記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

DOI： 10.5575/geosoc.2024.0009

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

<p><b>１．はじめに</b> 　著者らは，海底地すべり発生メカニズムについての研究を進めている^[1～3]．その一環として実施した富山県上市町の稲村露頭（南北約80 m，東西約70 m，最大比高約30 m）の調査では，一般的な地質調査ではあまり用いられない手法を活用^[3]し成果を得た^[4]ので概要を報告する．</p><p></p><p><b>２．手法</b></p><p><u>(1) 覚書締結：</u>調査対象は私有地に人造された露頭であることから，地権者の理解と賛同を得るため，調査に先立って学術的・普及活動上の意義について説明を行なった．地権者との交渉には，地元のジオパーク協会の協力を得た。以上の関係は，地権者（甲），地元協力者（乙），研究代表者が所属する研究機関（丙）の<b>三者による覚書</b>として締結された．覚書は，甲は甲が所有する対象地を，乙および丙が学術研究，普及活動等に活用することを認める内容となっている^[5]．</p><p><u>(2) 調査準備作業：</u>調査に先立ち，重機等を導入して露頭を覆う<b>灌木や下草類の伐採</b>と露頭前面下部に堆積した<b>崖錐被覆物の除去</b>を行った．また，露頭高所の調査を行うための仮設階段を設置した．これら各種土木作業等は，ジオパーク協会が地元町役場から紹介された地元の土木建設業者に依頼した．</p><p><u>(3) 地質調査：</u>露頭低所および仮設階段で登坂できる範囲に対しては，一般的な踏査による岩相層序解析，ならびに堆積相解析を実施した．大露頭において，地質学的注目点と空撮写真（後述）との対照を容易にするため，<b>測点明示釘</b>と樹脂製保持板（直径26mm）を注目点毎に設置した．また，詳細な堆積構造および変形構造を観察するため^[6]，<b>ディスクグラインダー</b>等を用いて一部露頭面の研磨を行なった．各岩石試料採取では<b>削岩機</b>（電気ピック），<b>電動ダイヤモンドカッター</b>，<b>エンジンカッター</b>等を活用した．</p><p><u>(4) トレンチ掘削：</u>地すべり層の三次元的な分布を追跡するため，また，地すべり層の基底面（すべり面）を含む新鮮な大型試料を採取するため，調査地中央部に幅約1.5m，長さ約10m，深さ約1.2mの<b>トレンチを掘削</b>した．</p><p><u>(5) 高所地質調査：</u>露頭高所に対しては，<b>高所作業車</b>（３段ブーム、最長約30m）を用いて研究者自身が近接肉眼観察し，岩相層序解析および堆積相解析を実施した．</p><p><u>(6) 空中写真撮影：</u>露頭の全体像の把握，露頭高所の観察，ならびに三次元デジタル地質モデル製作等を目的として，<b>ドローン</b>を用いた空中写真および動画撮影を行なった．第一段階では，鉛直上空および露頭面に直角となる斜め上空からのシリーズ画像を撮影し，露頭全体で約600枚の画像を得た．これらを三次元モデリングソフト「pix4Dmapper」に取り込んで<b>三次元地質モデル</b>化し，パソコン上での露頭全体像の把握に用いた．第二段階では、より高解像度のシリーズ画像を1,000枚以上撮影した．ドローンオペレーションは，地元および関西圏の専門業者に委託した．</p><p><u>(7) 三次元地質モデル製作：</u>第二段階のドローン画像からは，Metashapeモデルを作成した．このモデルは，<b>Agisoft Viewer</b>（フリーウェア）に読み込むことで，パソコン上で自由に回転，拡大縮小が可能である．さらに，解釈線を書き加えることができモデルデータとともに回転，拡大縮小できることから，全ての形態的な特徴を，肉眼観察点を起点として同モデル上で追跡し一括して整理した．</p><p></p><p><b>３．結果</b></p><p>　稲村露頭の折戸凝灰岩部層は前期中新世の火山砕屑岩類からなり^[7]，下位からA～Gの7ユニット（A, E～G：凝灰岩および凝灰角礫岩，B～D：凝灰質砂岩泥岩互層）に区分される．8層（D1～8）の凝灰質砂岩鍵層と挟在する凝灰質泥岩層からなるユニットDは，露頭北部では南方向への滑動により布団を畳むように折り曲げられ，褶曲軸面付近に形成される低角逆断層によって上盤側が下流へ衝上して，8層全体ないしその一部，ならびに逆転した一部が繰り返すことによって層厚を増している．ユニットEの凝灰岩および凝灰角礫岩中には，直下のユニットD上部から剥離された砂岩泥岩互層がブロック状，スランプ状に変形して取り込まれている． </p><p></p><p><b>謝辞：</b>英修興産有限会社，立山黒部ジオパーク協会の諸氏，有限会社きんた，鉄建建設株式会社に心より感謝する．なお，当該調査には科研費B（19H02397）の一部を使用した． </p><p></p><p><b>文献：</b> <b>[1]</b> 荒戸, 2018, 地質学会要旨, 110, <b>[2]</b> 荒戸, 2022, 石技誌, 87, 136, <b>[3]</b> 荒戸他, 2023, 堆積学会要旨, 9, <b>[4]</b> 荒戸他, 2023, 地質学会要旨, T-6-P20, <b>[5]</b> 金子他, 2023, 地質学会要旨, T-3-O-4, <b>[6]</b> 荒戸他, 2024, 地質雑, 130, 167, <b>[7]</b> 金子, 2001, 地質雑, 107, 729.</p>

DOI： 10.14863/geosocabst.2024.0_268

CiNii Research

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

<p><b>１．はじめに</b></p><p>　著者らは，海底地すべりの堆積学的な理解と運動学的なモデルの構築を目的に研究を進めている^[1など]．その一環として，富山県上市町の稲村露頭（南北約80 m，東西約70 m，最大比高約30 m）に分布する下部中新統稲村水中地すべり堆積物の内部変形構造の調査を実施している^[1～4]．その結果，滑動および変形様式が明らかになってきたので概要を報告する．</p><p></p><p>２．手法</p><p>　一般的な岩相層序ならびに堆積相解析に加え，詳細な堆積構造および変形構造を観察するため一部露頭面の研磨を行なった^[1]．その結果に基づき，滑動体を構成する砂岩層全８層（鍵層D1～D8）を区別し，露頭全体にわたって追跡した^[2]．鍵層砂岩の追跡は，肉眼観察地点を起点としてドローン画像から作成した三次元モデル上で行った^[4]．露頭高所については，高所作業車を用いた近接肉眼観察を併用した^{[1, 2]}．</p><p></p><p>３．結果（図参照）</p><p><u>(1) 層序・構造：</u>下部中新統折戸凝灰岩部層は，前～中期中新世の日本海拡大期に富山県から能登半島にかけて形成された北東－南西方向のリフト帯^[5など]南東縁に堆積した複数の単源火山砕屑岩類と関連堆積物からなる福平層の一部層であり，調査地では堆積後の後背地の隆起によって北～北西に約10～25度傾斜している^[6]．</p><p><u>(2) 岩相・ユニット区分：</u>稲村露頭の折戸凝灰岩部層は，岩相の特徴等に基づき下位からA～Gの7ユニットに区分される．</p><p><b>A：</b>塊状無層理の凝灰岩・凝灰角礫岩層からなる．</p><p><b>B, C：</b>プロデルタ成の凝灰質砂岩泥岩互層からなり，Aを覆う．砂岩・泥岩とも数cm～数10cmの層厚を有し，堆積時のslide等による変形は受けていない．</p><p><b>D：</b>Cを覆い，B，Cとほぼ同等の岩相を有する．ユニット内の逆断層より北側は激しい変形を受けているが，南側ではほとんど変形を受けておらず下位ユニットと調和的な走向傾斜を有する．</p><p><b>E：</b>凝灰岩，凝灰角礫岩の基質に，D上部の砂岩泥岩互層，泥岩などが変形してスランプ状，もしくはブロック状に取り込まれている．D由来のブロックの量および変形度合いは場所によって大きく異なる．</p><p><b>F, G：</b>凝灰岩，凝灰角礫岩からなり，Eを覆う．場所によってE上部の堆積物がF基底面を突き破ってF内に取り込まれている場合がある．</p><p><u>(3) ユニットDの変形様式：</u>Dの互層は，堆積学的特徴の異なるD1～D8の8層の凝灰質砂岩鍵層と挟在する凝灰質泥岩層からなる．砂岩層の層厚はそれぞれ12～52cm程度で，基底部の極粗粒から細粒へ上方細粒化し凝灰質泥岩層へ漸移する．凝灰質泥岩層は，見かけ上，12～60cm程度の層厚をもつ．露頭北部の同ユニットは，南方向への滑動により布団を畳むように折り曲げられ，褶曲軸面付近に形成される低角逆断層によって上盤側が下流へ変位して，8層全体ないしその一部，ならびに逆転した一部が繰り返すことによって層厚を増している．</p><p></p><p>４．稲村水中地すべりの滑動・変形モデル</p><p>　以上の観察結果を合理的に説明する滑動・変形モデルとして，以下のような過程を検討中である．</p><p><b>[a] </b>F（or G）堆積後の早い時期にD基底の泥岩層中にすべり面が形成され，ある場所から上流側が南へ傾斜する当時の斜面下方へ滑動を開始する，</p><p><b>[b]</b> 滑動開始当初，D互層は地すべり先端部にランプ背斜を形成して互層の一部が下流側の滑動しないDに乗り上げて滑動による短縮を解消する，</p><p><b>[c]</b> 短縮が進行するとランプ背斜は横臥褶曲に成長し，それでも短縮量を補償しきれなくなるとすべり面が上位へ分岐し低角逆断層となってさらに乗り上げていく，</p><p><b>[d]</b> さらに滑動が継続し短縮量が増えると，新たなランプ背斜・横臥褶曲が順次上流側に形成され（オーバーステップ状），こうした変形が累積することでDの層厚が不均質となる，</p><p><b>[e]</b> Dの層厚が不均質化することでE以上の上載圧力に不均衡が生じて低比重のDとより高比重の上位層との境界面が不安定になり，互層上部の一部が変形しながらEの凝灰岩中に取り込まれていく，</p><p><b>[f]</b> Eと上位のFの境界面も不安定になるが，両ユニット間の比重差は大きくないため，大規模な取り込みには発達しない．</p><p></p><p>謝辞：英修興産有限会社，立山黒部ジオパーク協会の諸氏，有限会社きんた，鉄建建設株式会社に心より感謝する．なお，当該調査には日本学術振興会科学研究費基盤研究(B)（一般）（19H02397）の一部を使用した．</p><p></p><p><b>文献：[1]</b>荒戸ほか, 2023, 堆積学会要旨, 9-10, <b>[2]</b>荒戸ほか, 2023, 地質学会要旨, T-6-P20, <b>[3]</b>金子ほか, 2023, 地質学会要旨, T-3-O-4, <b>[4]</b>荒戸ほか, 2024, 地質雑, 130, 167-168, <b>[5]</b>竹内, 2021，地質雑, 127, 145-164, <b>[6]</b>金子, 2001, 地質雑, 107, 729-748.</p>

