2023/11/15 更新

写真a

サカグチ チエ
坂口 千恵
SAKAGUCHI Chie
所属
惑星物質研究所 助手
職名
助手
外部リンク

学位

  • 修士(理学) ( 茨城大学 )

 

論文

  • The Formation of a Rubble Pile Asteroid: Insights from the Asteroid Ryugu 査読

    Tsutomu Ota, Christian Potiszil, Katsura Kobayashi, Ryoji Tanaka, Hiroshi Kitagawa, Tak Kunihiro, Chie Sakaguchi, Masahiro Yamanaka, Eizo Nakamura

    Universe   2023年6月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.3390/universe9060293

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  • Organic Matter in the Asteroid Ryugu: What We Know So Far 招待 査読

    Christian Potiszil, Masahiro Yamanaka, Chie Sakaguchi, Tsutomu Ota, Hiroshi Kitagawa, Tak Kunihiro, Ryoji Tanaka, Katsura Kobayashi, Eizo Nakamura

    Life   2023年6月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.3390/life13071448

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  • Spectroscopic and Biophysical Methods to Determine Differential Salt‐Uptake by Primitive Membraneless Polyester Microdroplets

    Chen Chen, Ruiqin Yi, Motoko Igisu, Chie Sakaguchi, Rehana Afrin, Christian Potiszil, Tak Kunihiro, Katsura Kobayashi, Eizo Nakamura, Yuichiro Ueno, André Antunes, Anna Wang, Kuhan Chandru, Jihua Hao, Tony Z. Jia

    Small Methods   2023年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    Abstract

    α‐Hydroxy acids are prebiotic monomers that undergo dehydration synthesis to form polyester gels, which assemble into membraneless microdroplets upon aqueous rehydration. These microdroplets are proposed as protocells that can segregate and compartmentalize primitive molecules/reactions. Different primitive aqueous environments with a variety of salts could have hosted chemistries that formed polyester microdroplets. These salts could be essential cofactors of compartmentalized prebiotic reactions or even directly affect protocell structure. However, fully understanding polyester–salt interactions remains elusive, partially due to technical challenges of quantitative measurements in condensed phases. Here, spectroscopic and biophysical methods are applied to analyze salt uptake by polyester microdroplets. Inductively coupled plasma mass spectrometry is applied to measure the cation concentration within polyester microdroplets after addition of chloride salts. Combined with methods to determine the effects of salt uptake on droplet turbidity, size, surface potential and internal water distribution, it was observed that polyester microdroplets can selectively partition salt cations, leading to differential microdroplet coalescence due to ionic screening effects reducing electrostatic repulsion forces between microdroplets. Through applying existing techniques to novel analyses related to primitive compartment chemistry and biophysics, this study suggests that even minor differences in analyte uptake can lead to significant protocellular structural change.

    DOI: 10.1002/smtd.202300119

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  • Insights into the formation and evolution of extraterrestrial amino acids from the asteroid Ryugu

    Christian Potiszil, Tsutomu Ota, Masahiro Yamanaka, Chie Sakaguchi, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Hiroshi Kitagawa, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Eizo Nakamura

    Nature Communications   14 ( 1 )   2023年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    Abstract

    All life on Earth contains amino acids and carbonaceous chondrite meteorites have been suggested as their source at the origin of life on Earth. While many meteoritic amino acids are considered indigenous, deciphering the extent of terrestrial contamination remains an issue. The Ryugu asteroid fragments (JAXA Hayabusa2 mission), represent the most uncontaminated primitive extraterrestrial material available. Here, the concentrations of amino acids from two particles from different touchdown sites (TD1 and TD2) are reported. The concentrations show that N,N-dimethylglycine (DMG) is the most abundant amino acid in the TD1 particle, but below detection limit in the other. The TD1 particle mineral components indicate it experienced more aqueous alteration. Furthermore, the relationships between the amino acids and the geochemistry suggest that DMG formed on the Ryugu progenitor body during aqueous alteration. The findings highlight the importance of aqueous chemistry for defining the ultimate concentrations of amino acids in primitive extraterrestrial samples.

