論文 - 新城　竜一

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年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

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

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

日本地球化学会年会要旨集 ( 一般社団法人日本地球化学会 )  65 ( 0 ) 114   2018年

掲載種別: 研究論文（研究会，シンポジウム資料等）

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北部フォッサマグナ周辺のマントル物質の改変：起源マントルとスラブ溶融成分変化

岡村 聡, 稲葉 充, 新城竜一

月刊地球   40 ( 4 ) 225 - 233   2018年

掲載種別: 研究論文（その他学術会議資料等）

Spatial variations in dissolved rare earth element concentrations in the East China Sea water column.

Luong, L.D, Shinjo, R, Hoang, N, Shakirov, R.B, Syrbu, N

Marine Chemistry ( Marine Chemistry )  205   1 - 15   2018年 [ 査読有り ]

掲載種別: 研究論文（その他学術会議資料等）

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Gabbroic-dioritic dykes from the Sanadaj-Sirjan Zone: windows on Jurassic and Eocene geodynamic processes in the Zagros Orogen, western Iran

Deevsalar, R, Shinjo, R, Wang, K.-L, Yeganehfar, H, Neill, I

Journal of the Geological Society ( Journal of the Geological Society )  175 ( 6 ) 915 - 933   2018年 [ 査読有り ]

掲載種別: 研究論文（その他学術会議資料等）

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北部フォッサマグナ周辺のマントル物質の改変：起源マントルとスラブ溶融成分変化

新城 竜一

月刊地球   40   225 - 233   2018年

掲載種別: 研究論文（学術雑誌）

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首里城の大龍柱と伝えられる残欠の石質について

新城 竜一

沖縄県立博物館・美術館, 博物館紀要   11   11 - 14   2018年

掲載種別: 研究論文（学術雑誌）

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首里城の大龍柱と伝えられる残欠の石質について

宇佐美賢, 佐々木健志, 知念正昭, 新城竜一

沖縄県立博物館・美術館, 博物館紀要   ( 11 ) 11 - 14   2018年

掲載種別: 研究論文（その他学術会議資料等）

米山層火山岩類のSr, Nd, Hf同位体組成

相澤 正隆, 新城 竜一, 岡村 聡, 高橋 俊郎, 米山団体研究 グループ

日本地球化学会年会要旨集 ( 一般社団法人日本地球化学会 )  65 ( 0 ) 118 - 118   2018年

掲載種別: 研究論文（研究会，シンポジウム資料等）

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<p> 北部フォッサマグナ地域北東部に分布する米山層火山岩類(鮮新世-更新世)は，玄武岩から安山岩組成の火山岩からなり，5つの火山活動ステージに区分される．大部分の岩石は均質なSr, Nd, Hf同位体組成を示すが，第3ステージの岩石の一部は高Sr，低Nd，低Hf同位体組成を示し，分別結晶作用に加えて下部地殻物質の混染を受けた可能性がある．ただし，下部地殻の深度からもたらされた角閃石斑れい岩質捕獲岩は幅広いSr同位体組成を示すため，下部地殻の混染の程度を詳細に見積もるには，今後捕獲岩のHf同位体データを考慮して検討する必要がある．</p>

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北部フォッサマグナ米山層火山岩類のマグマプロセス—希土類元素組成からの制約—

相澤 正隆, 新城 竜一, 岡村 聡, 高橋 俊郎, 藤林 紀枝, 米山団体研究グループ

日本火山学会講演予稿集 ( 特定非営利活動法人 日本火山学会 )  2018 ( 0 ) 37 - 37   2018年

掲載種別: 研究論文（その他学術会議資料等）

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下北半島泊層火山岩類ボーリングコアの岩石学的検討

相澤 正隆, 稲葉 充, 岡村 聡, 新城 竜一

日本地質学会学術大会講演要旨 ( 一般社団法人 日本地質学会 )  2018 ( 0 ) 368 - 368   2018年

掲載種別: 研究論文（その他学術会議資料等）

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【災害のためプログラム中止】 平成30年北海道胆振東部地震により学術大会のプログラムが大幅に中止となりました．中止となったプログラムの講演要旨については，著者のプライオリティ保護の見地からJ-STAGEに公開し，引用可能とします．ただし，学術大会においては専門家による議論には供されていませんので「災害のためプログラム中止」との文言を付記します．（日本地質学会行事委員会）

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Tracing subducted sediment inputs to the Ryukyu arc-Okinawa Trough system: Evidence from thallium isotopes

Shu Y.