DOI： 10.14863/geosocabst.2024.0_243

CiNii Research

出版者・発行元：Acta Astronautica  

The regolith on the Earth's Moon has been attracting attention from the perspective of understanding the planetary surface processes and procuring in-situ resources. However, very few studies have investigated the hydraulic properties of the lunar regolith, which should pose one of the most significant physical properties for understanding the lunar surface processes and evaluating regolith utilizations. In this paper, we study the water permeability of the surficial regolith layer on sunlit lunar highlands using the lunar highlands regolith simulant LHS-1. We measure the water permeability of LHS-1 at packing fractions of 0.49–0.60 by simulating lunar gravitational environments and evaluating the influences of freeze-thaw, which is expected to occur on the sunlit lunar highland surfaces. Our results indicate that the water permeability of lunar highland regolith is one to two orders of magnitudes lower than that of fine silica sands and monodisperse spherical glass beads at the given packing fraction. The low water permeability of lunar highland regolith attributes to the regolith particles having irregular and angular shapes with sharp edges and micron-sized chunks due to the least weathering, unlike soil particles on the Earth. The horizontal water permeability of lunar highland regolith simulant before freeze-thaw is 1.6 × 10−13 m2 at a packing fraction of 0.6. From the porosity-depth profile available from previous studies, we also obtained the water permeability-depth curve, representing the vertical water permeabilities of 6 × 10−13–2 × 10−12 m2 and 7 × 10−14–3 × 10−13 m2 at the lunar surface and the depth of 5 m within the surficial lunar regolith layer, respectively. We also found that the water permeability of lunar highland regolith increased after one freeze-thaw cycle, achieving 6.4 times higher than the permeability before the freeze, and the increase was more significant with lower packing fractions. We suggest that the pore water in the solid phase due to the freeze encourages the rearrangement of the regolith particles changing the total contact area between the particles. This study will help us better understand the abundance and distribution of molecular water on the lunar surface, lunar surface processes, and regolith utilizations.

DOI： 10.1016/j.actaastro.2023.09.027

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.actaastro.2023.09.027.

記述言語：英語   出版者・発行元：Elsevier  

The calcium carbonate (CaCO_3) scale generated in water pipes and heat exchangers causes serious problems such as pipe blockage and corrosion. This study investigates the effect of the 4-to-10 μm-long and 350-to-700 nm centering-nucleus-wide ZnO tetrapod-like nanomaterials and polydimethylsiloxane composite (t-ZnO/PDMS) on deposition and polymorphism of CaCO_3 crystals on the stainless-steel substrate. The results showed that the t-ZnO/PDMS coating inhibited CaCO_3 depositions and represented an excellent antifouling coating. The weight-based inhibition efficiencies of CaCO_3 deposition were up to 81.3% and 63.2% at 20 °C and 60 °C, respectively. The t-ZnO/PDMS coating also exhibited good inhibition in the presence of liquid flow. The inhibition is primarily because the very fine concave-convex microstructure of the t-ZnO/PDMS coated surface lowered the surface energy of the substrates, making it difficult for CaCO_3 crystals to adhere to the surface. Also, metastable vaterite and aragonite precipitations were dominant in the t-ZnO/PDMS coated coupons at 20 °C and 60 °C, respectively, whereas the uncoated coupon exhibited calcite as the predominant polymorph in all the studied conditions. The t-ZnO/PDMS composite subject to the liquid flow made calcites distorted and framboidal vaterite aggregates, likely due to their mechanical effects. The inhibition of CaCO_3 depositions is due to achieving hydrophobicity on substrate surfaces, changing preferential polymorph formation, and tailoring the morphology of the given polymorph by the t-ZnO/PDMS composite.

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Results in Surfaces and Interfaces  

The calcium carbonate (CaCO3) scale generated in water pipes and heat exchangers causes serious problems such as pipe blockage and corrosion. This study investigates the effect of the 4-to-10 μm-long and 350-to-700 nm centering-nucleus-wide ZnO tetrapod-like nanomaterials and polydimethylsiloxane composite (t-ZnO/PDMS) on deposition and polymorphism of CaCO3 crystals on the stainless-steel substrate. The results showed that the t-ZnO/PDMS coating inhibited CaCO3 depositions and represented an excellent antifouling coating. The weight-based inhibition efficiencies of CaCO3 deposition were up to 81.3% and 63.2% at 20 °C and 60 °C, respectively. The t-ZnO/PDMS coating also exhibited good inhibition in the presence of liquid flow. The inhibition is primarily because the very fine concave-convex microstructure of the t-ZnO/PDMS coated surface lowered the surface energy of the substrates, making it difficult for CaCO3 crystals to adhere to the surface. Also, metastable vaterite and aragonite precipitations were dominant in the t-ZnO/PDMS coated coupons at 20 °C and 60 °C, respectively, whereas the uncoated coupon exhibited calcite as the predominant polymorph in all the studied conditions. The t-ZnO/PDMS composite subject to the liquid flow made calcites distorted and framboidal vaterite aggregates, likely due to their mechanical effects. The inhibition of CaCO3 depositions is due to achieving hydrophobicity on substrate surfaces, changing preferential polymorph formation, and tailoring the morphology of the given polymorph by the t-ZnO/PDMS composite.

DOI： 10.1016/j.rsurfi.2023.100138

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Tectonophysics  

The analogue materials play a critical role in dynamically scaled experiments, defining the processes that can be simulated and the structures observable in the model. The dynamic scaling enables the direct comparison between the model and its natural counterpart. To obtain such a model the physical and mechanical properties of the analogue material must be scaled with respect to the rock prototype. A large variety of materials have been applied in analogue modelling studies to address the physical and mechanical requirements for the simulation of (i) upper crust, (ii) middle crust and (iii) lower crust and mantle processes. Nevertheless, the development of new model materials represents a continuous improvement of the analogue modelling techniques. We investigated the mechanical and physical properties of a new Granular Rock-Analogue Material (GRAM) (introduced in Massaro et al. (2022)) and its component materials. GRAM is an ultra-weak artificial sandstone composed of quartz sand cemented with gypsum, capable to deform by tensile and shear failure under variable stress conditions. GRAM aggregates in different mixing ratios (from 1% to 4% in weight of hemihydrate powder) were systematically tested with ring-shear tests and uniaxial compression tests. The relationships between the hemihydrate content and the mechanical properties of GRAM were examined. Additionally, the sample preparation procedure of GRAM was investigated, evaluating the impact of the residual water content on the mechanical properties of GRAM aggregates and defining a standard preparation procedure. Finally, GRAM was compared to natural rocks and to other granular materials applied in analogue modelling studies, in terms of physical and mechanical properties, application to physical modelling and dynamic scaling. It was underlined how the application of GRAM aggregates in dynamically scaled experiments can enhance the comprehension of the fault and fracture processes occurring at the scale of the damage zone.

