start-ver=1.4
cd-journal=joma
no-vol=2007
cd-vols=
no-issue=10
article-no=
start-page=22
end-page=23
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2007
dt-pub=200710
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=21世紀 岡山の100人 岡山大学地球物質科学研究センター センター長 中村栄三
en-subtitle=
kn-subtitle=
en-abstract=月刊プラザ岡山 10月号(2007) ; copyright (c) 2007（株）オークシード
kn-abstract=岡山大学地球物質科学研究センターは鳥取県三朝町に整然と佇んでいるが、中身は驚くほど熱い。研究成果を惜しみなく発信し、地球科学に関する先導的役割を担う。研究センターの分析能力は「世界中の他の研究室の追随を許さない」と国際評価され、その鋭い眼力は自らの研究のみならず日本の教育問題をも見据える。
en-copyright=
kn-copyright=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=中村栄三
kn-aut-sei=中村
kn-aut-mei=栄三
aut-affil-num=1
ORCID=
affil-num=1
en-affil=
kn-affil=岡山大学
en-keyword=岡山大学
kn-keyword=岡山大学
en-keyword=地球物質科学研究センター
kn-keyword=地球物質科学研究センター
END
start-ver=1.4
cd-journal=joma
no-vol=43
cd-vols=
no-issue=1
article-no=
start-page=147
end-page=161
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2018
dt-pub=20181025
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Determination of Abundances of Fifty-Two Elements in Natural Waters by ICP-MS with Freeze-Drying Pre-concentration
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= To precisely determine the abundances of fifty-two elements found within natural water samples, with mass fractions down to fg g(-1) level, we have developed a method which combines freeze-drying pre-concentration (FDC) and isotope dilution internal standardisation (ID-IS). By sublimation of H2O, the sample solution was reduced to < 1/50 of the original volume. To determine element abundance with accuracy better than 10%, we found that for solutions being analysed by mass spectrometry the HNO3 concentration should be > 0.3 mol l(-1) to avoid hydrolysis. Matrix-affected signal suppression was not significant for the solutions with NaCl concentrations lower than 0.2 and 0.1 cg g(-1) for quadrupole ICP-MS and sector field ICP-MS, respectively. The recovery yields of elements after FDC were 97-105%. The detection limits for the sample solutions prepared by FDC were <= 10 pg g(-1), except for Na, K and Ca. Blanks prepared using FDC were at pg-levels, except for eleven elements (Na, Mg, Al, P, Ca, Mn, Fe, Co, Ni, Cu and Zn). The abundances of fifty-two elements in bottled drinking water were determined from five different geological sources with mass fractions ranging from the fg g(-1) to mu g g(-1) level with high accuracy.
en-copyright=
kn-copyright=
en-aut-name=HoangQue D.
en-aut-sei=Hoang
en-aut-mei=Que D.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=KunihiroTak
en-aut-sei=Kunihiro
en-aut-mei=Tak
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=SakaguchiChie
en-aut-sei=Sakaguchi
en-aut-mei=Chie
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=YamanakaMasahiro
en-aut-sei=Yamanaka
en-aut-mei=Masahiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=KitagawaHiroshi
en-aut-sei=Kitagawa
en-aut-mei=Hiroshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=
affil-num=1
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=3
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=4
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=5
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=6
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=pre-concentration
kn-keyword=pre-concentration
en-keyword=freeze-drying
kn-keyword=freeze-drying
en-keyword=ID-IS
kn-keyword=ID-IS
en-keyword=natural water
kn-keyword=natural water
en-keyword=drinking water
kn-keyword=drinking water
END
start-ver=1.4
cd-journal=joma
no-vol=95
cd-vols=
no-issue=4
article-no=
start-page=165
end-page=177
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=20190411
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Hypervelocity collision and water-rock interaction in space preserved in the Chelyabinsk ordinary chondrite
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=A comprehensive geochemical study of the Chelyabinsk meteorite reveals further details regarding its history of impact-related fragmentation and melting, and later aqueous alteration, during its transit toward Earth. We support an similar to 30 Ma age obtained by Ar-Ar method (Beard et al., 2014) for the impact-related melting, based on Rb-Sr isotope analyses of a melt domain. An irregularly shaped olivine with a distinct 0 isotope composition in a melt domain appears to be a fragment of a silicate-rich impactor. Hydrogen and Li concentrations and isotopic compositions, textures of Fe oxyhydroxides, and the presence of organic materials located in fractures, are together consistent with aqueous alteration, and this alteration could have pre-dated interaction with the Earth's atmosphere. As one model, we suggest that hypervelocity capture of the impact-related debris by a comet nucleus could have led to shock-wave-induced supercritical aqueous fluids dissolving the silicate, metallic, and organic matter, with later ice sublimation yielding a rocky rubble pile sampled by the meteorite.