    DOI: 10.1038/s41467-023-37107-6

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    その他リンク: https://www.nature.com/articles/s41467-023-37107-6

  • On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

    Eizo NAKAMURA, Katsura KOBAYASHI, Ryoji TANAKA, Tak KUNIHIRO, Hiroshi KITAGAWA, Christian POTISZIL, Tsutomu OTA, Chie SAKAGUCHI, Masahiro YAMANAKA, Dilan M. RATNAYAKE, Havishk TRIPATHI, Rahul KUMAR, Maya-Liliana AVRAMESCU, Hidehisa TSUCHIDA, Yusuke YACHI, Hitoshi MIURA, Masanao ABE, Ryota FUKAI, Shizuho FURUYA, Kentaro HATAKEDA, Tasuku HAYASHI, Yuya HITOMI, Kazuya KUMAGAI, Akiko MIYAZAKI, Aiko NAKATO, Masahiro NISHIMURA, Tatsuaki OKADA, Hiromichi SOEJIMA, Seiji SUGITA, Ayako SUZUKI, Tomohiro USUI, Toru YADA, Daiki YAMAMOTO, Kasumi YOGATA, Miwa YOSHITAKE, Masahiko ARAKAWA, Atsushi FUJII, Masahiko HAYAKAWA, Naoyuki HIRATA, Naru HIRATA, Rie HONDA, Chikatoshi HONDA, Satoshi HOSODA, Yu-ichi IIJIMA, Hitoshi IKEDA, Masateru ISHIGURO, Yoshiaki ISHIHARA, Takahiro IWATA, Kosuke KAWAHARA, Shota KIKUCHI, Kohei KITAZATO, Koji MATSUMOTO, Moe MATSUOKA, Tatsuhiro MICHIKAMI, Yuya MIMASU, Akira MIURA, Tomokatsu MOROTA, Satoru NAKAZAWA, Noriyuki NAMIKI, Hirotomo NODA, Rina NOGUCHI, Naoko OGAWA, Kazunori OGAWA, Chisato OKAMOTO, Go ONO, Masanobu OZAKI, Takanao SAIKI, Naoya SAKATANI, Hirotaka SAWADA, Hiroki SENSHU, Yuri SHIMAKI, Kei SHIRAI, Yuto TAKEI, Hiroshi TAKEUCHI, Satoshi TANAKA, Eri TATSUMI, Fuyuto TERUI, Ryudo TSUKIZAKI, Koji WADA, Manabu YAMADA, Tetsuya YAMADA, Yukio YAMAMOTO, Hajime YANO, Yasuhiro YOKOTA, Keisuke YOSHIHARA, Makoto YOSHIKAWA, Kent YOSHIKAWA, Masaki FUJIMOTO, Sei-ichiro WATANABE, Yuichi TSUDA

    Proceedings of the Japan Academy, Series B   98 ( 6 )   227 - 282   2022年6月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japan Academy  

    DOI: 10.2183/pjab.98.015

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  • Geochronology, Petrogenesis and Oxidation State of the Northparkes Igneous Suite, New South Wales, Australia: Implications for Magma Fertility

    Hongda Hao, Ian H. Campbell, David R. Cooke, Eizo Nakamura, Chie Sakaguchi

    ECONOMIC GEOLOGY   116 ( 5 )   1161 - 1187   2021年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SOC ECONOMIC GEOLOGISTS, INC  

    New geochronological and geochemical data for the barren and ore-associated suites from the Northparkes porphyry Cu-Au deposits, Australia, have implications for magma fertility. The Goonumbla and Wombin Volcanics and intrusions are barren in the Northparkes area. A sample from Wombin suite yielded a zircon U-Pb age of 433.8 +/- 3.1 Ma, whereas the ore-associated porphyries yielded ages between 441.8 +/- 3.7 and 436.3 +/- 4.5 Ma. The bulk of the mineralization at Northparkes is associated with a K-feldspar-phyric quartz monzonite porphyry (K-QMP), which gave U-Pb zircon ages of 441.8 +/- 3.7 and 441.1 +/- 2.5 Ma. Whole-rock Sr-Nd isotope compositions of the Goonumbla, Wombin, and ore-associated suites are similar, with (Sr-87/Sr-86) i = 0.704112 to 0.704424 and epsilon(Nd) = 5.6 to 6.9, which is typical of primitive intraoceanic island arcs, and their Pb isotope values lie within the MORB array. Most of the zircons from the Wombin and ore-associated suites have arc mantlelike O-Hf isotope compositions, with delta O-18 values that vary from 6.13 to 4.95, and epsilon(Hf)(t) from 11.5 to 6. These results suggest that the Goonumbla, Wombin, and ore-associated suites originated from typical arc mantle. The magmas that produced the Goonumbla and Wombin suites were dominated by plagioclase-pyroxene fractionation, and the Wombin suite has a low oxidation state with.FMQ between similar to 0 and 1.5. They were relatively reduced and dry. This combination resulted in early sulfide saturation, probably without reaching fluid saturation. Trace element modeling shows that plagioclase-amphibole dominated the later stages of fractionation of the ore-associated suite, implying that it had a higher water content than the barren suites. It was also more oxidized (Delta FMQ from similar to 0 to 4). The result was late sulfide saturation, which was followed shortly thereafter by voluminous fluid release. As a consequence, the ore-forming fluid effectively transferred Cu and Au from the magma to the site of hydrothermal ore deposition. We suggest that the higher water content and oxidation state of the ore-associated suite was due to the deep underlying magma chamber, which was recharged by many more pulses of magma than the chamber that underlay the barren suites. This is more effective in raising the concentration of incompatible water and ferric iron in the residual melt than straight fractional crystallization. High oxygen fugacities and water contents played a significant role in determining the timing of sulfide and fluid saturation, respectively, and as a result, they had a critical influence on magma fertility.