DOI： 10.1016/j.tecto.2023.229828

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2023CN000210

記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

<p>立山黒部ジオパーク（以後，立黒）は，『高低差4000 mロマン　富山の中の地球へ行こう』をテーマにした，富山県東部の9市町村にまたがるジオパークである．日本海から北アルプスまで，43のジオサイト，40の文化サイト，28の自然サイトを有しているが，地形的特徴からジオサイトがなかなか見学に行けない山岳地帯に多い感は否めない．そのため市街地から近く，児童生徒の学習にも使え，手軽に見学できるジオサイトの開拓が望まれていた．　今回，富山県中新川郡立山町の中心部から車で15分程の稲村にある産廃場跡地を整備したところ，スランプ構造の全容が観察できる大露頭（南北約80 m，東西約70 m，高さ約30 mの範囲に内向き斜面の崖が「凡」字形に配列している）が出現し，それを一般公開することができた．ここに至るまでの主な経緯は，2000年頃：最初の地権者により採土場として掘削を開始．’05年：新上市町誌（新上市町誌編集委員会編，2005）に「折戸凝灰岩層，海底火山灰の堆積した緑色凝灰岩の地層」として，スランプ構造の写真が掲載される．’05－’10年？：現地権者が瓦の粉砕施設をつくり，稼働するも程なく中止．産廃場に使うがこれも中止．以後，遊休地．’21年2月：立黒のジオパーク再認定決定．審査員から身近なジオサイトの開発を望まれる．5月：立黒研究教育部会で予備調査を行い，巨大なスランプ構造が灌木と崖錐堆積物にかなり被覆されているものの，ジオサイトになりうると判断．6月：地権者に立ち入りの許可を得ると同時に，町役場にジオサイト化に向けて協力を要請．11月：役場担当から，露頭の学術的評価が欲しいとの要請で，立黒が保柳に現地調査を依頼．保柳から情報を得た荒戸，立黒学術顧問竹内章富山大学名誉教授も加わり現地調査．地元紙が露頭を写真入りで報道．’22年1月：荒戸がボーリングコア採取の許可を得たい旨．地権者との交渉をジオパークに依頼．同時に，荒戸が代表を務める『海底地すべりモデルの構築：日高沖「静内海底地すべり堆積体」の発生機構と運動様式』（科研費番号 19H02397）の研究チームに，当該露頭の調査研究を提案．立黒が地権者にボーリングコア採取を説明．許可を得る．4月：勉強会を実施し，崖錐堆積物を取り除けば，スランプの構造を立体的に研究できる大露頭が出現する可能性が議論される．5月：町民向け現地説明会の実施と地元紙，ケーブルテレビの報道．6月：現地調査を実施し，重機を使って整備工事を行い，研究を進めることを確認．これを受けて，立黒が地権者に調査方法を説明，実施の承諾を得る．7月：町役場に露頭整備にあたる業者の紹介を依頼し，それに基づき見積もりを徴取．8月：露頭の整備，調査，整備後の立黒の利用に関して，地権者，荒戸が所属する秋田大学，立黒で覚書を締結．9月：整備工事開始し，十日程で終了．その後，予備調査．ステップ設置，底面のトレンチの工事を追加で依頼．10月：チームでの調査．地元小学5・6年生全員が見学．11月：チームでの調査．分析用試料の採取．説明看板の内容の検討を開始．下旬にステップの撤去とトレンチの埋め戻し．12月：ワークショップの開催．解説看板の土台の設置．’23年4月：解説看板，安全ポールコーンの設置．同時に立入禁止の柵を撤去し，一般公開の開始．5月：立黒ジオガイド向け現地研修会の開催．調査は継続中．　露頭の調査開始から一般公開まで極めて順調であったは要因は，・科研費の一部を露頭整備に使用し，そのまま見学対象となった．・地権者との交渉や町役場と現場周辺住民への説明，調査前後の整備及び撤収作業の立ち合いは立黒が担当．・露頭が県道のすぐ脇にあり，駐車スペースも十分で，大型重機による作業が可能．・露頭整備を請け負った業者が現場から車で15分の距離で，高所作業車，発電機，排水ポンプ，高圧洗浄機など急な要望にも対応．・地権者との覚書の締結で，現場の大規模な改変が可能となる．　一方，残る問題点は，・すでに泥岩部が剥離し始めており，何もしなければ10数年で整備前の状態に戻ると思われるが，保全する費用の目処が立っていない．・以前の施設の残骸を撤去しきれていない．　ジオサイトにはその保全が求められるので，この露頭をジオサイトとして維持するためには，上記問題点の解消が必要である．謝辞：同地での調査と一般公開を快諾くださった英修興産有限会社と，調査作業諸事にご協力頂いた有限会社きんたに心より感謝申し上げます．文献：新上市町誌編集委員会編，2005，新上市町誌．上市町，921p．</p>

DOI： 10.14863/geosocabst.2023.0_47

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

<p>地質現象は、一般に規模や時間が人間にとって直感的に理解できる範囲を超えている。それを補うために、実験や数値シミュレーションを用いてスケールを変更する試みが行われてきた。中でも褶曲や断層などの変形に関する分野では、時間的にもサイズ的にも現象を縮小して再現することで、最終的な変形形態やその形成過程について理解するだけではなく、その知見を地下資源開発の探査と開発に役立ててきた。褶曲形成に関する理論化がほぼ完成され、それを解析する能力が十分に向上した1980年代には、褶曲変形に関する検討は数値シミュレーションで十分に行えるようになった。一方断層などの破壊に関する検討は、数値シミュレーションの制約が大きいことから主として物理実験によって検討が進められてきた。物理実験によって変形現象を縮小再現する際、現象の物理的な意味を保ったまま（つまり物理的等価に）縮小するための理論的な条件（相似則）は1950年代に完成していたが、その条件を満たすように実験を行うことは困難であった。しかし、2000年以降に微小物性を計測できる試験機が開発されたことに伴い、相似律を満たすように実験材料の物性を微調整することができるようになった。これを受けて、様々な地質環境における変形構造を物理的等価に縮小・再現する物理実験が可能となってきている。本講演では、Massaro et al 2021, Massaro et al 2023の成果を基に、縮小模型実験の可能性が広がりつつある状況を報告する。 Massaro, L., Adam, J., Yamada, Y. 2023. Tectonophysics 855, 229828. Massaro, L., Adam, J., Jonade, E., Yamada, Y. 2021. Geological Magazine. 1-24.</p>

DOI： 10.14863/geosocabst.2023.0_246

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

<p><b>１．はじめに</b>　発表者らは海底地すべりの発生メカニズムを堆積学的に理解し運動学的なモデルを構築することを目的に研究を進めている^{[1, 2, 3]}．この過程で，一般的な地質調査に加えて三次元デジタル露頭モデル等を活用した地質解析を実施し，地すべり堆積体の多様で複雑な内部変形構造と滑動様式を検討したので，その概要を報告する．<b>２．手法</b><b>(1) 準備作業：</b>富山県上市町稲村露頭の調査に先立ち，作業員および重機を導入して，灌木や下草類の伐採と露頭前面下部の崖錐被覆堆積物の除去を実施した．<b>(2) 地質調査：</b>露頭下部の地表付近については，一般的な岩相層序調査ならびに堆積相解析を実施した。詳細な堆積構造および変形構造を観察するため，グラインダー等を用いて一部露頭面の研磨を行なった．露頭高所については高所作業車を用いて近接し，岩相層序および堆積相の解析を行なった．<b>(3) 空中写真撮影：</b>ドローンを用いて，鉛直上空からのシリーズ画像および各露頭面に直角の斜めシリーズ画像をオーバーラップ率が85％以上になるように撮影した．<b>(4) 三次元テクスチャーモデル製作と解釈への活用：</b>ドローン空撮のシリーズ画像を三次元モデリングソフトウェア「pix4Dmapper」に取り込んで三次元デジタル露頭モデルを製作し，これを用いてより確度の高い地層対比や構造解釈を行なった．<b>３．結果</b><b>(1) 層序・岩相・地質構造：</b>稲村露頭に分布する地層は，下部中新統福平層折戸凝灰岩部層の凝灰岩，凝灰角礫岩および凝灰質砂岩泥岩互層である^[4]．互層中の泥岩にはまれに大型植物の葉片化石が含まれるが，年代決定に資する微化石あるいは大型化石は検出されていない．分布する地層は，岩相の特徴に基づき，下位からA～Gの7ユニット（A, E〜G：凝灰岩および凝灰角礫岩，B〜D：凝灰質砂岩泥岩互層）に区分される．互層中の泥岩層には，大小の生痕化石が認められる．露頭の範囲全体としては約25度の北傾斜で，大局的には安定した地質構造をもつ．<b>(2) ユニットDの変形様式：</b>同層は内部に顕著なスランプや撓曲，低角逆断層などの変形構造を有し，概ね10〜15m程度の層厚を有する．これらの変形構造は，層内の逆断層を境にした北側のみで観察され，逆断層の南側では下位のユニットB, Cと調和的で安定した走向傾斜をもつ．内部変形構造の観察されないユニットDの層厚は約5mである．<b>(3) ユニットDの鍵層追跡：</b>同層の互層は，堆積学的特徴の異なる8層（便宜的に下位からD1〜8と仮称）の凝灰質砂岩鍵層と挟材する凝灰質泥岩層の繰り返しからなる．凝灰質砂岩層の層厚はそれぞれ15〜55cm程度で，基底部の極粗粒から細粒へ上方細粒化し凝灰質泥岩層へ漸移する．凝灰質泥岩層は，見かけ上，10〜55cm程度の層厚をもつ．露頭北部の同層は，南方向への滑動により布団を畳むように折り曲げられ，褶曲軸面付近に形成される低角逆断層によって上盤側が下流へ変位して，8層全体ないしその一部，ならびに逆転した一部が繰り返すことによって層厚を増している．<b>(4) 地すべりの滑動モデル：</b>以上の特徴から，これらの変形構造はユニットD堆積後の早い時期に北方から南方へ向かう当時の斜面下方へ同層が滑動し，層内の逆断層を先端としてそれより上流側が滑動方向に短縮したことによって形成されたものと解釈される．それらの変形が形成される過程は，1) ユニットDはある場所から上流側が基底面を境として滑動し，滑動しないユニットDに乗り上げる, 2) その過程で横臥褶曲を作るが，3) 活動による短縮量が褶曲で解消しきれなくなるとすべり面が上位へ分岐しさらに乗り上げていく，4) こうした変形がオーバーステップ状に上流側へ波及することでユニットD, Eの変形が累積し成長する，と解釈される．<b>４．まとめ</b>　稲村露頭では，地質時代の水中地すべり堆積体の可視的な最小単位の変形構造を観察することができた．これらの空間的な位置および姿勢を詳細に記載するとともに，すべり面，低角逆断層面の物性を観察することで，その運動学的モデルを導出することができる．<b>謝辞：</b>英修興産有限会社，立山黒部ジオパーク協会の諸氏，有限会社きんた，鉄建建設株式会社に心より感謝する．なお，当該研究には日本学術振興会科学研究費（19H02397）の一部を使用した．<b>文献：[1]</b> 荒戸, 2018, 地質学会講演要旨, 110., <b>[2]</b> 荒戸, 2022, 石技誌, 87, 136-146., <b>[3]</b> 荒戸ほか, 2023, 堆積学会講演要旨, 9-10., <b>[4]</b> 金子, 2001, 地質雑, 107, 729-748.</p>