en-copyright=
kn-copyright=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=KunihiroTak
en-aut-sei=Kunihiro
en-aut-mei=Tak
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=OtaTsutomu
en-aut-sei=Ota
en-aut-mei=Tsutomu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=SakaguchiChie
en-aut-sei=Sakaguchi
en-aut-mei=Chie
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=TanakaRyoji
en-aut-sei=Tanaka
en-aut-mei=Ryoji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
en-aut-name=KitagawaHiroshi
en-aut-sei=Kitagawa
en-aut-mei=Hiroshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=
en-aut-name=KobayashiKatsura
en-aut-sei=Kobayashi
en-aut-mei=Katsura
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=
en-aut-name=YamanakaMasahiro
en-aut-sei=Yamanaka
en-aut-mei=Masahiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=
en-aut-name=ShimakiYuri
en-aut-sei=Shimaki
en-aut-mei=Yuri
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=9
ORCID=
en-aut-name=BeboutGray E.
en-aut-sei=Bebout
en-aut-mei=Gray E.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=10
ORCID=
en-aut-name=MiuraHitoshi
en-aut-sei=Miura
en-aut-mei=Hitoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=11
ORCID=
en-aut-name=YamamotoTetsuo
en-aut-sei=Yamamoto
en-aut-mei=Tetsuo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=12
ORCID=
en-aut-name=MalkovetsVladimir
en-aut-sei=Malkovets
en-aut-mei=Vladimir
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=13
ORCID=
en-aut-name=GrokhovskyVictor
en-aut-sei=Grokhovsky
en-aut-mei=Victor
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=14
ORCID=
en-aut-name=KorolevaOlga
en-aut-sei=Koroleva
en-aut-mei=Olga
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=15
ORCID=
en-aut-name=LitasovKonstantin
en-aut-sei=Litasov
en-aut-mei=Konstantin
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=16
ORCID=
affil-num=1
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=3
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=4
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=5
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=6
en-affil=Okayama Univ, Inst Planetary Mat, Pheast Mem Lab Geochem & Cosmochem
kn-affil=
affil-num=7
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=8
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=9
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=10
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=11
en-affil=Graduate School of Natural Sciences, Nagoya City University
kn-affil=
affil-num=12
en-affil=Institute of Low Temperature Science, Hokkaido University
kn-affil=
affil-num=13
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=14
en-affil=Institute of Physics and Technology, Ural Federal University
kn-affil=
affil-num=15
en-affil=Institute of Mineralogy, Ural Branch of the Russian Academy of Sciences South-Ural State University
kn-affil=
affil-num=16
en-affil=V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences
kn-affil=
en-keyword=ordinary chondrite
kn-keyword=ordinary chondrite
en-keyword=chronology
kn-keyword=chronology
en-keyword=geochemistry
kn-keyword=geochemistry
en-keyword=impact melting
kn-keyword=impact melting
en-keyword=asteroid
kn-keyword=asteroid
en-keyword=comet
kn-keyword=comet
END
start-ver=1.4
cd-journal=joma
no-vol=252
cd-vols=
no-issue=
article-no=
start-page=107
end-page=125
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=20190501
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Lithium- and oxygen-isotope compositions of chondrule constituents in the Allende meteorite