Geochimica et Cosmochimica Acta ( Geochimica et Cosmochimica Acta )  217   462 - 491   2017年11月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Sediments are actively subducted in virtually every arc worldwide. However, quantifying their contributions to arc lavas and thereby establishing budgets of how sediments participate in slab-mantle interaction is challenging. In this contribution we use thallium (Tl) abundances and isotopic compositions of lavas from the Ryukyu arc (including south Kyushu) and its back-arc basin, Okinawa Trough, to investigate the influence of sediments from arc to back-arc. We also present extensive geochemical data for sediments and altered oceanic crust (AOC) outboard of the northern (DSDP Sites 296, 442B, 443 and 444) and central (DSDP Sites 294 and 295) part of the Ryukyu arc. The Tl isotopic compositions of sediments change systematically from lighter outboard of northern Ryukyu arc to heavier outboard of central Ryukyu arc. The feature reflects the dominance of terrigenous material and pelagic sedimentation outboard of the northern and central Ryukyu arc, respectively. Central and northern sections of Ryukyu arc and Okinawa Trough display larger range of Tl isotopic variation than southern section, which is consistent with more pelagic provenance for sediments outboard of central and northern Ryukyu arcs than that of expected sediments outboard of southern Ryukyu arc. Identical Tl, Sr, Nd and Pb isotope variations are found when comparing arc and back arc lavas, which indicates that sediments fluxes also account for the Tl isotopic variations in the Okinawa Trough lavas. Two-end-member mixing models of Tl with Pb, Sr and Nd isotopes require sediment inputs of&lt; 1%, 0.1-1% and 0.3-2% by weight to the depleted mantle source to account for all these isotopic compositions of lavas from northern, central and southern portion of the Ryukyu arc and Okinawa Trough. Bulk mixing between mantle and sediment end members predict very similar sediment fluxes when using Tl, Sr, Nd and Pb isotopes, which indicates that fractionation of these elements must have happened after mixing between mantle and sediments. This conclusion is corroborated by model calculations of mixing between sediment melts with fractionated Sr/Nd ratios and mantle wedge, which show that no arc lava plot on such mixing lines. Thus bulk sediment mixing, rather than sediment melt, is required for the generation of the lavas from the Ryukyu arc and Okinawa Trough. The requirement of bulk sediment mixing occurring before trace element fractionation in the sub-arc mantle is consistent with models where melange layers form at the top of the slab and are the principle source material for arc lavas. In addition, the fact that sediment components observed in the Ryukyu arc and OkinawaTrough lavas are similar, suggests that transport of melange material to the source regions of the arc and back arc is equally efficient. This feature is most readily explained if melange material is transported from the slab as diapirs. (C) 2017 Elsevier Ltd. All rights reserved.

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Mesozoic–Cenozoic mafic magmatism in Sanandaj–Sirjan Zone, Zagros Orogen (Western Iran): Geochemical and isotopic inferences from Middle Jurassic and Late Eocene gabbros

Deevsalar R.

Lithos ( Lithos )  284   588 - 607   2017年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