DOI： 10.14863/geosocabst.2023.0_353

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Tectonophysics  

Undulating topography on a subducting oceanic plate causes substantial deformation of the accretionary wedge. In particular, the subduction of a seamount is considered to induce 1) the development of landward concave topography such as reentrant and indented features, 2) compression within the accretionary wedge, and 3) disturbance of the primary thrust-sheet structures by uplift associated with the formation of multiple faults. However, according to previous seismic profiles, some subducting seamounts have provided suggestive evidence for weak wedge deformation rather than strong compression and uplift that were indicated in the previous model experiments. As the cross-sectional shape of an accretionary wedge is known to be strongly constrained by the internal and basal friction of the wedge, this study evaluates the effect of the frictional conditions of a subducting seamount on the deformation of the upper plate using analog experiments of two seamount models with low and high friction, respectively. Results show that subduction of a high-friction seamount causes continuous compression and uplift of the accretionary wedge, with the plate boundary fault zone composed of discontinuous multiple faults that offset vertically and partially overlapped to form a thick deformation zone. In contrast, a low-friction seamount is associated with a relatively thin wedge and a single plate boundary fault, which results in less compression compared with a high-friction seamount. During the subduction of a low-friction seamount, the accretionary wedge grows locally as the thickness of sediment on the seamount decreases, which has not been reported in previous studies. The wedge deformation pattern around the subducting Bennett Knoll Seamount in the Hikurangi Margin could be explained by the mechanism observed in the low-friction seamount subduction. From these results, we conclude that the frictional conditions on the seamount surface are a dominant control on the process of wedge deformation during the early stages of seamount subduction.

DOI： 10.1016/j.tecto.2022.229644

Web of Science

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Copernicus GmbH  

Abstract. The Oman Drilling Project (OmanDP), performed under theInternational Continental Scientific Drilling Program (ICDP), is aninternational scientific research project that undertook drilling at a range of sites in the Semail ophiolite (Oman) to collect core samples spanning the stratigraphy of the ophiolite, from the upper oceanic crust down to the basal thrust. The cores were logged to International Ocean Discovery Program (IODP) standards aboard the D/V Chikyu. During ChikyuOman2018 Leg 3 (July–August 2018), participants described cores from the crust–mantle transition (CM) sites. The main rock types recovered at these sites weregabbros, dunites and harzburgites, rocks typically forming the base of theoceanic crust and the shallow mantle beneath present-day spreading centres.In addition to the core description, selected samples were analysed by X-ray fluorescence spectrometry (XRF) for their chemical compositions, including major, minor and some trace elements. To complement these standard procedures, we developed newapproaches to measure ultra-trace element concentrations using a procedureadapted from previous works to prepare fine-grained pressed powder pelletscoupled with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis using instrumentation aboard the D/V Chikyu. First, three (ultra)mafic reference materials were investigated to test and validate our procedure (BHVO-2, BIR-1a and JP-1), and then the procedure was applied to a selection of gabbro and dunite samples from the CM cores toexplore the limitations of the method in its current stage of development.The obtained results are in good agreement with preferred values for thereference materials and with subsequent solution replicate analyses of the same samples performed in shore-based laboratories following Leg 3 for theCM samples. We describe this procedure for the determination of 37 minor and (ultra-)trace elements (transition elements and Ga, Li and Large-Ion Lithophile Elements (LILE), Rare Earth Elements (REE), High-Field-Strength Elements (HFSE), U, Th, and Pb) in mafic and ultramafic rocks. The presented method has the major advantage that it allows the determination at sea of the(ultra-)trace element concentrations in a “dry”, safe way, without usingacid reagents. Our new approach could be extended for other elements ofinterest and/or be improved to be adapted to other rock materials duringfuture ocean drilling operations aboard the D/V Chikyu and other platforms.

DOI： 10.5194/sd-30-75-2022

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記述言語：日本語   出版者・発行元：一般社団法人 日本地質学会  

<p>プレートの沈み込み帯に形成される付加体ウェッジは，多数のせん断帯が形成されることが特徴である．せん断帯はウェッジの変形様式や流体の流れを制御しており，その形成機構は極めて重要である．砂箱実験による先行研究では，典型的なウェッジの形状とせん断帯のパターンが報告されている．本研究では，充てん方法や材質を変え初生的な強度構造が異なる砂層を用意し，変形様式のバリエーションについて検討した．付加体ウェッジは，底面シートを敷いたアクリル製の箱（118 mm×693 mm×158 mm）に乾燥砂（厚さ約16 mm）を充てんし，シートを箱から引き出して砂層を変形させて作った．シートの水平変位は250 mmとした．実験に用いた砂層は，(A)空中落下で充てんした豊浦珪砂層，(B)流し込みで充てんした豊浦珪砂層，(C)空中落下充てんのマイクロビーズ下層＋空中落下充てんの豊浦珪砂上層，(D)空中落下充てんのマイクロビーズ下層＋流し込み充てんの豊浦珪砂上層，の4種類である．それぞれの砂層についてX線コンピュータトモグラフィー（XCT）データをもとに強度構造を求めた．各実験における変形は連続写真で記録し，一部の実験ではXCTスキャンを行った． 実験の結果，付加体ウェッジの表面傾斜角は実験Aで最も大きくなり，実験B，C，D の順に傾斜角が小さくなった．また，実験Bでは実験Aよりもせん断帯の間隔が狭くなったが，これは流し込んだ砂層のひずみ弱化の程度が小さいためであると考えられる．実験CおよびDでは，バックスラストが明瞭に発達し，底面のマイクロビーズ層がデコルマとして変位した．CT画像からは，実験Aでは新たなせん断帯 （フロンタルスラスト）が形成される直前にデコルマの伝播が短期間で起こり，実験CやDでは新たなフロンタルスラストが形成されるかなり以前からデコルマの伝播が始まっている様子が見られた．これらの結果は，初生的な強度構造が付加体ウェッジのせん断帯間隔とデコルマの伝播様式に影響を与えることを示している． また，Cascadia，南海トラフ，Barbadosなどの現世の天然付加体ウェッジにおいても，実験で観察されたような構造の特徴が観察される．これらのウェッジの検層データと反射法地震探査データを比較すると，インプット堆積層の密度構造に違いがあること，ウェッジ部ではプロトデコルマの有無やバックスラストの発達具合に違いがあることがわかる．このことは，インプット堆積層の強度特性が天然の付加体ウェッジの変形様式にも影響を及ぼしている可能性を示唆している．</p>

DOI： 10.14863/geosocabst.2022.0_361

CiNii Research

掲載種別：研究論文（学術雑誌）  

Completely carbonated peridotites represent a window to study reactions of carbon-rich fluids with mantle rocks. Here, we present details on the carbonation history of listvenites close to the basal thrust in the Samail ophiolite. We use samples from Oman Drilling Project Hole BT1B, which provides a continuous record of lithologic transitions, as well as outcrop samples from listvenites, metasediments, and metamafics below the basal thrust of the ophiolite. 87Sr/86Sr of listvenites and serpentinites, ranging from 0.7090 to 0.7145, are significantly more radiogenic than mantle values, Cretaceous seawater, and other peridotite hosted carbonates in Oman. The Hawasina sediments that underlie the ophiolite, on the other hand, show higher 87Sr/86Sr values of up to 0.7241. δ13C values of total carbon in the listvenites and serpentinites range from −10.6‰ to 1.92‰. We also identified a small organic carbon component with δ13C as low as −27‰. Based on these results, we propose that during subduction at temperatures above >400°C, carbon-rich fluids derived from decarbonation of the underlying sediments migrated updip and generated the radiogenic 87Sr/86Sr signature and the fractionated δ13C values of the serpentinites and listvenites in core BT1B.