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= We report in situ ion-microprobe analyses of Li- and O-isotope compositions for olivine, low-Ca pyroxene, high-Ca pyroxene, and chondrule mesostasis/plagioclase in nine chondrules from the Allende CV3 chondrite. Based on their mineralogy and O-isotope compositions, we infer that the chondrule mesostasis/plagioclase and ferroan olivine rims were extensively modified or formed during metasomatic alteration and metamorphism on the Allende parent asteroid. We excluded these minerals in order to determine the correlations between Li and both O and the chemical compositions of olivines and low-Ca pyroxenes in the chondrules and their igneous rims. Based on the O-isotope composition of the olivines, nine chondrules were divided into three groups. Average Δ17O of olivines (Fo>65) in group 1 and 2 chondrules are ?5.3?±?0.4 and ?6.2?±?0.4‰, respectively. Group 3 chondrules are characterized by the presence of 16O-rich relict grains and the Δ17O of their olivines range from ?23.7 to ?6.2‰. In group 1 olivines, as Fa content increases, variation of δ7Li becomes smaller and δ7Li approaches the whole-rock value (2.4‰; Seitz et al., 2012), suggesting nearly complete Li-isotope equilibration. In group 2 and 3 olivines, variation of δ7Li is limited even with a significant range of Fa content. We conclude that Li-isotope compositions of olivine in group 1 chondrules were modified not by an asteroidal process but by an igneous-rim formation process, thus chondrule olivines retained Li-isotope compositions acquired in the protosolar nebula. In olivines of the group 3 chondrule PO-8, we observed a correlation between O and Li isotopes: In relict 16O-rich olivine grains with Δ17O of ??25 to ?20‰, δ7Li ranges from ?23 to ?3‰; in olivine grains with Δ17O?>??20‰, δ7Li is nearly constant (?8?±?4‰). Based on the Li-isotope composition of low-Ca pyroxenes, which formed from melt during the crystallization of host chondrules and igneous rims, the existence of a gaseous reservoir with a δ7Li????11‰ is inferred.
en-copyright=
kn-copyright=
en-aut-name=KunihiroTakuya
en-aut-sei=Kunihiro
en-aut-mei=Takuya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=OtaTsutomu
en-aut-sei=Ota
en-aut-mei=Tsutomu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
affil-num=1
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=3
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=Lithium
kn-keyword=Lithium
en-keyword=Oxygen
kn-keyword=Oxygen
en-keyword=Chondrule
kn-keyword=Chondrule
en-keyword=Chondrite
kn-keyword=Chondrite
en-keyword=Asteroid
kn-keyword=Asteroid
en-keyword=Allende
kn-keyword=Allende
en-keyword=Igneous rim
kn-keyword=Igneous rim
en-keyword=SIMS
kn-keyword=SIMS
END
start-ver=1.4
cd-journal=joma
no-vol=43
cd-vols=
no-issue=4
article-no=
start-page=611
end-page=633
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=20190320
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Method to Suppress Isobaric and Polyatomic Interferences for Measurements of Highly Siderophile Elements in Desilicified Geological Samples
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= Sample decomposition using inverse aqua regia at elevated temperatures and pressures (e.g., Carius tube or high‐pressure asher) is the most common method used to extract highly siderophile elements (HSEs: Ru, Rh, Pd, Re, Os, Ir, Pt and Au) from geological samples. Recently, it has been recognised that additional HF desilicification is necessary to better recover HSEs, potentially contained within silicate or oxide minerals in mafic samples, which cannot be dissolved solely by inverse aqua regia. However, the abundance of interfering elements tends to increase in the eluent when conventional ion‐exchange purification procedures are applied to desilicified samples. In this study, we developed an improved purification method to determine HSEs in desilicified samples. This method enables the reduction of the ratios of isobaric and polyatomic interferences, relative to the measured intensities of HSE isotope masses, to less than a few hundred parts per million. Furthermore, the total procedural blanks are either comparable to or lower than conventional methods. Thus, this method allows accurate and precise HSE measurements in mafic and ultramafic geological samples, without the need for interference corrections. Moreover, the problem of increased interfering elements, such as Zr for Pd and Cr for Ru, is circumvented for the desilicified samples.
