Published Papers - SHINJO Ryuichi

Hf and W fractionation calculation between liquid metal and liquid silicate and resultant core-mantle interaction signature on the 182W isotope of the Ethiopian basalts

Suzuki Katsuhiko, Takamasa Asako, Tsuchiya Taku, Fukami Yusuke, Orihashi Yuji, Shinjo Ryuichi

Abstracts of Annual Meeting of the Geochemical Society of Japan ( GEOCHEMICAL SOCIETY OF JAPAN )  68 ( 0 ) 115   2021

Type of publication: Research paper (research society, symposium materials, etc.)

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"Petrogenesis of gabbroic rocks from the Malayer plutonic complex (Sanandaj-Sirjan zone, west Iran)": Discussion

Deevsalar, R; Shinjo, R

PERIODICO DI MINERALOGIA ( Periodico di Mineralogia )  89 ( 3 ) 281 - 284   2020.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Evaluation of geochemical records as a paleoenvironmental proxy in the hypercalcified demosponge Astrosclera willeyana

Ryuji Asami, Akira Kinjo, Daiki Ohshiro, Tohru Naruse, Masaru Mizuyama, Ryu Uemura, Ryuichi Shinjo, Yuji Ise, Yoshihisa Fujita, Takashi Sakamaki

Progress in Earth and Planetary Science ( Springer Science and Business Media LLC )  7 ( 1 )   2020.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Petrogenesis of gem sapphire in a pegmatite-aplite vein from the Alvand batholith, Western Iran

Sheikhi Gheshlaghi R.

Mineralogy and Petrology ( Mineralogy and Petrology )  114 ( 6 ) 501 - 513   2020.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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High‐Resolution Evidence for Middle Holocene East Asian Winter and Summer Monsoon Variations: Snapshots of Fossil Coral Records

Ryuji Asami, Natsumi Yoshimura, Hiroto Toriyabe, Shogo Minei, Ryuichi Shinjo, Chuki Hongo, Takashi Sakamaki, Kazuhiko Fujita

Geophysical Research Letters ( American Geophysical Union (AGU) )  47 ( 16 )   2020.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Barium isotope systematics of subduction zones

Nielsen S.G.

Geochimica et Cosmochimica Acta ( Geochimica et Cosmochimica Acta )  275   1 - 18   2020.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Subduction zones are the focal points of mass transfer between the surface and deep Earth. Despite their significance, there remains substantial debate regarding the specific mechanisms of material transport from the slab to the overlying magmatic arc. Broadly, models accounting for slab material transport focus on the relative sequence of events promoting arc volcanism and, in particular, whether mobilization of the down-going slab leads or lags mixing with the mantle wedge. To address these uncertainties, we outline the utility of barium (Ba) isotope mass balance in subduction zones as a means to test different slab material transport models. Barium is a highly fluid-mobile element that is significantly enriched in arc magmas and is thus thought to be a sensitive tracer of slab material transport in arcs.We also present qualitative Ba isotopic mass balances for two well-characterized subduction zones the Aleutian and Ryu- kyu magmatic arcs by analyzing the Ba isotope systematics of their respective subduction inputs and outputs. Despite the narrow (and similar) Ba-isotope range of slab inputs to both systems, we find that erupted magmas exhibit systematic variations indicative of a small negative isotope fractionation during Ba mobilization (approximate to 20-40 ppm AMU(-1)). We suggest that AOC (altered oceanic crust) is not the principal source of these negative isotope values using other geochemical parameters (e.g., Rb/Ba, Pb isotopes), and infer that the Ba isotope composition of AOC though contributing a minor amount of Ba in these systems is isotopically heavier than the overlying sediment package and the depleted mantle. Altogether, these findings are significant as they indicate that the magnitude of isotope fractionation associated with Ba mobilization is small relative to the likely isotopic contrast between subduction inputs in other subduction zones, such as beneath areas of strong ocean upwelling (e.g., South Sandwich, Kamchatka). Thus, we propose that the Ba isotope composition of erupted arc magmas holds great promise for constraining the importance of different slab components, which could help address uncertainties regarding the mechanism of slab material transport in subduction zones. (C) 2020 Elsevier Ltd. All rights reserved.

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Geochemical characteristics of mafic and felsic igneous rocks (1.9–1.75 ga) in the lesser Himalaya: Regional variation and its implications for tectonic setting

Shinjo R.