DOI： 10.1029/2021JB022704

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:title>Abstract</jats:title><jats:p>Seafloor massive sulphide (SMS) deposits, modern analogues of volcanogenic massive sulphide (VMS) deposits on land, represent future resources of base and precious metals. Studies of VMS deposits have proposed two emplacement mechanisms for SMS deposits: exhalative deposition on the seafloor and mineral and void space replacement beneath the seafloor. The details of the latter mechanism are poorly characterised in detail, despite its potentially significant role in global metal cycling throughout Earth’s history, because in-situ studies require costly drilling campaigns to sample SMS deposits. Here, we interpret petrographic, geochemical and geophysical data from drill holes in a modern SMS deposit and demonstrate that it formed via subseafloor replacement of pumice. Samples from the sulphide body and overlying sediment at the Hakurei Site, Izena Hole, middle Okinawa Trough indicate that sulphides initially formed as aggregates of framboidal pyrite and matured into colloform and euhedral pyrite, which were replaced by chalcopyrite, sphalerite and galena. The initial framboidal pyrite is closely associated with altered material derived from pumice, and alternating layers of pumiceous and hemipelagic sediments functioned as a factory of sulphide mineralisation. We infer that anhydrite-rich layers within the hemipelagic sediment forced hydrothermal fluids to flow laterally, controlling precipitation of a sulphide body extending hundreds of meters.</jats:p>

DOI： 10.1038/s41598-021-87050-z

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

The understanding of formation properties in the mantle is relatively frontier subject in the geosciences research. To achieve the mantle sampling in the near future, Oman Drilling Project was carried out as a part of the International Continental scientific Drilling Program (ICDP) from 2017 to 2018, and both drilling and full coring operation were conducted at the former mantle-crust boundary (now exposed). Full suite of wireline log data was acquired with good quality in the drilling well and excellent quality core samples were continuously taken in the coring borehole nearby. To obtain the continuous geochemical composition of formation, the advanced pulsed neutron spectroscopy well logging was conducted first ever in scientific drilling project. The closure model, specific to igneous rocks, was applied for the spectroscopy log data processing and the result was quantitatively validated with X-ray fluorescence (XRF) measurements of the core samples with the complex mineralogy of ultramafic igneous rock, such as Oman Ophiolites. Then a mineralogical quantitative interpretation was carried out with the dry weight fraction of formation elements, and the results agreed with the core lithological description. This study confirmed that pulsed neutron spectroscopic measurements were key alternatives for continuous mineralogical quantification of igneous rocks, even without core samples, in the future mantle drilling project.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:p>Abstract. For more than half a century, exploring a complete sequence of the oceanic
crust from the seafloor through the Mohorovičić discontinuity (Moho)
and into the uppermost mantle has been one of the most challenging missions
of scientific ocean drilling. Such a scientific and technological
achievement would provide humankind with profound insights into the largest
realm of our planet and expand our fundamental understanding of Earth's deep
interior and its geodynamic behavior. The formation of new oceanic crust at
mid-ocean ridges and its subsequent aging over millions of years, leading to
subduction, arc volcanism, and recycling of some components into the mantle,
comprise the dominant geological cycle of matter and energy on Earth.
Although previous scientific ocean drilling has cored some drill holes into
old (> 110 Ma) and young (< 20 Ma) ocean crust, our
sampling remains relatively shallow (< 2 km into intact crust) and
unrepresentative of average oceanic crust. To date, no hole penetrates more
than 100 m into intact average-aged oceanic crust that records the long-term
history of seawater–basalt exchange (60 to 90 Myr). In addition,
the nature, extent, and evolution of the deep subseafloor biosphere within
oceanic crust remains poorly unknown. To address these fundamentally
significant scientific issues, an international workshop “Exploring Deep
Oceanic Crust off Hawai`i” brought together 106 scientists and engineers
from 16 countries that represented the entire spectrum of disciplines, including
petrologists, geophysicists, geochemists, microbiologists, geodynamic
modelers, and drilling/logging engineers. The aim of the workshop was to
develop a full International Ocean Discovery Program (IODP) proposal to
drill a 2.5 km deep hole into
oceanic crust on the North Arch off Hawai`i with the drilling research vessel Chikyu. This drill hole would provide
samples down to cumulate gabbros of mature (∼ 80 Ma) oceanic
crust formed at a half spreading rate of ∼ 3.5 cm a−1. A Moho
reflection has been observed at ∼ 5.5 km below the seafloor at
this site, and the workshop concluded that the proposed 2.5 km deep
scientific drilling on the North Arch off Hawai`i would provide an essential
“pilot hole” to inform the design of future mantle drilling.
</jats:p>

DOI： 10.5194/sd-29-69-2021

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>
Seafloor hydrothermal deposits form when hydrothermal fluid mixes with ambient seawater, and constituent sulfide minerals are usually interpreted to precipitate abiogenically. Recent research drilling at Izena Hole and Iheya North Knoll in the middle Okinawa Trough (East China Sea), combined with secondary ion mass spectrometry determinations of δ34S in pyrite grains, provides compelling evidence that the initial stage of subseafloor sulfide mineralization is closely associated with microbial sulfate reduction. During the sulfide maturation process, pyrite textures progress from framboidal to colloform to euhedral. Pyrite δ34S has highly negative values (as low as –38.9‰) in framboidal pyrite, which systematically increase toward positive values in colloform and euhedral pyrite. Sulfur isotope fractionation between seawater sulfate (+21.2‰) and framboidal pyrite (–38.9‰) is as great as –60‰, which can be attained only by microbial sulfate reduction in an open system. Because framboidal pyrite is commonly replaced by chalcopyrite, galena, and sphalerite, framboidal pyrite appears to function as the starting material (nucleus) of other sulfide minerals. We conclude that framboidal pyrite, containing microbially reduced sulfur, plays an important role at the initial stage of subseafloor sulfide mineralization.

DOI： 10.1130/g47943.1

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:p>Microorganisms in marine subsurface sediments substantially contribute to global biomass. Sediments warmer than 40°C account for roughly half the marine sediment volume, but the processes mediated by microbial populations in these hard-to-access environments are poorly understood. We investigated microbial life in up to 1.2-kilometer-deep and up to 120°C hot sediments in the Nankai Trough subduction zone. Above 45°C, concentrations of vegetative cells drop two orders of magnitude and endospores become more than 6000 times more abundant than vegetative cells. Methane is biologically produced and oxidized until sediments reach 80° to 85°C. In 100° to 120°C sediments, isotopic evidence and increased cell concentrations demonstrate the activity of acetate-degrading hyperthermophiles. Above 45°C, populated zones alternate with zones up to 192 meters thick where microbes were undetectable.</jats:p>

DOI： 10.1126/science.abd7934

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>To explore a local relationship between geological structures and the occurrence of very-low-frequency earthquakes (VLFEs), a particular class of slow earthquakes with characteristic periods of 10–100 s, we investigated three-dimensional (3D) structural features using reprocessed 3D seismic data from the Nankai Trough off Kumano, southwestern Japan. In this region, VLFEs have been observed along the subducting Philippine Sea Plate. Although the detailed source distribution of VLFEs was estimated by means of recent land-based and offshore seismic networks, the relation with geological features is not well understood. First, we reprocessed the 3D seismic data with advanced techniques and reinterpreted the fault distribution in the sediment layer of the accretionary prism and tracked two key horizons: a décollement and the oceanic crust surface. In the accretionary prism sediments, multiple continuous reflectors of basal detachments in the underthrust sequence and conjugate faults cutting the shallow imbricated thrust sequence were identified. In contrast to the gentle variation in the décollement surface, the topographic relief of the oceanic crust was prominent, with ridges and surface displacement due to faults in the oceanic crust. Then, we compared the structural features with the VLFE source locations. Most VLFEs were located deep in the underthrust sediments where the sediments may consist of underconsolidated muds. Furthermore, a high spatial correlation was observed between the VLFE distribution and the oceanic crust topographic relief. The maximum stress direction, which was inferred from the conjugate faults in the imbricated thrust zone, was consistent with the spatial relation between the VLFE localization and the oceanic crust central ridge. Oceanic crust ridges may cause strain accumulation in the underthrust sediments on the landward sides of the ridges, and low-angle slow thrust movements might be caused using weak slip planes in the underthrust muddy sediments. That is, the topographic relief of the oceanic crust may control the occurrence of shallow VLFEs in the Nankai Trough.

DOI： 10.1186/s40623-020-01204-3

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jhydrol.2020.125152

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>
Sandy trench-fill sediments at accretionary margins are commonly scraped off at the frontal wedge and rarely subducted to the depth of high-pressure (HP) metamorphism. However, some ancient exhumed accretionary complexes are associated with high-pressure–low-temperature (HP-LT) metamorphic rocks, such as psammitic schists, which are derived from sandy trench-fill sediments. This study used sandbox analogue experiments to investigate the role of seafloor topography in the transport of trench-fill sediments to depth during subduction. We conducted two different types of experiments, with or without a rigid topographic high (representing a seamount). We used an undeformable backstop that was unfixed to the side wall of the apparatus to allow a seamount to be subducted beneath the overriding plate. In experiments without a seamount, progressive thickening of the accretionary wedge pushed the backstop down, leading to a stepping down of the décollement, narrowing of the subduction channel, and underplating of the wedge with subducting sediment. In contrast, in experiments with a topographic high, the subduction of the topographic high raised the backstop, leading to a stepping up of the décollement and widening of the subduction channel. These results suggest that the subduction of stiff topographic relief beneath an inflexible overriding plate might enable trench-fill sediments to be deeply subducted and to become the protoliths of HP-LT metamorphic rocks.