en-copyright=
kn-copyright=
en-aut-name=ZhouXiaoyu
en-aut-sei=Zhou
en-aut-mei=Xiaoyu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=TanakaRyoji
en-aut-sei=Tanaka
en-aut-mei=Ryoji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=YamanakaMasahiro
en-aut-sei=Yamanaka
en-aut-mei=Masahiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=SakaguchiChie
en-aut-sei=Sakaguchi
en-aut-mei=Chie
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
affil-num=1
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=3
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=4
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=5
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=highly siderophile elements
kn-keyword=highly siderophile elements
en-keyword=desilicification
kn-keyword=desilicification
en-keyword=isotope dilution method
kn-keyword=isotope dilution method
en-keyword=high resolution ICP-MS
kn-keyword=high resolution ICP-MS
en-keyword=N-TIMS
kn-keyword=N-TIMS
END
start-ver=1.4
cd-journal=joma
no-vol=304
cd-vols=
no-issue=
article-no=
start-page=109402
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=202009
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Mineralogical alterations in calcite powder flooded with MgCl2 to study Enhanced Oil Recovery (EOR) mechanisms at pore scale
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Seawater injection into chalk-reservoirs on the Norwegian Continental Shelf has increased the oil recovery and reduced seabed subsidence, but not eliminated it. Therefore, understanding rock?fluid interactions is paramount to optimize water injection, predict and control water-induced compaction.
Laboratory experiments on onshore and reservoir chalks have shown the need to simplify the aqueous chemistry of the brine, and also the importance of studying the effect of primary mineralogy of chalk to understand which ions interact with the minerals present. In this study, the mineralogy of the samples tested, are simplified. These experiments are carried out on pure calcite powder (99.95%), compressed to cylinders, flooded with MgCl2, at 130?°C and 0.5?MPa effective stress, for 27 and 289 days.
The tested material was analysed by scanning and transmission electron microscopy, along with whole-rock geochemistry. The results show dissolution of calcite followed by precipitation of magnesite. The occurrence and shape of new-grown crystals depend on flooding time and distance from the flooding inlet of the cylinder. Crystals vary in shape and size, from a few nanometres up to 2?μm after 27 days, and to over 10?μm after 289 days of flooding and may crystallize as a single grain or in clusters.
The population and distribution of new-grown minerals are found to be controlled by nucleation- and growth-rates along with advection of the injected fluid through the cores. Our findings are compared with in-house experiments on chalks, and allow for insight of where, when, and how crystals preferentially grow.
en-copyright=
kn-copyright=
en-aut-name=MindeMona W.
en-aut-sei=Minde
en-aut-mei=Mona W.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=MadlandMerete V.
en-aut-sei=Madland
en-aut-mei=Merete V.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=ZimmermannUdo
en-aut-sei=Zimmermann
en-aut-mei=Udo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=EgelandNina
en-aut-sei=Egeland
en-aut-mei=Nina
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=KorsnesReidar I.
en-aut-sei=Korsnes
en-aut-mei=Reidar I.
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=
en-aut-name=KobayashiKatsura
en-aut-sei=Kobayashi
en-aut-mei=Katsura
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=
en-aut-name=OtaTsutomu
en-aut-sei=Ota
en-aut-mei=Tsutomu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=
affil-num=1
en-affil=The National IOR Centre of Norway
kn-affil=
affil-num=2
en-affil=The National IOR Centre of Norway
kn-affil=
affil-num=3
en-affil=The National IOR Centre of Norway
kn-affil=
affil-num=4
en-affil=The National IOR Centre of Norway
kn-affil=
affil-num=5
en-affil=The National IOR Centre of Norway
kn-affil=
affil-num=6
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=7
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=8
en-affil=Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=Mineral replacement reactions
kn-keyword=Mineral replacement reactions
en-keyword=EOR
kn-keyword=EOR
en-keyword=Calcite
kn-keyword=Calcite
en-keyword=FE-SEM
kn-keyword=FE-SEM
en-keyword=FE-TEM
kn-keyword=FE-TEM
END
start-ver=1.4
cd-journal=joma
no-vol=20
cd-vols=
no-issue=7
article-no=
start-page=916
end-page=921
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200708
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=The Albedo of Ryugu: Evidence for a High Organic Abundance, as Inferred from the Hayabusa2 Touchdown Maneuver