One of the consequences of Neo-Tethys ocean subduction beneath the Central Iranian Micro-continent (CIMC) is the development of rare gabbroic intrusions in the Malayer-Boroujerd Plutonic Complex (MBPC) located in the Sanandaj-Sirjan Zone (SaSZ) of the Zagros Orogenic belt. The MBPC is a suite of extensive felsic and lesser mafic magmatic products in the northern SaSZ with geochemical signatures of arc-like magmatism during the Middle Jurassic (Ghorveh-Aligudarz arc) and intraplate type in the Late Eocene. Middle Jurassic gabbros (non-cumulate and cumulate) have low-Ti concentrations (&lt;1 wt.%) and quite uniform isotopic compositions (initial Sr-87/Sr-86: 0.7035-0.70593 and epsilon Nd(t): -6.18 to -0.7), enriched LILE relative to HFSE, variable fractionation between the LREE and HREE ((La/Yb)(cn) : 227-7.45) and both negative to positive Eu anomalies. These distinctive features of arc-type magmatism are consistent with a subduction-modified mantle source for these rocks. Trace element and REE models indicate similar to 15% melting of a metasomatized amphibole-bearing garnet-spinel lherzolite (gamet:spinel similar to 7:3) in the sub-arc mantle wedge. The cumulate gabbros and non-cumulates belong to common liquid line of descent, with complementary trace element patterns. Much of the variation between samples can be modeled by fractional crystallization (FC) of a common parent; only one cumulate gabbro from this suite exhibits isotopic evidence of contamination, probably by Rb-depleted crustal materials. The Late Eocene gabbros have relatively high-Ti (&gt;1 wt.%) and display isotopically depleted Sr-Nd values (initial Sr-87/Sr-86: 0.7044-0.7087, epsilon Nd(t): 1.9 -+3.2, barring one crustally-contaminated sample). OIB-like trace element characteristics such as enriched HFSE, and only minor enrichment of LILE and LREE, reflect a within-plate character and asthenospheric source. Trace element modeling indicates small degree melting (f(melting): 0.05) of upper mantle lherzolite (garnet:spinel similar to 3:1) followed by higher degree melting (f(melting): 0.15) at shallower depths (garnet:spinel similar to 4.5:2). The Eocene parental magma underwent FC of olivine and clinopyroxene. We propose that Eocene asthenospheric upwelling was triggered by slab tearing in response to slab-rollback, which is elsewhere reported to have triggered a 'flare-up' of extension-related magmatism across Iran. Three stages of tectono-magmatic evolution in the Ghorveh-Aligudarz arc segment of the N-SaSZ are represented by: 1) arc-like magmatism during active subduction of the Neo-Tethys seaway at Middle Jurassic, 2) magmatic quiescence during an interval of shallow-angle or highly oblique subduction during the Cretaceous-Paleocene, and 3) asthenosphere melting during slab tearing shortly before the onset of the Arabia-Eurasia collision. (C) 2017 Elsevier B.V. All rights reserved.

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Petrologic and geochemical characterization of rift-related magmatism at the northernmost Main Ethiopian Rift: Implications for plume-lithosphere interaction and the evolution of rift mantle sources

Feyissa D.

Lithos ( Lithos )  282   240 - 261   2017年06月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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In this paper, we present petrography, K-Ar ages, whole-rock major- and trace-element concentrations, and Sr-Nd-Hf-Pb isotopic ratios of volcanic rocks from Debre Birhan area in the northernmost Main Ethiopian Rift (MER). The K-Ar ages of the mafic series range from 27 to 0.25 Ma, and two felsic rocks yield ages of 0.93 and 0.23 Ma. The mafic volcanics are classified into older and younger series based on their K-Ar ages. The Mg-numbers (Mg# &lt; 60) of both mafic series, along with low Ni and Cr contents, clearly indicate that these lavas have undergone fractionation en route to the surface. Geochemical and isotopic compositions of the older and younger mafic lavas indicate that crustal contamination did not play a significant role in the evolution of their magmas, hence reflect the geochemical characteristics of the sources. The older and younger mafic volcanic rocks display contrasting trace element and isotopic signatures. The older lavas have higher La/Nb, Zr/Nb, Ba/Nb and Sr-87/Sr-86(i) (0.70445-0.70681) and lower epsilon(Hf) (-2.58 to + 6.01) and epsilon(Nd) ( -1.25 to +3.43) and less radiogenic Pb isotopic ratios (Pb-206/(204)Pbi = 17.82-18.64, except TG-54 = 19.1) relative to the younger mafic lavas. Correlations among isotopic ratios and trace element concentrations provide evidence for the involvement of at least three major end-member components (C-1, C-2, and C-3) in the petrogenesis of these mafic lavas. The C-1 end-member component contributes dominantly to younger mafic lavas, and has isotopic composition similar to the common component 'C' deduced from oceanic basalts. The second end-member component (C-2) is represented by lavas near the transition between older and younger, and has isotopic composition similar to that of the seafloor basalts of the Red Sea and the Gulf of Aden. The third end-member component (C-3) is prominent in the older mafic series, and similar isotopically to Pan-African lithosphere. The younger felsic volcanic rocks generally have higher Sr-87/Sr-86(i) (0.70395-0.70689) than younger mafic series (0.70366-0.70454) but Nd, Hf and Pb isotopic ratios similar to those of the younger mafic lavas. The element concentrations and Sr, Nd, Hf and Pb isotopic compositions of the younger felsic rocks are explained by fractional crystallization of mafic melts in shallow-level magma chambers accompanied by limited assimilation of crustal material. Low degrees of partial melting of existing mafic underplate can account for the genesis of the least differentiated (intermediate) lavas, but failed to explain highly evolved younger felsic rocks. (C) 2017 Elsevier B.V. All rights reserved.