Island Arc ( Island Arc )  29 ( 1 ) 1 - 14   2020.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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“Petrogenesis of gabbroic rocks from the Malayer plutonic complex (Sanandaj-Sirjan zone, west Iran)”: Discussion

Reza Deevsalar, Ryuichi SHINJO

Periodico di Mineralogia   89   281 - 284   2020 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Geochemical and isotopic constraints on the evolution of magma plumbing system at Damavand Volcano, N Iran

Eskandari, A, Deevsalar, R, De Rosa, R, Shinjo, R, Donato, P, Neill, I

Lithos   354-355   2019.10 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

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Pleistocene basaltic volcanism in the Kr_ng N_ area and vicinity, Dac Nong Province (Vietnam)

Nguyen Hoang, Shinjo Ryuichi, La The Phuc, Le Duc Anh, Tran Thi Huong, Pecskay Zoltan, Dao Thai Bac

JOURNAL OF ASIAN EARTH SCIENCES   181   103903   2019.09 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

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Geochemical fractions and modeling adsorption of heavy metals into contaminated river sediments in Japan and Thailand determined by sequential leaching technique using ICP-MS

Wijaya Anugrah Ricky, Ohde Shigeru, Shinjo Ryuichi, Ganmanee Monthon, Cohen Michael Dustin

ARABIAN JOURNAL OF CHEMISTRY   12 ( 6 ) 780 - 799   2019.09 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

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Features in REE and Methane Anomalies Distribution in the East China Sea Water Column: a Comparison with the South China Sea

Le Due Luong, Shakirov Renat B, Nguyen Hoang, Shinjo Ryuichi, Obzhirov Anatoly, Syrbu Nadezhda, Shakirova Maria

WATER RESOURCES   46 ( 5 ) 807 - 816   2019.09 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

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Biotite compositional variations - A physicochemical approach to investigate crustal involvement and ore potential in Middle Jurassic plutonic rocks from the Malayer-Boroujerd Plutonic complex, W Iran

Yeganehfar Hadi, Deevsalar Reza, Ahadnejad Vahid, Shinjo Ryuichi, Neill Iain

NEUES JAHRBUCH FUR MINERALOGIE-ABHANDLUNGEN   196 ( 1 ) 19 - 42   2019.06 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

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Highly precise ¹⁸²W/¹⁸⁴W of the Ethiopian basalts and Aden Bay MORB

Suzuki Katsuhiko, Takamasa Asako, Fukami Yusuke, Iizuka Tsuyoshi, Orihashi Yuji, Shinjo Ryuichi

Abstracts of Annual Meeting of the Geochemical Society of Japan ( GEOCHEMICAL SOCIETY OF JAPAN )  66 ( 0 ) 214 - 214   2019

Type of publication: Research paper (research society, symposium materials, etc.)

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Theme session “Marine science researches of Okinawa Research Core for Highly Innovative Discipline Science (ORCHIDS) project"

NAKAMURA Takashi, REIMER James Davis, SHINJO Ryuichi, NAKAMURA Mamoru, TANAKA Atsuko, WEE Hin Boo

Journal of the Japanese Coral Reef Society ( The Japanese Coral Reef Society )  21 ( 1 ) 1 - 12   2019

Type of publication: Research paper (scientific journal)

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High-K tholeiitic volcanic rocks of Yoneyama Formation from the northern Fossa Magna, central Japan: Derivative from high water content magma

AIZAWA Masataka, OKAMURA Satoshi, SHINJO Ryuichi, TAKAHASHI Toshiro, Yoneyama Research Group

Japanese Magazine of Mineralogical and Petrological Sciences ( Japan Association of Mineralogical Sciences )  48 ( 1 ) 1 - 24   2019

Type of publication: Research paper (other science council materials etc.)

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<p>Late Pliocene-Early Pleistocene igneous rocks of Yoneyama Formation from the northern Fossa Magna region, central Japan, consist of basaltic to andesitic rocks and small intrusive rocks; they contain frequently hornblende (Hbl) gabbroic xenoliths and Hbl xenocrysts. Based on field data, together with petrographic, geochemical, and geochlonological descriptions, the volcanism comprised 5 stages. The rocks at the Ogamidake, the 1st and 3rd stages are tholeiitic rock series (TH), whereas calc-alkalic rock series (CA) are dominated at the 2nd and 4th stages. All rocks are characterized by high-K content and contain pargasitic Hbl phenocrysts in both rock series. Estimation using Ca-amphibole geobarometer suggests that Hbls have crystallized at depths of lower crust. Existence of Hbl and high An content of plagioclase (～ An₉₀) in both rock series imply that both magmas are rich in H₂O. Estimated H₂O contents are ～ 5 wt% for both TH and CA magmas. Based on mineral texture, <i>P-T</i> estimation and major-trace elements modeling, we infer that cryptic fractionation of Hbl can produce the TH magma trend. Our model is incompatible with general model that TH magma originate from anhydrous or low H₂O content magma.</p>

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Cryptic amphibole fractionation in Umikawa volcanic rocks, northern Fossa Magna, central Japan

Aizawa Masataka, Shinjo Ryuichi, Okamura Satoshi, Miyagi Isoji

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN ( The Volcanological Society of Japan )  2019 ( 0 ) 26 - 26   2019

Type of publication: Research paper (other science council materials etc.)

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Breakdown of residual zircon in the Izu arc subducting slab during backarc rifting

Hirai Y.