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=The Hayabusa2 mission successfully collected samples from the asteroid Ryugu last year and will return these to Earth in December 2020. It is anticipated that the samples will enable the analysis of terrestrially uncontaminated organic matter and minerals. Such analyses are in turn expected to elucidate the evolution of organic matter through Solar System history, including the origination and processing of biogenically important molecules, which could have been utilized by the first organisms on Earth. In anticipation, studies have made predictions concerning the properties of Ryugu, including its composition. The spectral characteristics of Ryugu, such as albedo, have been employed to relate the asteroid to members of the carbonaceous chondrite group that have been identified on Earth. However, the recent Hayabusa2 touchdown highlights a disparity between the color of surfaces of displaced platy fragments, indicating a brightening trend for the surface exposed to space compared to that facing into the body. Here we present a mass balance calculation with reference to data from the literature, which indicates that Ryugu may contain a significantly higher abundance of organic matter (likely >50%) than the currently most accepted meteorite analogues. A high organic content may result in high levels of extractable organic matter for the second touchdown site, where the spacecraft sampled freshly exposed material. However, high abundances of insoluble aromatic/graphitic rich organic matter may be present in the first touchdown site, which sampled the surface of Ryugu that had been exposed to space. Moreover, we suggest that the potentially high organic abundance and the rubble-pile nature of Ryugu may originate from the capture of rocky debris by a comet nucleus and subsequent water-organic-mineral interactions and sublimation of water ice.
en-copyright=
kn-copyright=
en-aut-name=PotiszilChristian
en-aut-sei=Potiszil
en-aut-mei=Christian
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=TanakaRyoji
en-aut-sei=Tanaka
en-aut-mei=Ryoji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=KobayashiKatsura
en-aut-sei=Kobayashi
en-aut-mei=Katsura
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=KunihiroTak
en-aut-sei=Kunihiro
en-aut-mei=Tak
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
affil-num=1
en-affil=Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=3
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=4
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=5
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=Hayabusa2
kn-keyword=Hayabusa2
en-keyword=Ryugu
kn-keyword=Ryugu
en-keyword=Sample return
kn-keyword=Sample return
en-keyword=Organic matter
kn-keyword=Organic matter
en-keyword=Albedo. Astrobiology 20, 916?921
kn-keyword=Albedo. Astrobiology 20, 916?921
END
start-ver=1.4
cd-journal=joma
no-vol=334
cd-vols=
no-issue=
article-no=
start-page=105475
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=201911
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Tourmaline in a Mesoarchean pelagic hydrothermal system: Implications for the habitat of early life
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= The RNA World hypothesis requires the synthesis of RNA to allow the emergence of life on Earth. Hydrothermal systems have been proposed as potential candidates for constructing complex biomolecules. However, in order to successfully form RNA, it is necessary to stabilize ribose, a RNA carbohydrate component. Borate has been found to stabilize ribose. Therefore, boron rich hydrothermal systems are important environments concerning the origin of life on Earth.
The 3.2-Ga Dixon Island Formation of the West Pilbara Superterrane, Western Australia, is a volcano-sedimentary sequence. The Formation represents a Mesoarchean pelagic hydrothermal system, which formed adjacent to an immature island arc. Fine-grained tourmaline, in addition to biogenic carbonaceous matter and spherulitic and tubular bacteriomorphs, are found in black chert. A boron-rich environment was responsible for the formation of these deposits. To explore the implications of such a boron enriched environment on microbial activity, modes of occurrence and chemical compositions of the tourmaline were examined.
The tourmaline is schorl or dravite of the alkali tourmaline group and the boron isotope compositions range in δ11B from -7.3 to +2.6‰. The tourmaline occurs in microcrystalline quartz matrix of black chert veins that cross cut a volcanic unit and also in a bedded black chert, which overlays the volcanic unit. The volcanic unit contains highly altered zones with hydrothermal veins. The associated lithologic and stratigraphic features suggest that the black chert veins were the conduits for upward moving hydrothermal fluids, which reached the sea floor. Subsequently, the volcanic unit was covered by organic matter-rich cherty sediments that in part were fed, and/or altered, by the hydrothermal fluids.
