著者
辻森 樹 石渡 明 坂野 昇平
出版者
一般社団法人 日本地質学会
雑誌
地質学雑誌 (ISSN:00167630)
巻号頁・発行日
vol.106, no.5, pp.353-362, 2000-05-15 (Released:2008-04-11)
参考文献数
35
被引用文献数
28 34

蓮華変成帯, 新潟県青海町上路(あげろ)地区湯ノ谷にエクロジャイト質藍閃石片岩が産する.この岩石は主として藍閃石(37%), ざくろ石(21%), オンファス輝石(19%), 緑れん石(19%)と少量の石英, 曹長石, フェンジャイト, 緑泥石, ルチル, チタン石から構成される.エクロジャイト相鉱物組み合わせ 'ざくろ石+オンファス輝石+藍閃石+緑れん石+石英+ルチル' はマトリクスの片理(S1)を構成し, わずかに二次的な緑泥石, 曹長石, 方解石に置換され, S1片理形成以前の緑れん石青色片岩相の鉱物組み合わせ '藍閃石+緑れん石+チタン石+石英+曹長石' の包有物列(S0)がざくろ石のコアに観察される.蓮華変成帯では, これまでにも残存エクロジャイト相鉱物の報告はあったが, 今回, 岩石組織と鉱物化学組成・累帯構造から, 初めて, 緑れん石青色片岩相からエクロジャイト相への累進変成作用を読みとることができた.
著者
辻森 樹
出版者
一般社団法人 日本鉱物科学会
雑誌
岩石鉱物科学 (ISSN:1345630X)
巻号頁・発行日
vol.51, no.1, pp.220310, 2022 (Released:2022-07-16)
参考文献数
110

This paper contains a series of essays which form a synopsis of my research career, which has been dedicated to orogenic and metamorphic processes in plate boundaries. It also presents my future research directions and latest investigations into simplifying the complexity of metamorphic rocks, their field observations, and associated convergent plate margin dynamics. Slab dehydration beneath forearcs and arc has been one of the most exciting problems in the field of convergent plate margin dynamics in recent decades. Orogenic and metamorphic processes are closely related. In the subduction zones, the fluid-mediated processes primarily control the crust-to-mantle transfer of volatiles, redox states of the wedge mantle peridotite and arc magmas, flux-melting to generate arc magmas, and seismicity. Although the methods of classical metamorphic petrology, based on phase equilibrium calculations, and the application of conventional geochronology continue to provide the opportunities to link high-pressure and ultra-high-pressure metamorphism to geophysical observations today, advances in geochemical techniques have great potential for key geological markers in global convergent margins. For example, recent analytical techniques and applications used in studies of metamorphic rocks, such as in-situ Li-B-Sr-Pb spot isotope analyses of jadeite, serpentinite, lawsonite, etc., evaluate hydration and dehydration along the subduction channels and subsequent slab-mantle interaction, and visualize more realistic ancient Pacific-type convergent margins. The scientific value of subduction-zone rocks and crustal rocks are not limited to their worth for geochemistry: Some metamorphic rocks and minerals are important for all realms of geological sciences, from nano-scale kinetics to the scale of mountain building events. Consequently, collaborative exchange among geoscientists, through the application of applying different approaches, tests, and challenges, to address problems related to plate boundaries in the future.
著者
辻森 樹 マルテンス ウヴェ
出版者
一般社団法人 日本地質学会
雑誌
地質学雑誌 (ISSN:00167630)
巻号頁・発行日
vol.112, no.2, pp.III-IV, 2006-02-15 (Released:2013-03-23)
参考文献数
2
被引用文献数
1
著者
辻森 樹 原 智美 進士 優朱輝 石坂 知裕 宮島 宏 木村 純一 青木 翔吾 青木 一勝
雑誌
日本地球惑星科学連合2019年大会
巻号頁・発行日
2019-03-14