    DOI: 10.5382/econgeo.4825

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  • Boron Isotope Fractionation between Liquid and Gas at Saturated Water Vapor Line

    A. Yu Bychkov, I. Yu Nikolaeva, Y. V. Bychkova, Ch Sakaguchi, E. Nakamura

    Geochemistry International   58 ( 11 )   1257 - 1261   2020年11月

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    掲載種別:研究論文(学術雑誌)  

    Abstract: The first experimental data were obtained on the distribution of boron isotopes between gas and liquid at 100–350°С and the pressure of saturated water vapor, and the effect of pH on this distribution at 100°С was studied. The results showed that the value of δ11Bgas–δ11Bliquid was 5.9, 3.7, 1.1, 0.8, and –1.3 ‰ at 100, 200, 250, 300, and 350°С. In an alkaline solution, the boron distribution coefficient between gas and liquid decreases, and the isotopic shift increases; at 100°C and pH 9.1 it is 17.0. The isotopic composition of the boron of thermal waters of the Mutnovsky geothermal system (Kamchatka Peninsula, Russia) was investigated. In thermal springs, a large spread of δ11B values from 2.8 to 18‰ was determined. A wide range of isotopic compositions can be explained by the fractionation of boron between gas and liquid.

    DOI: 10.1134/S001670292011004X

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  • Various Ages of Recycled Material in the Source of Cenozoic Basalts in SE China: Implications for the Role of the Hainan Plume

    Yan-Qing Li, Hiroshi Kitagawa, Eizo Nakamura, Changqian Ma, Xiangyun Hu, Katsura Kobayashi, Chie Sakaguchi

    JOURNAL OF PETROLOGY   61 ( 6 )   2020年6月

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    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  

    Subduction processes introduce crustal materials into the mantle, and mantle plumes return them to the surface. However, when and how the subducted materials were recorded in the plume-related basalts remains unclear. Here we investigate geochronology, bulk-rock composition, and Sr-Nd-Pb isotopes of Cenozoic basalts from Southeast China, occurring near the west Pacific subduction zone and the seismically detected Hainan plume. Volcanism beginning in the late Oligocene in the continental margin of SE China consistently becomes younger landward. Together with a compilation of published results on the synchronous basalts from the South China Sea seamounts and the Indochina peninsula, the volcanoes close to the Pacific subduction zone exhibit more radiogenic Pb and Sr isotopes associated with less radiogenic Nd isotopes compared with those of the inland volcanoes. Such spatiotemporal variations in radiogenic isotopes imply oceanic crusts of different ages in the source, each corresponding to a different geographical volcanic belt. Major-element features such as low CaO, high TiO2 and high Fe/Mn ratios imply that pyroxenite/eclogite could serve as a source lithology of the SE China basalts. Specific trace-element signatures reveal the important roles of recycled oceanic crust along with surface sediment, which was inconsistently dehydrated during subduction. A geologically, geochemically, and geophysically plausible scenario is proposed to illustrate the time-space-source correlation of the late Cenozoic basaltic lavas in SE Asia. The Hainan plume delivered the ancient subducted crust (1.5 Ga) from the core-mantle boundary and, subsequently, the subducted Pacific plate crustal materials from the mantle transition zone to the shallow mantle as a result of mantle convection induced by continuous subduction of the Pacific plate. Such recycled materials of different ages contributed to the geographical compositional heterogeneities of the late Cenozoic basaltic lavas in SE Asia.