Geology ( Geology )  46 ( 4 ) 371 - 374   2018.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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High field strength elements (HFSEs) are depleted in subduction-related melts because of the residual minerals in the slab. It has been suggested that high slab-surface temperatures cause the breakdown of residual zircon in the slab. In this study, we found that two geochemical types can be identified within basalts from the active backarc rift zone of the Izu arc (northwest Pacific Ocean). Low-Zr/Y basalts (LZBs) were collected from across the entire area of the active rift zone, whereas the high-Zr/Y basalts (HZBs) were identified only at the Sumisu Rift. Although enrichment of large-ion lithophile elements (LILEs) and Nb-Ta depletion are recognized in both types, a minimal negative Hf concentration anomaly (Hf/Hf* = 0.98) characterizes the HZB. In Nd-Hf isotope space, the HZB lies close to the Indian/Pacific mantle boundary, displaced from the LZB. Variations in Nb/Yb and Zr/Yb indicate differences in the fertility and/or degree of melting of source mantle that can explain the HFSE systematics in the LZB, but not in the HZB. Geochemical modeling demonstrates that mixtures of mantle wedge and ~2% slab-derived melt, not in equilibrium with residual zircon, produces the observed trace-element and isotopic characteristics in the HZB. Moreover, the range of occurrence of the HZB corresponds with the range in seismic low-velocity anomalies in the upper slab. We suggest that asthenospheric material injected into the mantle wedge beneath the Sumisu Rift is a possible heat source for the breakdown of residual zircon in the slab.

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Subduction-related mafic to felsic magmatism in the Malayer–Boroujerd plutonic complex, western Iran

Deevsalar R.

Swiss Journal of Geosciences ( Swiss Journal of Geosciences )  111 ( 1-2 ) 269 - 293   2018.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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The Malayer–Boroujerd plutonic complex (MBPC) in western Iran, consists of a portion of a magmatic arc built by the northeast verging subduction of the Neo-Tethys plate beneath the Central Iranian Microcontinent (CIMC). Middle Jurassic-aged felsic magmatic activity in MBPC is manifested by I-type and S-type granites. The mafic rocks include gabbroic intrusions and dykes and intermediate rocks are dioritic dykes and minor intrusions, as well as mafic microgranular enclaves (MMEs). MBPC Jurassic-aged rocks exhibit arc-like geochemical signatures, as they are LILE- and LREE-enriched and HFSE- and HREE-depleted and display negative Nb–Ta anomalies. The gabbro dykes and intrusions originated from metasomatically enriched garnet-spinel lherzolite [Degree of melting (fmel) ~ 15%] and exhibit negative Nd and positive to slightly negative εHf(T) (+ 3.0 to − 1.6). The data reveal that evolution of Middle Jurassic magmatism occurred in two stages: (1) deep mantle-crust interplay zone and (2) the shallow level upper crustal magma chamber. The geochemical and isotopic data, as well as trace element modeling, indicate the parent magma for the MBPC S-type granites are products of upper crustal greywacke (fmel: 0.2), while I-type granites formed by partial melting of amphibolitic lower crust (fmel: 0.25) and mixing with upper crustal greywacke melt in a shallow level magma chamber [Degree of mixing (fmix): 0.3]. Mixing between andesitic melt leaving behind a refractory dense cumulates during partial crystallization of mantle-derived magma and lower crustal partial melt most likely produced MMEs (fmix: 0.2). However, enriched and moderately variable εNd(T) (− 3.21 to − 4.33) and high (87Sr/86Sr)i (0.7085–0.7092) in dioritic intrusions indicate that these magmas are likely experienced assimilation of upper crustal materials. The interpretations of magmatic activity in the MBPC is consistent with the role considered for mantle-derived magma as heat and mass supplier for initiation and evolution of magmatism in continental arc setting, elsewhere.

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The processes of alteration of volcanic rocks under the influence of the fumarolic gases in the Tatun Volcano Group, Taiwan

SONG Ke―Han, LIU Chia―Mai, KUO Ching―Huei, TSAI Yu―Wei, SHINJO Ryuichi

Abstracts of Annual Meeting of the Geochemical Society of Japan ( GEOCHEMICAL SOCIETY OF JAPAN )  65 ( 0 ) 114   2018

Type of publication: Research paper (research society, symposium materials, etc.)

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<p>The purpose of this study is to examine the processes of alteration under the influence of fumarolic gases by the comparison of variations in chemical compositions of the series of alteration products from several loci found in the Tatun Volcann Group (TVG), Taiwan. 26 rock samples are collected from Longenku and Liuhunagku, which are both active volcanic gas emission areas in the TVG, Taiwan. Samples are then analyzed by Scanning Electron Microscope, polarizing microscope, X-ray Diffractometer, Energy-dispersive X-ray spectroscopy and Energy Dispersive X-Ray Fluorescence to establish the linkage.The preliminary results show that there are wo types of the fumarolic alteration rocks were found in this study. Samples, taken away from fumaroles, consist of augite, hypersthene, hornblende and plagioclase with relative lower content of silica (up 54%) and no sulfur. On the other hand, samples, taken near fumaroles, consist of mainly opal, cristobalite and few plagioclases with relative higher content of silica (up to 90%) and sulfur elements. It suggests that volcanic gas such sulfur replaces magnesium and sodium in rock to make silica content increased in volume. This is the first report of this finding in TVG, Taiwan.</p>

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