Nunakawaite' (strontiojoaquinite) is an orthorhombic variety of strontiojoaquinite [Sr2Ba2(Na,Fe)2Ti2[Si4O12]2O2(O,OH)2·H2O]; it is a rare joaquinite group mineral that is only found in a riebeckite-bearing albitite in the serpentinite-matrix mélange of the Itoigawa–Omi area. The mineral was originally named after 'Princess Nunakawa' (nunakawa hime) in the Japanese Shinto mythology 'Kojiki'.'Nunakawaite' is characterized by remarkably high Ba, Zr, Nb, Zn, LREEs, MREEs, and enriched in U (35.8–721 µg·g-1), Pb (2.2–31 µg·g-1), and Th (7.42–2365 µg·g-1). LA-ICPMS analyses show highly variable U/Pb (238U/206Pb = 9.245–68.98) and Pb (207Pb/206Pb = 0.0758–0.756) isotope ratios, and the scattered trend define an isochron line with a lower intercept at 89.19 ± 1.07 Ma. The 'nunakawaite' U–Pb age confirms that the 'nunakawaite'-hosted riebeckite-bearing albitite formed at late Cretaceous. This implies that the serpentinite-matrix mélange unit with early Paleozoic jadeitites and late Paleozoic blueschist, eclogite and amphibolite was reactivated by a significantly younger tectonic event.In-situ Sr-Pb isotope analyses show two different isotope trends between Sr-rich accessory minerals in riebeckite-bearing albitite ('nunakawaite' and ohmilite) and those in jadeitite (itoigawaite, stronalsite, vesvianite, Sr-rich epidote). The Sr-Pb isotopes also support the idea that the riebeckite-bearing albitite formed by a fluid-induced metasomatic event different from the jadeitite-forming metasomatism at early Paleozoic. The formation of riebeckite-bearing albitite at ~90 Ma is coeval with late Cretaceous granitic intrusion of the Omi area (youngest zircon U–Pb: 90.8 ± 1.1 Ma: Nagamori et al. 2018). The granitic intrusion might have acted an important role in the formation of 'nunakawaite'. In other words, reactivation of metasomatic mineralization in the Paleozoic serpentinite mélange is recorded in the Cretaceous riebeckite-bearing albitite.
著者
辻森 樹 仁科 克一 石渡 明 板谷 徹丸
出版者
一般社団法人 日本地質学会
雑誌
地質学雑誌 (ISSN:00167630)
巻号頁・発行日
vol.106, no.9, pp.646-649, 2000-09-15 (Released:2008-04-11)
参考文献数
27
被引用文献数
21 23

The Fuko Pass metacumulate is a tectonic block (4.5×1.5 km in size) within the Oeyama peridotite body in the Inner Zone of southwestern Japan. It was metamorphosed under the high-pressure and moderate-temperature condition to form a mineral assemblage hornblende+clinozoisite+kyanite+paragonite+albite+rutile. K-Ar ages were determined on hornblende separates from four epidote amphibolite samples, yielding 443-403 Ma. This suggests a Siluro-Ordovician subduction-related metamorphic event for the Fuko Pass metacumulate, which is distinct from the Late Paleozoic high-P/T type metamorphic events of the Renge metamorphic belt in the Inner Zone of southwestern Japan. The Fuko Pass metacumulate is correlated, in age, with the Early Paleozoic high-P/T type schists (445-402 Ma) of the Kurosegawa klippe in the Outer Zone.
著者
辻森 樹 石渡 明 坂野 昇平
出版者
日本地質学会
雑誌
地質學雜誌 (ISSN:00167630)
巻号頁・発行日
vol.106, no.5, pp.353-362, 2000-05-15
被引用文献数
7 34

蓮華変成帯, 新潟県青海町上路(あげろ)地区湯ノ谷にエクロジャイト質藍閃石片岩が産する.この岩石は主として藍閃石(37%), ざくろ石(21%), オンファス輝石(19%), 緑れん石(19%)と少量の石英, 曹長石, フェンジャイト, 緑泥石, ルチル, チタン石から構成される.エクロジャイト相鉱物組み合わせ 'ざくろ石+オンファス輝石+藍閃石+緑れん石+石英+ルチル' はマトリクスの片理(S_1)を構成し, わずかに二次的な緑泥石, 曹長石, 方解石に置換され, S_1片理形成以前の緑れん石青色片岩相の鉱物組み合わせ '藍閃石+緑れん石+チタン石+石英+曹長石' の包有物列(S_0)がざくろ石のコアに観察される.蓮華変成帯では, これまでにも残存エクロジャイト相鉱物の報告はあったが, 今回, 岩石組織と鉱物化学組成・累帯構造から, 初めて, 緑れん石青色片岩相からエクロジャイト相への累進変成作用を読みとることができた.