    DOI: 10.1093/petrology/egaa060

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  • A Method to Suppress Isobaric and Polyatomic Interferences for Measurements of Highly Siderophile Elements in Desilicified Geological Samples

    Xiaoyu Zhou, Ryoji Tanaka, Masahiro Yamanaka, Chie Sakaguchi, Eizo Nakamura

    GEOSTANDARDS AND GEOANALYTICAL RESEARCH   43 ( 4 )   611 - 633   2019年12月

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    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  

    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.

    DOI: 10.1111/ggr.12280

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  • Boron Isotopes in the Puga Geothermal System, India, and Their Implications for the Habitat of Early Life 国際誌

    Luke H. Steller, Eizo Nakamura, Tsutomu Ota, Chie Sakaguchi, Mukund Sharma, Martin J. Van Kranendonk

    ASTROBIOLOGY   19 ( 12 )   1459 - 1473   2019年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MARY ANN LIEBERT, INC  

    Boron is associated with several Archean stromatolite deposits, including the tourmaline-rich Barberton stromatolites in South Africa and tourmaline-bearing pyritic laminae associated with stromatolites of the 3.48 Ga Dresser Formation in the Pilbara Craton, Australia. Boron is also a critical element in prebiotic organic chemistry, including in the formation of ribose, a crucial component in RNA. As geological evidence and advances in prebiotic chemistry are now suggesting that hot spring activity may be associated with the origins of life, an understanding of boron and its mobility and isotopic fractionation in geothermal settings may provide important insights into the setting for the origin of life. Here, we report on the boron isotopic compositions and elemental concentrations in a range of fluid, sediment, and mineral samples from the active, boron-rich Puga geothermal system in the Himalayas, India. This includes one of the lowest boron isotope values ever recorded in modern settings: diatom-rich sediments (delta B-11 = -41.0 parts per thousand) in a multiphase fractionation system where evaporation is not the dominant form of isotope fractionation. Instead, the extreme boron isotopic fractionation is ascribed to the incorporation of tetrahedral B-10 borate anions in precipitating amorphous silica. These findings expand the known limits and drivers of boron isotope fractionation, as well as provide insight into the concentration and fractionation of boron in Archean hot spring environments.

    DOI: 10.1089/ast.2018.1966

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  • Hypervelocity collision and water-rock interaction in space preserved in the Chelyabinsk ordinary chondrite

    Eizo Nakamura, Tak Kunihiro, Tsutomu Ota, Chie Sakaguchi, Ryoji Tanaka, Hiroshi Kitagawa, Katsura Kobayashi, Masahiro Yamanaka, Yuri Shimaki, Gray E. Bebout, Hitoshi Miura, Tetsuo Yamamoto, Vladimir Malkovets, Victor Grokhovsky, Olga Koroleva, Konstantin Litasov

    PROCEEDINGS OF THE JAPAN ACADEMY SERIES B-PHYSICAL AND BIOLOGICAL SCIENCES   95 ( 4 )   165 - 177   2019年4月

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    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  

    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.

    DOI: 10.2183/pjab.95.013

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  • Determination of Abundances of Fifty-Two Elements in Natural Waters by ICP-MS with Freeze-Drying Pre-concentration

    Que D. Hoang, Tak Kunihiro, Chie Sakaguchi, Masahiro Yamanaka, Hiroshi Kitagawa, Eizo Nakamura

    GEOSTANDARDS AND GEOANALYTICAL RESEARCH   43 ( 1 )   147 - 161   2019年3月

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    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  

    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.