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Contribution of slab-derived fluid and sedimentary melt in the incipient arc magmas with development of the paleo-arc in the Oman Ophiolite

Kusano Y.

Chemical Geology ( Chemical Geology )  449   206 - 225   2017年01月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Major-element and trace-element geochemistry of fresh volcanic glass, and the whole-rock Hf and Nd isotopic compositions of volcanic rocks from the Oman Ophiolite were used to understand the extent to which slab-derived fluids and melts were involved in magma generation during incipient arc development. The spreading stage (V1) samples have trace-element characteristics similar to those of mid-ocean-ridge basalts, with Hf and Nd isotopic compositions of the Indian mantle domain. The incipient arc stage (V2) volcanic glasses have lower abundances of high field strength elements (HFSEs) and middle and heavy rare earth elements (MREE5 and HREES), and higher abundances of large ion lithophile elements (LILEs) than the V1 glasses. Progressive increases in B, Pb, and LILEs in the V2 stage glasses with age indicate an increasing contribution of slab-derived fluids from earlier arc tholeiite (LV2) to later boninite (UV2). The LV2 was generated by the contribution of amphibolite-derived fluid. The UV2 is subdivided into low-Si UV2 and high-Si UV2 magmas, with the former having lower SiO2, and LILE, and higher Na2O, HFSE and REE concentrations than the latter. The low-Si UV2 magma was generated with the involvement of high-temperature slab-derived fluid. In contrast, the high-Si UV2 shows a spoon-shaped trace-element pattern and Hf and Nd isotope chemistry, indicating the involvement of sediment melt in its magma genesis. Decreasing HFSEs and HREEs in the magmas with age indicate progressive depletion of the source mantle during the V2 arc magmatism, suggesting an absence of convection in the mantle wedge that resulted from subduction of a hot, buoyant slab beneath young, hot lithosphere. (C) 2016 Elsevier B.V. All rights reserved.

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Pollution assessment of various heavy metals in the surface sediment of Kendari Bay, Indonesia

新城 竜一

Nature Environment and Pollution Technology   16   1067 - 1074   2017年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Pollution assessment of various heavy metals in the surface sediment of Kendari Bay, Indonesia

Armid, A, Shinjo, R, Sabarwati, S.H, Ruslan, R

Nature Environment and Pollution Technology   16 ( 4 ) 1067 - 1074   2017年 [ 査読有り ]

掲載種別: 研究論文（その他学術会議資料等）

北部フォッサマグナ周辺の新生代火成活動と背弧海盆テクトニクス

岡村聡, 稲葉充, 足立佳子, 新城竜一

地球科学 ( 地学団体研究会 )  71 ( 2 ) 65 - 73   2017年 [ 査読有り ]

掲載種別: 研究論文（その他学術会議資料等）

地質調査で採取された堆積物試料中の間隙水の地球化学的解析

石橋 純一郎, 土岐 知弘, 新城 竜一

SIP 『次世代海洋資源調査技術』（海のジパング計画）　海底熱水鉱床の調査技術プロトコル   -   61   2017年

掲載種別: 研究論文（学術雑誌）

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地質調査で採取された堆積物試料中の間隙水の地球化学的解析

石橋純一郎, 正木裕香, 岡村慶, 野口拓郎, 土岐知弘, 新城竜一

SIP 『次世代海洋資源調査技術』（海のジパング計画） 海底熱水鉱床の調査技術プロトコル     2017年

掲載種別: 研究論文（その他学術会議資料等）