DOI： 10.1130/ges02212.1

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2019jb019060

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2019jb018877

記述言語：その他   掲載種別：研究論文（学術雑誌）  

Abstract. The Chikyu Shallow Core Program (SCORE) has been started to provide
more opportunities for the scientific ocean drilling of shallow boreholes
(up to 100 m) during a short-term expedition. The proposal flow is a
simplified version of that of the International Ocean Discovery Program (IODP).
Although there are several limitations for a SCORE project, the opportunity
to retrieve 100 m of continuous core samples will be of great interest for
the scientific ocean drilling community in multiple disciplines. The first
expedition of the SCORE program was implemented off Cape Erimo, Hokkaido,
northern Japan. The target of the drilling was to investigate the impact of
submarine mass transport on the subseafloor sedimentary biosphere. In the
preliminary observation of the core samples, including X-ray computed tomography (CT) scan image
analysis, chaotic and inclined beds were found and interpreted as mass
transport deposit (MTD) units.

DOI： 10.5194/sd-27-25-2020

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.2465/jmps.191008

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2019tc006033

記述言語：英語   掲載種別：研究論文（学術雑誌）  

<jats:p>Holes BA1B and BA3A were drilled into the Wadi Tayin Massif, southern ophiolite complex of Oman, a fragment of the Tethyan oceanic lithosphere obducted onto the Arabian continent. Within the sequence, we have studied a portion of the shallow mantle, composed mainly of strongly serpentinised harzburgite that embeds dunitic levels, the biggest being over 150 m thick. The formation of thick dunitic channels, already approached via published structural and mathematical models, is here investigated with a mineral chemistry approach. We focused on Cr-spinel, the only widespread phase preserved during serpentinization, whose TiO2 content displays a wide variability from low in harzburgite, (TiO2 < 0.25 wt. %), typical of non-metasomatised ophiolite mantle, to moderately high in dunite (TiO2 < 1.10 wt. %) characterizing a rock/melt interactions. The high variability of TiO2, accompanied by similar patterns of Cr# and Mg# is observed, in a fractal pattern, at all scales of investigation, from the whole channel scale to the single thin section, where it affects even single grain zonings. Our results suggest that the over 150 m thick dunite channel here investigated was formed by coalescence of different scale melt channels and reaction zones with different sizes, confirming the published structural model.</jats:p>

DOI： 10.3390/min10020167

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2019.104080

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.12.049

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/jpg.12744

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.08.017

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.06.021

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.11.014

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.06.014

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2019.05.023

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.12.050

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.05.033

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2018.06.010

記述言語：その他   掲載種別：研究論文（学術雑誌）  

Abstract. Imaging via pre-stack depth migration (PSDM) of reflection towed-streamer multichannel seismic (MCS) data at the scale of the whole crust is inherently difficult. This is because the depth penetration of the seismic wavefield is controlled, firstly, by the acquisition design, such as streamer length and air-gun source configuration, and secondly by the complexity of the crustal structure. Indeed, the limited length of the streamer makes the estimation of velocities from deep targets challenging due to the velocity–depth ambiguity. This problem is even more pronounced when processing 2-D seismic data due to the lack of multi-azimuthal coverage. Therefore, in order to broaden our knowledge about the deep crust using seismic methods, we present the development of specific imaging workflows that integrate different seismic data. Here we propose the combination of velocity model building using (i) first-arrival tomography (FAT) and full-waveform inversion (FWI) of wide-angle, long-offset data collected by stationary ocean-bottom seismometers (OBSs) and (ii) PSDM of short-spread towed-streamer MCS data for reflectivity imaging, with the former velocity model as a background model. We present an application of such a workflow to seismic data collected by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) in the eastern Nankai Trough (Tokai area) during the 2000–2001 Seize France Japan (SFJ) experiment. We show that the FWI model, although derived from OBS data, provides an acceptable background velocity field for the PSDM of the MCS data. From the initial PSDM, we refine the FWI background velocity model by minimizing the residual move-outs (RMOs) picked in the pre-stack-migrated volume through slope tomography (ST), from which we generate a better-focused migrated image. Such integration of different seismic datasets and leading-edge imaging techniques led to greatly improved imaging at different scales. That is, large to intermediate crustal units identified in the high-resolution FWI velocity model extensively complement the short-wavelength reflectivity inferred from the MCS data to better constrain the structural factors controlling the geodynamics of the Nankai Trough.

DOI： 10.5194/se-10-765-2019

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.3389/feart.2019.00117

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2018gc008173

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2018jb016799

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.5670/oceanog.2019.127

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/1365-2478.12724

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Detailed reconstruction of Indian summer monsoons is necessary to better understand the late Quaternary climate history of the Bay of Bengal and Indian peninsula. We established a chronostratigraphy for a sediment core from Hole 19B in the western Bay of Bengal, extending to approximately 80 kyr BP and examined major and trace element compositions and clay mineral components of the sediments. Higher delta O-18 values, lower TiO2 contents, and weaker weathering in the sediment source area during marine isotope stages (MIS) 2 and 4 compared to MIS 1, 3, and 5 are explained by increased Indian summer monsoonal precipitation and river discharge around the western Bay of Bengal. Clay mineral and chemical components indicate a felsic sediment source, suggesting the Precambrian gneissic complex of the eastern Indian peninsula as the dominant sediment source at this site since 80 kyr. Trace element ratios (Cr/Th, Th/Sc, Th/Co, La/Cr, and Eu/Eu*) indicate increased sediment contributions from mafic rocks during MIS 2 and 4. We interpret these results as reflecting the changing influences of the eastern and western branches of the Indian summer monsoon and a greater decrease in rainfall in the eastern and northeastern parts of the Indian peninsula than in the western part during MIS 2 and 4.

DOI： 10.1029/2018gc007772

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-018-20870-8

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1186/s40645-018-0228-z

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1186/s40645-018-0230-5

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>The National Gas Hydrate Program Expedition 02 was conducted in early 2015 using the Drilling Vessel <italic>Chikyu</italic> in the western part of the Bay of Bengal, India. During drilling off Vishakhapatnam, NE India, some bottom-simulating reflectors were penetrated, and numerous mass-transport deposits (MTDs) were identified. The recovered cores were composed of post-late Miocene muddy slope deposits containing the late Miocene–Pliocene hiatus that is widespread in that region. Based on detailed visual core descriptions and calcareous nannofossil biostratigraphy, two major MTD-rich intervals were identified: the Pleistocene interval above the hiatus, and the middle–late Miocene interval below it. Although the MTDs in both intervals are composed of variously coloured clay–silt blocks in an olive-black or olive-grey silty clay matrix (muddy MTDs), the Pleistocene MTDs consist of larger-sized blocks (mostly less than a few metres but with some >10 m) without clear shear fabrics, whereas the Miocene MTDs contain smaller blocks (<0.1 m) with asymmetrical shear fabrics. The muddy blocks are composed of older components (Pliocene–Cretaceous) compared with the depositional ages of the MTDs. The high abundance of MTDs above the hiatus and the depositional ages of the interbedded coherent layers indicate that large-scale MTDs occurred repeatedly during the Pleistocene. Such repeated MTDs contributed to maintaining the high sedimentation rate in this area and potentially provided stable pressure and temperature conditions for the formation of gas hydrates.

DOI： 10.1144/sp477.12

記述言語：日本語  

Submarine slides and marine geohazards: the study results so far and current problems

DOI： 10.5575/geosoc.2017.0031

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.tecto.2015.05.008

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jsg.2016.03.005

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/iar.12149

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.tecto.2015.12.023

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2016.03.006

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Microbial life inhabits deeply buried marine sediments, but the extent of this vast ecosystem remains poorly constrained. Here we provide evidence for the existence of microbial communities in similar to 40 degrees to 60 degrees C sediment associated with lignite coal beds at similar to 1.5 to 2.5 km below the seafloor in the Pacific Ocean off Japan. Microbial methanogenesis was indicated by the isotopic compositions of methane and carbon dioxide, biomarkers, cultivation data, and gas compositions. Concentrations of indigenous microbial cells below 1.5 km ranged from <10 to similar to 10(4) cells cm(-3). Peak concentrations occurred in lignite layers, where communities differed markedly from shallower subseafloor communities and instead resembled organotrophic communities in forest soils. This suggests that terrigenous sediments retain indigenous community members tens of millions of years after burial in the seabed.

DOI： 10.1126/science.aaa6882

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1186/s40623-014-0176-9

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.egypro.2014.11.525

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.egypro.2014.11.666

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ijggc.2014.08.016

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/iar.12064

記述言語：その他  

DOI： 10.1007/978-3-319-04996-0_83

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/2013gc005154

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.marpetgeo.2013.11.008

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1002/grl.50888

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

In order to estimate recent surface displacement in Bangkok, we applied persistent SAR interferometry using ALOS/PALSAR images acquired October 2007 to December 2010. Previously, land subsidence due to excessive ground water pumping has been reported in this region. However, we detected that ground surface has rebounded during 3 years of the observation period. This rebounded surface can be interpreted as the response on the ground water recovery to confined aquifer due to the decrease in ground water usage. Since the rebounded areas correspond to past ground subsidence areas inferred from differential SAR interferometry using JERS-1/SAR images, it can be inferred that ground water recovery has especially occurred at the preceding subsidence areas.