    DOI: 10.1111/ggr.12245

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  • Platinum-Group Element Geochemistry of the Escondida Igneous Suites, Northern Chile: Implications for Ore Formation

    Hongda Hao, Ian H. Campbell, Jeremy P. Richards, Eizo Nakamura, Chie Sakaguchi

    JOURNAL OF PETROLOGY   60 ( 3 )   487 - 514   2019年3月

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    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  

    Platinum-group element (PGE) geochemistry may be used to constrain the timing of sulfide saturation in magmas, which influences the Cu and Au fertility of evolving magmatic systems. We report new geochronological and geochemical data, with emphasis on PGE geochemistry, for a suite of regional porphyritic hornblende-diorite intrusions and ore-bearing porphyries from the super-giant Escondida and smaller Zaldivar Cu deposits of Northern Chile. The regional dioritic intrusions have zircon U-Pb ages between 396 to 371Ma, which overlap with the ages of the ore-bearing Escondida and Zaldivar porphyries (381 to 350Ma). Whole-rock major and trace element, and Sr-Nd-Pb and zircon O-Hf isotope geochemistry indicate that the regional diorites and ore-bearing porphyries are co-magmatic and originated from the same mantle-derived magma by fractional crystallization, with minor contamination by Paleozoic crust (approximate to 10%). The low concentrations of PGE in the regional diorites show that they reached sulfide saturation before the MgO content of the melt fell to 47wt %, the MgO content of the most primitive sample analysed. The fraction of sulfide melt which separated from the melts that formed the regional diorites is estimated to be approximate to 012wt %; this resulted in the partitioning of highly chalcophile elements (Au and PGE) into a sulfide phase that was retained in cumulus rocks at depth. However, the fraction of sulfide melt was too low to have a significant effect on the Cu content of the fractionating melt. As a consequence, when the evolving melt eventually reached volatile saturation, it contained enough Cu (40 +/- 10ppm) to form a super-giant Cu deposit. In contrast, Au was largely stripped from the melt by sulfide precipitation, with the result that the mineralization at Escondida is Cu dominant, with only minor Au. The Zaldivar deposit, on the other hand, contains even less Au, which is attributed to a longer fractionation interval between sulfide and volatile saturation. This study provides evidence to support previously proposed models which suggest that the timing of sulfide saturation, the amount of sulfide melt produced, the water content and oxidation state of the melt, and the magma volume are critical factors in determining the potential to form a porphyry Cu deposit. Plots of Pd/MgO against Y can be used as empirical indicators of magma fertility for porphyry mineralization, and to discriminate between Cu-Au and Cu-dominated systems, but cannot predict the size of the deposit. The super-giant status of the Escondida deposit is attributed to it being underlain by a large batholith with a calculated minimum mass of 10(12) tonnes (approximate to 400km(3)).

    DOI: 10.1093/petrology/egz004

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  • Petrology, Trace Element and Sr, Nd, Hf Isotope Geochemistry of the North Lanzo Peridotite Massif (Western Alps, Italy)

    Luisa Guarnieri, Eizo Nakamura, Giovanni B. Piccardo, Chie Sakaguchi, Nobumichi Shimizu, Riccardo Vannucci, Alberto Zanetti

    JOURNAL OF PETROLOGY   53 ( 11 )   2259 - 2306   2012年11月

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    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  

    Field, petrographic-structural and geochemical data are reported for spinel and plagioclase peridotites from the northern domain of the Lanzo peridotite massif (Western Alps). The North Lanzo peridotites are extremely heterogeneous in terms of mineral mode, texture and chemistry. They can be referred to four major groups: (1) spinel harzburgites with coarse granular to porphyroclastic structures; (2) pyroxene-depleted spinel harzburgites recording olivine-forming or pyroxene-consuming microtextures; (3) spinel lherzolites with porphyroclastic to foliated and banded structures; (4) plagioclase-enriched spinel lherzolites. Major and trace element characterization of whole-rocks and their constituent minerals allows reconstruction of the complex series of pre- to syn-rift events this mantle sector underwent. Sr, Nd and Hf isotope data provide information on the nature of infiltrating melts and time constraints. More depleted harzburgites represent refractory protoliths that after melt extraction, possibly in the presence of residual garnet, underwent a first episode of refertilization by enriched mid-ocean ridge basalt (E-MORB)-like melts, whereas harzburgites and spinel lherzolites with ocean island basalt (OIB) signatures document the successive migration of alkaline melts. The most noticeable feature of this group of rocks is their Nd-Hf decoupling, specifically the very high Hf-176/Hf-177 coupled with very low Nd-143/Nd-144. Lu-Hf data for these peridotites define an similar to 260 Ma errorchron that is interpreted as evidence of mixing during relatively recent times between old (most probably Proterozoic) refractory subcontinental mantle and OIB-type melts. This event most probably occurred during extension (Triassic times) or during the onset of exhumation (Liassic times). Plagioclase peridotites document the last refertilization episode, involving the shallow-level impregnation of harzburgite mantle by evolved MORB melts before its sea-floor emplacement. This Middle Jurassic event caused the almost complete resetting of the original trace element and Sr-87/Sr-86 composition. The combination of structural, petrological and geochemical information for a north-south Lanzo traverse, from the North Massif to the South Massif, notwithstanding the effects of the alpine orogeny, allows the study of the complete evolution of a sector of old (Proterozoic?) mantle since the early stages of melt removal and allows reconstruction of the tectonic and magmatic events during continental extension leading to the opening of the Jurassic Ligurian-Piedmontese basin. North Lanzo fundamentally preserves the record of pre-syn-rift ancient episodes, whereas South Lanzo better highlights the processes that deeply modified and refertilized the older lithosphere during subsequent lithosphere extension. Slow to very slow extension led to sea-floor exposure of the subcontinental lithospheric mantle (North Lanzo) at a marginal position, close to the Adria continental margin, and of the deeply melt-modified lithospheric mantle (Lanzo South) in a more distal setting of the basin. In this respect, the Lanzo traverse is closely similar to the ocean-continent transition in slow- or ultraslow-spreading oceanic basins, such as the North Atlantic.

