middle Korean peninsula indicate that the Qinling-Dabie-Sulu cullisional belt of east-central China crosses the Yellow Sea and extends into the Imjingang belt. The Yeoncheon complex, first identified as the western Imjingang belt, comprises primarily north-dipping metamorphic sequences: (1) the northern Jingok unit, consisting of Harrovian-type metapelites, and (2) the southern Samgot unit, consisting of calc-silicate and amphibolitic rocks. South-vergent structures with reverse-sense shearing are dominant in the Jingok unit, whereas late normal-sense shearing is pervasive in the Samgot unit and the deformed granitoid to the south. These structural patterns are interpreted to correspond to extensional deformation associated with uplift following compression in a collisional belt. Pressure-temperature (P-T) estimates from the amphibolites suggest a high-P amphibolite-facies metamorphism (8-13 kbar and 630-790°C), possibly evolving from eclogite facies conditions along a clockwise P-T path. Sm-Nd and Rb-Sr geochronological data suggest that the amphibolites emplaced in Late Proterozoic time were metamorphosed during Permian-Triassic time.

DOI： 10.1130/0091-7613(1996)024<1071:PEEOCC>2.3.CO;2

Scopus

researchmap

Boron isotope ratios in meteorites and lunar rocks

Mingzhe Zhai, Eizo Nakamura, Denis M. Shaw, Toshio Nakano

Geochimica et Cosmochimica Acta 60 ( 23 ) 4877 - 4881 1996年12月

記述言語：英語

The 11B/10B ratios of thirty-two meteorite falls and nine lunar rocks were measured as Cs2BO+2 using thermal ionization mass-spectrometry. The 11B/10B ratios of meteorites vary from 4.011 to 4.098, i.e., their δ11B values (relative to NIST SRM 951) range from -10.5 to +19.2‰
however, excluding two outliers, Mokoia and Norton County, the range of most meteorites is smaller (-10.5 to +7.5). The average of two CI1 meteorites, Ivuna and Orgueil, is -3.3, in the middle of the range. The δ11B values of the lunar rocks vary less than those of meteorites, from -6.0 to -3.9. The average δ11B of CI1 chondrites is -3.3, similar to that of terrestrial fresh mid-ocean ridge basalts (-6.5 to -1.2) and to the estimated mantle value of +0.2 (Ishikawa and Nakamura, 1992), which is the best representative of the whole Earth. The similarity of δ11B values in meteorites, lunar rocks, and those parts of the Earth unaffected by water implies that the boron isotopic composition of the Solar System is rather homogeneous. Recently, Chaussidon and Robert (1995) reported larger variation of δ11B values in chondrules of three chondrites, from -50 to +40. This degree of heterogeneity is absent from bulk meteorites.

DOI： 10.1016/S0016-7037(96)00338-9

Scopus

researchmap

Sm-Nd dating of garnet granulites from the Kohistan complex, northern Pakistan

Hiroshi Yamamoto, Eizo Nakamura

Journal of the Geological Society 153 ( 6 ) 965 - 969 1996年11月

記述言語：英語

Sm-Nd mineral-isochron ages of garnet granulites in the southern part of the Kohistan complex are determined. The 91.0±6.3 Ma age is obtained from a granulite body of the Jijal complex at Pattan and the 69.5±9.3 Ma age is obtained from a granulite body of the Chilas complex at Zambil. These ages indicate that the granulite bodies at Pattan and at Zambil had cooled to below upper amphibolite facies by about 90 Ma and about 70 Ma respectively. The time of cooling of the granulite of the Jijal complex is comparable to the time-lapse of the Asia-Kohistan collision (102-75 Ma), although that of the Chilas complex is probably younger than the Asia-Kohistan collision and certainly older than the Asia-India collision (c. 50 Ma).

DOI： 10.1144/gsjgs.153.6.0965

Scopus

researchmap

The arc lavas of the Shirahama Group, Japan: Sr and Nd isotopic data indicate mantle-derived bimodal magmatism

Y. Tamura, E. Nakamura

Journal of Petrology 37 ( 6 ) 1307 - 1319 1996年

記述言語：英語出版者・発行元：Oxford University Press

New Sr and Nd isotopic data are presented and integrated with previous data for the Shirahama Group Mio-Pliocene medium-K volcanic arc suite of south-central Honshu, Japan. Main results are: (1) The Shirahama lavas range in 87Sr/86Sr from 0·70315 to 0·70337 and in 143Nd/144Nd from 0·51298 to 0·51306
the Sr and Nd isotopic data cluster tightly within the mantle array, and all lie within an overlapping field of midocean ridge basalt and ocean island basalt
(2) small differences exist among the Shirahama tholeiitic series, calc-alkaline series and mixed lavas. The present isotopic data are consistent with a previously published model, which proposes that chemical variations in magmas of coexisting tholeiitic and calc-alkaline series are produced through crystal fractionation from mantle-derived magmas of basalt and magnesian andesite, respectively. Moreover, the tholeiitic series and the calc-alkaline series are isotopically identical. Thus, both magma series can be derived from a source mantle with the same isotopic composition, supporting the hypothesis of simultaneous generation of basalt and magnesian andesite magmas from a single diapir rising through the mantle wedge above the subduction zone. The differences of water content and temperature within the diapir are again thought to have been produced through dehydration and heating of an isotopically homogeneous hydrous diapir. The isotopic data show that the high-SiO2 lavas have the same isotopic compositions as more mafic lavas. These data and liquid lines of descent of the Shirahama magmas suggest that even rhyolites can be produced by differentiation from mantle-derived magmas without crustal contamination. Analyses from 38 other arc volcanoes have been compiled to investigate the intravolcano variability of 87Sr/86Sr. Twelve of these display no intravolcano strontium isotopic variability, as is the case with the Shirahama Group, but others show greater variation of 87Sr/86Sr from individual volcanic centers, presumably reflecting crustal contamination. Most of the latter volcanoes are underlain by thick continental crust. It is noteworthy, however, that the greater variations of 87Sr/86Sr correlate with SiO2 content
andesites or dacites, not basalts, from the same volcano have the lowest 87Sr/86Sr, and these rocks are calc-alkaline in terms of FeO*/MgO and SiO2. Theoretically, assimilation of continental crust by the isotopically uniform Shirahama magmas could produce these relationships. Given that mantle-derived basalt and magnesian andesite both encounter continental crust on their ascent to the surface, the hotter basalt magma would assimilate more crustal wallrocks than the cooler andesite, resulting in the basalt being more radiogenic. Fractional crystallization, magma mixing, and/or assimilation-fractional crystallization of these magmas in crustal magma chambers could produce large compositional variations, but the derivatives of the hotter basaltic magmas (tholeiitic series in the broad sense) would display greater contamination than those derived from the cooler andesitic magmas (calc-alkaline series).

DOI： 10.1093/petrology/37.6.1307

Scopus

researchmap

　前のページ - 次のページ　

<中村 栄三>

MISC - 中村 栄三

<中村　栄三>

MISC - 中村　栄三