DOI： 10.1109/IGARSS.2013.6723672

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

Development of slope failures at thrust fault scarps in analogue models: application to submarine landslides

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Sandbox models commonly produce slope failures and mass-transport on the top free surface, which can be an analogue for submarine slides. We have been conducting shortening experiments to model accretionary wedges at subduction margins under several basement configurations of the subducting plate. Slope failures periodically occur when thrust faults reach the top surface of the models. These failures are triggered by steepening of slopes related to the displacement along the underlying thrusts. Internal stress field and physical property of materials may have little impact on the pattern and geometry of failures. Experiments with a topographic relief (e.g., horst) in the basement produce irregular distribution in time of thrusting. Long-lived thrusts, generally initiate at the foot of topographic highs, tend to form longer slopes with thick piles of failed sediments in the footwall. These suggest that anomalous amount of failed sediments in accretionary wedge regions can be used to assume topographic relief in the basement that affected the geometry of detachment. When subducted, such detachment geometries may not be easy to recognize with geophysical technique.

DOI： 10.1007/978-94-007-2162-3_31

記述言語：英語   掲載種別：研究論文（学術雑誌）  

A comparative study of fossil sliding masses and the results of analog experiments indicates the systematic accumulation of submarine sliding masses at subduction margins. An analysis of sliding masses in the Middle Miocene Hota accretionary complex, Central Japan, combined with the results of analog experiments that simulated an accretionary wedge, revealed two types of slope failures at the toe of the accretionary wedge or at the head of an out-of-sequence thrust: relatively small but frequently developed failures on the lower parts of the slope (Type I failures), and relatively large but less frequent failures that affect the entire slope (Type II failures). The Type I slides are precursors of the larger Type II failures. These successive failure processes are recorded in the Hota accretionary complex as the following depositional sequence: three thin conglomerate layers containing small clasts (type I failure deposits) are overlain by a thick slope-failure deposit containing larger clasts (type II). In such an environment, carbonate-cemented and brecciated sandstones, which contain web structures, generally form at depth and behave as competent layers during failure. Clasts of such sandstones are indicative of large slope failures and are found only in type II failure deposits. Type II failures affect the sediment to a depth of similar to 2-10 m, whereas type I failures are surficial (<1 m depth), as inferred from the results of analog experiments and field observations. This systematic pattern of slope failure is important in terms of understanding the formation mechanism of submarine slope failures and in predicting such failures.

DOI： 10.1007/978-94-007-2162-3_32

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/978-94-007-2162-3_1

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2010gc003365

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2010gc003417

記述言語：その他  

DOI： 10.1007/978-90-481-8885-7_9

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3720/japt.75.54

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2010gc003261

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1440-1738.2010.00731.x

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.tecto.2009.08.037

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.tecto.2009.09.007

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3720/japt.75.54

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

Numerical modeling of stress change related to fault activities in an accretionary wedge

記述言語：日本語  

DOI： 10.2208/jscejc.65.989

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1144/0016-76492008-136

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3124/segj.62.447

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1186/bf03353189

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

Experimental research of plagioclase (rock)-gas-water interaction at hydrothermal conditions for CO<inf>2</inf> mineralization
Experiments on CO2-water-rock interaction at hydrothermal conditions have been performed to investigate mineral dissolution and precipitatior phenomena, mainly focusing on calcite deposition from the alteration of plagioclase and rocks during CO2 sequestration into geothermal fields. Plagioclase from Shiga and granodiorite from the Ogachi hot/dry rock field (7 g
grain size is 0.5 to 2 mm) were independently enclosed with Kyoto tap water in a Teflon reaction container. The container is filled with CO2 (10 MPa) or N2 gas after evacuating and heated up to 150 °C in an electric furnace with rotation (1 rpm). After 1 to 15 days, the solutions were analyzed for their chemical compositions after filtration and the mineral surfaces were observed by using SEM-EDS. The concentration of Ca in the solutions reacted with CO2 quickly increases within 1 day and is + ∼50 mg/L higher than those without CO2 (with N2 gas). The saturation index shows that the solutions with CO2 are saturated with respect to carbonate such as calcite and aragonite during the reaction. Newly formed calcium carbonate (possibly calcite) was detected by SEM-EDS observation on the plagioclase surfaces, but the other minerals such as kaolinite were not. These results indicate that Ca can be released from rocks (silicates) easily and might be removed as CaCO3 during CO2 sequestration into relatively high temperature (geothermal) fields. Also, Ca-rich plagioclase has a high potential of CO2 fixation as carbonate.

DOI： 10.2465/gkk.38.111

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.egypro.2009.01.287

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3720/japt.74.12

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

Estimation of gas hydrate saturation with temperature calculated from hydrate threshold at C0002 during IODP NanTroSEIZE Stage 1 expeditions in the Nankai Trough

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

Estimation of strain accumulation around the Kumano Mega-Splay during IODP NanTroSEIZE Stage 1 expeditions in the Nankai Trough

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Submarine Landslides at Submarine Margins: Insights from Physical Models

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Integrated Ocean Drilling Program (IODP) Expedition 314 was a milestone, both as the inaugural scientific drilling mission of the new vessel, Chikyu, and as the first step in the multistage Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), an ambitious, coordinated, multiplatform, and multiexpedition drilling project designed to investigate fault mechanics and seismogenesis along subduction mega-thrusts through direct sampling, in situ measurements, and long-term monitoring. During Expedition 314, our primary goals were to obtain a comprehensive suite of geophysical logs and other downhole measurements at sites along a transect from the incoming plate to the Kumano forearc basin using state-of-the-art logging-while-drilling (LWD) technology. Drilling and logging was successfully completed at four sites, ranging in depth below the seafloor from 400 to 1400 m, with partial success at a fifth site. These sites included the frontal thrust and toe region of the outer accretionary prism near the trench, the fault zone and associated thrust sheet of a major out-of-sequence thrust system (the "megasplay" fault), 1 km thick forearc basin deposits, and highly deformed rocks of the interior of the accretionary prism. The principal goals of the LWD program were to document in situ physical properties
stratigraphie and structural features
sonic to seismic scale velocity data for core-log-seismic integration
and stress, pore pressure, and hydrological parameters through both scalar and imaging log measurements. All four sites are slated for continuous core sampling during subsequent IODP NanTroSEIZE expeditions. Depth objectives for this expedition ranged from ∼400 to 1400 meters below seafloor. Logging included the measurement of natural gamma radiation, azimuthal gamma ray density, neutron porosity, full waveform sonic velocity, azimuthal resistivity imaging, zero-offset vertical seismic profile, ultrasonic caliper, and annular fluid pressure, though not all logs in this suite were collected at all sites. Principal results of Expedition 314 include the following: 1. The megasplay thrust sheet is composed of highly deformed and fractured rocks that are anomalously well indurated relative to their present depth. 2. Present-day stress varies markedly along the NanTroSEIZE transect, and stresses in the upper 1.4 km are strongly compressional in the outer, active accretionary prism but extensional in the forearc basin. 3. The occurrence of gas hydrate as a cement preferentially located in sandy portions of turbidite beds above a bottom-simulating reflector was quantified. 4. Drilling at Sites C0001 and C0002 also provides important pilot hole information that will help prepare for the planned deep-riser sites for later stages of NanTroSEIZE drilling.

DOI： 10.2204/iodp.pr.314.2008

記述言語：その他   掲載種別：研究論文（学術雑誌）  

記述言語：その他  

Study of interaction between wedge deformation and friction change in decollemant zone by Distinct Element simulations

記述言語：その他   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（その他学術会議資料等）  

Estimation of permeability structure in an accretionary wedge by useing numerical simulation.

記述言語：その他  

Numerical simulation to estimate the influence of structural deformation to fluid flow in a modeled accretionary wedge

記述言語：英語   掲載種別：研究論文（学術雑誌）  

CO2 sequestration in a deep aquifer is considered one of the most effective method to solve Global warming. We must understand the behavior of injected CO2 to confirm long-term stability and economic efficiency of CO2 sequestration. We tried to monitor the behavior of gas, liquid and supercritical CO2 injected into water-saturated sandstone by measuring the resistivity of rock specimens. CO2 of gas, liquid, and supercritical phases was flushed through the sandstone specimens at three different flow rates. We could monitor the time-lapse behavior of CO2 in water-saturated sandstones. Also, we tried to convert the resistivity data to the CO2 saturation using Archie's equation. The saturations estimated from resistivity becomes nearly equal to the values calculated from actual outflow volumes. This result indicates the high reliability of electric exploration to monitor CO2 saturation. © 2005 Society of Exploration Geophysicists.

DOI： 10.1190/1.2369800

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>Active accretionary prisms at subduction margins generally include a horizontal detachment, décollement, within the sedimentary pile. The décollement, and its extension to undeformed regions (i.e., proto-décollement), corresponds to a layer of high fluid pressure. The deformation of the prisms, including such an anomalous layer, can be modelled and examined using analogue experiments and numerical simulations. Both these methods approximate the material under deformation as an assembly of particles (grains). The décollement layer is found to be best modelled by intercalating a layer with smaller internal frictional coefficient than the surrounding materials corresponding to the sediments. Our analogue experiments with dry sand and microglass beads reproduce structural geometry similar to that of interpreted seismic profiles at the toe of the prisms. Thrust faults originate from the horizontal beads layer and propagate upward with a constant angle of about 30°. Each of the fault bends produces a series of minor back thrusts. A particle image velocimetry (PIV) analysis revealed that the fault activity is characterized by intermittent reactivation and segmentation. The numerical simulations based on the distinct element method (DEM) were performed with similar kinematic settings and material properties as the analogue experiments. The numerical simulation results not only reproduce similar geometries as in the analogue experiments, but also show that the particle assembly experiences temporal variations in the deformation velocity and stress field as deformation propagates. This might be related to stick-slip motion of the frictional fault surfaces, which is a common feature of faulting during accretionary processes at subduction margins.