    DOI: 10.1093/petrology/egs049

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  • Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft 国際誌

    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

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    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

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  • Timescales of magma differentiation from basalt to andesite beneath Hekla Volcano, Iceland: Constraints from U-series disequilibria in lavas from the last quarter-millennium flows

    Takele A. Chekol, Katsura Kobayashi, Tetsuya Yokoyama, Chie Sakaguchi, Eizo Nakamura

    GEOCHIMICA ET COSMOCHIMICA ACTA   75 ( 1 )   256 - 283   2011年1月

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

    Measurements of U-238-Th-230-Ra-226 disequilibria, Sr-Nd-Pb-Hf isotopes and major-trace elements have been conducted for lavas erupted in the last quarter-millennium at Hekla volcano, Iceland. The volcanic rocks range from basalt to dacite. Most of the lavas (excluding dacitic samples) display limited compositional variations in radiogenic Sr-Nd-Pb-Hf isotopes (Sr-87/Sr-86 = 0.70319-0.70322; Nd-143/Nd-144 = 0.51302-0.51305; Ph-206/Pb-204 = 19.04-19.06; Pb-207/Pb-204 = 15.53-15.54; Pb-208/Pb-204 = 38.61-38.65; Hf-176/Hf-177 = 0.28311-0.28312). All the samples possess (Th-230/U-238) disequilibrium with Th-230 excesses, and they show systematic variations in (Th-230/Th-232) and (U-238/Th-232) ratios. The highest Ra-226 excesses occur in the basalt and most differentiated andesite lavas, while some basaltic-andesite lavas have (Ra-226/Th-230) ratio that are close to equilibrium. The U-238-Th-230-Ra-226 disequilibria variations cannot be produced by simple closed-system fractional crystallization with radioactive decay of Th-230 and Ra-226 in a magma chamber. A closed-system fractional crystallization model and assimilation and fractional crystallization (AFC) model indicate that the least differentiated basaltic andesites were derived from basalt by fractional crystallization with a differentiation age of similar to 24 +/- 11 kyr, whereas the andesites were formed by assimilation of crustal material and fractionation of the basaltic-andesites within 2 kyr. Apatite is inferred to play a key role in fractionating the parent daughter nuclides in Th-230-U-238 and Ra-226-Th-230 to make the observed variations. Our proposed model is that several batches of basaltic-andesite magmas that formed by fractional crystallization of a basaltic melt from a deeper reservoir, were periodically injected into the shallow crust to form individual magma pockets, and subsequently modifying the original magma compositions via simultaneous assimilation and fractional crystallization. The assimilant is the dacitic melt, which formed by partial melting of the crust. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.gca.2010.10.001

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  • An assessment of upper mantle heterogeneity based on abyssal peridotite isotopic compositions

    J. M. Warren, N. Shimizu, C. Sakaguchi, H. J.B. Dick, E. Nakamura

    Journal of Geophysical Research: Solid Earth   114 ( 12 )   2009年

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    掲載種別:研究論文(学術雑誌)  