These results suggest that the origin of boron enrichment to form Dixon Island tourmaline is not the associated sedimentary mineral assemblage, which includes diagenetic clay, low-grade metamorphic mica, and organic matter. Instead, the tourmaline was directly precipitated from hydrothermal fluid, enriched in boron. Furthermore, the hydrothermal fluids had already concentrated the boron, in the Mesoarchean pelagic system, prior to the apex of organic matter production and microbial activity. Our findings support a hypothesis that the boron-enriched hydrothermal environment aided the survival and evolution of early life.
en-copyright=
kn-copyright=
en-aut-name=OtaTsutomu
en-aut-sei=Ota
en-aut-mei=Tsutomu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=AiharaYuhei
en-aut-sei=Aihara
en-aut-mei=Yuhei
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=KiyokawaShoichi
en-aut-sei=Kiyokawa
en-aut-mei=Shoichi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=TanakaRyoji
en-aut-sei=Tanaka
en-aut-mei=Ryoji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
affil-num=1
en-affil=Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=Department of Earth and Planetary Sciences, Kyushu University
kn-affil=
affil-num=3
en-affil=Department of Earth and Planetary Sciences, Kyushu University
kn-affil=
affil-num=4
en-affil=Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=5
en-affil=The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=Mesoarchean
kn-keyword=Mesoarchean
en-keyword=Hydrothermal system
kn-keyword=Hydrothermal system
en-keyword=Early life
kn-keyword=Early life
en-keyword=Boron
kn-keyword=Boron
en-keyword=Tourmaline
kn-keyword=Tourmaline
END
start-ver=1.4
cd-journal=joma
no-vol=60
cd-vols=
no-issue=8
article-no=
start-page=1681
end-page=1715
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2019
dt-pub=20190912
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Transition from Plume-driven to Plate-driven Magmatism in the Evolution of the Main Ethiopian Rift
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= New K-Ar ages, major and trace element concentrations, and Sr-Nd-Pb isotope data are presented for Oligocene to recent mafic volcanic rocks from the Ethiopian Plateau, the Main Ethiopian Rift (MER), and the Afar depression. Chronological and geochemical data from this study are combined with previously published datasets to reveal secular variations in magmatism throughout the entire Ethiopian volcanic region. The mafic lavas in these regions show variability in terms of silica-saturation (i.e. alkaline and sub-alkaline series) and extent of differentiation (mafic through intermediate to felsic). The P-T conditions of melting, estimated using the least differentiated basalts, reveal a secular decrease in the mantle potential temperature, from when the flood basalt magmas erupted (up to 1600 degrees C) to the time of the rift-related magmatism (<1500 degrees C). Variations in the Sr-Nd-Pb isotopic compositions of the mafic lavas can account for the involvement of multiple end-member components. The relative contributions of these end-member components vary in space and time owing to changes in the thermal condition of the asthenosphere and the thickness of the lithosphere. The evolution of the Ethiopian rift is caused by a transition from plume-driven to plate-driven mantle upwelling, although the present-day mantle beneath the MER and the Afar depression is still warmer than normal asthenosphere.
en-copyright=
kn-copyright=
en-aut-name=FeyissaDejene Hailemariam
en-aut-sei=Feyissa
en-aut-mei=Dejene Hailemariam
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=
en-aut-name=KitagawaHiroshi
en-aut-sei=Kitagawa
en-aut-mei=Hiroshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=
en-aut-name=BizunehTesfaye Demissie
en-aut-sei=Bizuneh
en-aut-mei=Tesfaye Demissie
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=
en-aut-name=TanakaRyoji
en-aut-sei=Tanaka
en-aut-mei=Ryoji
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=
en-aut-name=KabetoKurkura
en-aut-sei=Kabeto
en-aut-mei=Kurkura
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=
en-aut-name=NakamuraEizo
en-aut-sei=Nakamura
en-aut-mei=Eizo
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=
affil-num=1
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=2
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=3
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=4
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=5
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
affil-num=6
en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University
kn-affil=
en-keyword=Ethiopian Plateau
kn-keyword=Ethiopian Plateau
en-keyword=Ethiopian rift
kn-keyword=Ethiopian rift
en-keyword=Afar depression
kn-keyword=Afar depression
en-keyword=mantle source
kn-keyword=mantle source
en-keyword=mantle melting
kn-keyword=mantle melting
END