DOI： 10.1144/gsl.sp.2006.253.01.09

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>We report results of a study comparing numerical models of sandbox-type experiments. Two experimental designs were examined: (1) A brittle shortening experiment in which a thrust wedge is built in material of alternating frictional strength; and (2) an extension experiment in which a weak, basal viscous layer affects normal fault localization and propagation in overlying brittle materials. Eight different numerical codes, both commercial and academic, were tested against each other. Our results show that: (1) The overall evolution of all numerical codes is broadly similar. (2) Shortening is accommodated by in-sequence forward propagation of thrusts. The surface slope of the thrust wedge is within the stable field predicted by critical taper theory. (3) Details of thrust spacing, dip angle and number of thrusts vary between different codes for the shortening experiment. (4) Shear zones initiate at the velocity discontinuity in the extension experiment. The asymmetric evolution of the models is similar for all numerical codes. (5) Resolution affects strain localization and the number of shear zones that develop in strain-softening brittle material. (6) The variability between numerical codes is greater for the shortening than the extension experiment.

Comparison to equivalent analogue experiments shows that the overall dynamic evolution of the numerical and analogue models is similar, in spite of the difficulty of achieving an exact representation of the analogue conditions with a numerical model. We find that the degree of variability between individual numerical results is about the same as between individual analogue models. Differences among and between numerical and analogue results are found in predictions of location, spacing and dip angle of shear zones. Our results show that numerical models using different solution techniques can to first order successfully reproduce structures observed in analogue sandbox experiments. The comparisons serve to highlight robust features in tectonic modelling of thrust wedges and brittle-viscous extension.

DOI： 10.1144/gsl.sp.2006.253.01.02

記述言語：その他   掲載種別：研究論文（学術雑誌）  

<title>Abstract</title>We report a direct comparison of scaled analogue experiments to test the reproducibility of model results among ten different experimental modelling laboratories. We present results for two experiments: a brittle thrust wedge experiment and a brittleviscous extension experiment. The experimental set-up, the model construction technique, the viscous material and the base and wall properties were prescribed. However, each laboratory used its own frictional analogue material and experimental apparatus. Comparison of results for the shortening experiment highlights large differences in model evolution that may have resulted from (1) differences in boundary conditions (indenter or basal-pull models), (2) differences in model widths, (3) location of observation (for example, sidewall versus centre of model), (4) material properties, (5) base and sidewall frictional properties, and (6) differences in set-up technique of individual experimenters. Six laboratories carried out the shortening experiment with a mobile wall. The overall evolution of their models is broadly similar, with the development of a thrust wedge characterized by forward thrust propagation and by back thrusting. However, significant variations are observed in spacing between thrusts, their dip angles, number of forward thrusts and back thrusts, and surface slopes. The structural evolution of the brittle-viscious extension experiments is similar to a high degree. Faulting initiates in the brittle layers above the viscous layer in close vicinity to the basal velocity discontinuity. Measurements of fault dip angles and fault spacing vary among laboratories. Comparison of experimental results indicates an encouraging overall agreement in model evolution, but also highlights important variations in the geometry and evolution of the resulting structures that may be induced by differences in modelling materials, model dimensions, experimental set-ups and observation location.

DOI： 10.1144/gsl.sp.2006.253.01.01

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Regional stress has a significant impact on fault development during the formation of salt dome structures. To examine such effects of wrenching, we conducted a series of analog experiments of updoming using dry, granular materials and observed the deformation on the top free surface. The experiments included three deformation styles: (1) updoming followed by wrenching, (2) simultaneous updoming and wrenching, and (3) wrenching followed by updoming. In the first series of the experiments, the faults produced by simple updoming were overprinted by two strikeslip fault systems that were generated by the subsequent wrenching. The second series of experiments with the configuration of simultaneous updoming and wrenching generated normal faults in a direction perpendicular to relative extension by the wrench. In the third series of experiments, the Riedel and anti-Riedel shear faults formed by wrenching were deformed by the subsequent updoming and were overprinted by the faults related to the updoming. These experimental results are applied to the fault systems observed above dome structures in the United Arab Emirates region, where extensive faults in the northwest-southeast direction have developed. By analogy, these faults were probably formed during an updoming and simultaneous wrenching. The direction of simple shear inferred from a comparison of real faults and experimental results suggests that dextral wrenching caused by the Oman stress regime during the Late Cretaceous affected the region at the time of the updoming. Copyright © 2005 by The American Association of Petroleum Geologists.

DOI： 10.1306/1033718M852969

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2004gl021861

記述言語：その他   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.3124/segj.58.1

記述言語：その他   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1751-3928.2004.tb00183.x

記述言語：その他  

DOI： 10.1306/m82813c16

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/s0191-8141(02)00181-5

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/s0191-8141(02)00160-8

記述言語：その他   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/j.1747-5457.2002.tb00004.x

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Structural deformation (e.g. folds and faults) of geological strata has been analyzed by analog modeling techniques for nearly a century. Recent knowledge suggests that sandbox experiment is the most appropriate to model brittle behavior of the upper crust. This type of physical experiments using granular materials can also be done as numerical simulation (digital modeling) on the computer with the Discrete Element Method (DEM). Two types of geological settings, the extension case and the contraction case, are investigated and compared with the sandbox experiments results. It is concluded that the DEM approach to the geological deformation study can be a powerful tool to simulate fault related structures.

DOI： 10.1190/1.1816301

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Fault geometry is a primary control on hangingwall deformation. In this study, a series of inversion analogue experiments was conducted by using rigid fault surfaces of spoon-like true 3D geometries. The hangingwall geometry on serial sections of the experiments was then examined with conventional 2D geometric models. The deformation geometry of the hangingwall has an along-strike variation corresponding to the 3D geometry of the underlying detachment. The apparent shear plane inclination and the estimated shortening also show a systematic change along strike. These changes suggest that the hangingwall displacement had an along-strike element during deformation
the hangingwall material moves from the regions above salients to those above embayments in the detachment surface during contraction. The data presented in this paper help us understand 3D geometric relations between the hangingwall deformation and the underlying detachment surfaces.

DOI： 10.1190/1.1816712

開催年月日： 2023年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：富山市科学博物館   国名：日本国  

開催年月日： 2023年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京都大学   国名：日本国  

開催年月日： 2023年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京都大学   国名：日本国  

開催年月日： 2023年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京都大学   国名：日本国  

開催年月日： 2023年9月

記述言語：英語  

開催地：JOGMEC-TRC   国名：日本国  

開催年月日： 2023年9月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：日本財団   国名：日本国  

開催年月日： 2023年8月

記述言語：英語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：online (organized in Jakarta)   国名：インドネシア共和国  

開催年月日： 2023年7月

記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：GFZ, Potsdam, Germany   国名：ドイツ連邦共和国  

開催年月日： 2023年5月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：幕張メッセ   国名：日本国  

開催年月日： 2023年5月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：幕張メッセ   国名：日本国  

開催年月日： 2023年5月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：幕張メッセ   国名：日本国  

開催年月日： 2023年5月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：幕張メッセ   国名：日本国  

開催年月日： 2023年4月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：新潟大学   国名：日本国  

開催年月日： 2022年6月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：online   国名：日本国  

The understanding of formation properties in the mantle is relatively frontier subject in the geosciences research. To achieve the mantle sampling in the near future, Oman Drilling Project was carried out as a part of the International Continental scientific Drilling Program (ICDP) from 2017 to 2018, and both drilling and full coring operation were conducted at the former mantle-crust boundary (now exposed). Full suite of wireline log data was acquired with good quality in the drilling well and excellent quality core samples were continuously taken in the coring borehole nearby. To obtain the continuous geochemical composition of formation, the advanced pulsed neutron spectroscopy well logging was conducted first ever in scientific drilling project. The closure model, specific to igneous rocks, was applied for the spectroscopy log data processing and the result was quantitatively validated with X-ray fluorescence (XRF) measurements of the core samples with the complex mineralogy of ultramafic igneous rock, such as Oman Ophiolites. Then a mineralogical quantitative interpretation was carried out with the dry weight fraction of formation elements, and the results agreed with the core lithological description. This study confirmed that pulsed neutron spectroscopic measurements were key alternatives for continuous mineralogical quantification of igneous rocks, even without core samples, in the future mantle drilling project.

開催年月日： 2022年5月

記述言語：英語   会議種別：口頭発表（一般）  

国名：オーストリア共和国  

その他リンク： https://doi.org/10.5194/egusphere-egu22-10156

開催年月日： 2021年6月 - 2022年6月

記述言語：英語   会議種別：口頭発表（一般）  

国名：日本国  

記述言語：日本語  

S-2 Slope failure during accretionary process in geologic models

DOI： 10.14863/geosocabst.2007.0.2.0

記述言語：日本語  

帯水層におけるガスの挙動に関する実験的研究

記述言語：日本語  

炭酸ガスの地中貯留に伴うケーシングセメントと帽岩の劣化

種別：査読等 

外国語雑誌　査読論文数：3