    Abyssal peridotites, the depleted solid residues of ocean ridge melting, are the most direct samples available to assess upper oceanic mantle composition. We present detailed isotope and trace element analyses of pyroxene mineral separates from Southwest Indian Ridge abyssal peridotites and pyroxenites in order to constrain the size and length scale of mantle heterogeneity. Our results demonstrate that the mantle can be highly heterogeneous to <1 km and even <0.1 m length scales. Examination of Nd isotopes in relation to modal, trace, and major element compositions indicate that the length scales and amplitudes of heterogeneities in abyssal peridotites reflect both ancient mantle heterogeneity and recent modification by melting, melt-rock reaction and melt crystallization. The isotopic and trace element compositions of pyroxenite veins in this study indicate that they are not direct remnants of recycled oceanic crust, but instead are formed by recent melt crystallization. Combined with existing data sets, the results show that the average global isotopic composition of peridotites is similar to that of mid-ocean ridge basalts, though peridotites extend to significantly more depleted 143Nd/144Nd and 87Sr/86Sr. Standard isotope evolution models of upper mantle composition do not predict the full isotopic range observed among abyssal peridotites, as they do not account adequately for the complexities of ancient and recent melting processes. Copyright 2009 by the American Geophysical Union.

    DOI: 10.1029/2008JB006186

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  • Evolution of an isotopically depleted mantle xenolith from salt lake crater, Hawaii 査読

    E Nakamura, C Sakaguchi, R Tanaka, T Moriguti, Kushiro, I

    GEOCHIMICA ET COSMOCHIMICA ACTA   67 ( 18 )   A324 - A324   2003年9月

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    記述言語:英語   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

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  • Comprehensive geochemical analyses of small amounts (< 100 mg) of extraterrestrial samples for the analytical competition related to the sample return mission MUSES-C

    中村 栄三, 牧嶋 昭夫, 森口 拓弥, 小林 桂, 坂口 千恵, 横山 哲也, 田中 亮史, 栗谷 豪, 竹井 宏行, Nakamura Eizo, Makishima Akio, Moriguti Takuya, Kobayashi Katsura, Sakaguchi Chie, Yokoyama Tetsuya, Tanaka Ryoji, Kuritani Takeshi, Takei Hiroyuki

    The Institute of Space and Astronautical Science report. S.P. : The First Open Competition for the MUSES-C Asteroidal Sample Preliminary Examination Team   ( 16 )   49 - 101   2003年3月

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    記述言語:英語   出版者・発行元:宇宙科学研究所  

    資料番号: SA0200006000

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MISC

  • 地球惑星物質総合解析システムの構築と応用

    中村栄三, 牧嶋昭夫, 森口拓弥, 小林桂, 田中亮吏, 国広卓也, 北川宙, 太田努, 坂口千恵, 山中正博

    法政大学イオンビーム工学研究所シンポジウム講演予稿集   36th   2017年

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  • Geochemistry of volcanic and plutonic rocks from the southern Musoma-Mara greenstone belt: Implication for the evolution of the Tanzania craton

    C. W. Messo, K. Yamashita, K. Kobayashi, A. Makishima, C. Sakaguchi, E. Nakamura

    GEOCHIMICA ET COSMOCHIMICA ACTA   72 ( 12 )   A622 - A622   2008年7月

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    記述言語:英語   掲載種別:研究発表ペーパー・要旨(国際会議)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

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  • 同位体希釈法と内標準法を併用した、ICP質量分析法によるLi, Be, Rb, Sr, Y, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Pb, Th, Uの同時測定法の開発

    牧嶋 昭夫, 北川 宙, 坂口 千恵, 中村 栄三

    日本鉱物学会・学術講演会,日本岩石鉱物鉱床学会学術講演会講演要旨集   2004   237 - 237   2004年9月

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    記述言語:英語   出版者・発行元:日本鉱物科学会  

    同位体希釈法と内標準法を併用した、ICP質量分析法によるLi, Be, Rb, Sr, Y, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Pb, Th, Uの同時測定法の開発をおこなった。

    DOI: 10.14824/jampeg.2004.0.64.0

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  • ハワイアンプリューム端成分としてのマントル捕獲岩の発見?

    中村 栄三, 坂口 千恵, 田中 亮吏, 森口 拓弥, 久城 育夫

    日本岩石鉱物鉱床学会 学術講演会 講演要旨集   2002   251 - 251   2002年

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    出版者・発行元:日本鉱物科学会  

    DOI: 10.14824/jampeg.2002.0.251.0

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