著者

Masaki ENAMI Aya NISHII Takashi MOURI Motohiro TSUBOI Yui KOUKETSU

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.201204, (Released:2021-05-20)

被引用文献数

1

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Olivine is a major mineral in ultramafic and mafic rocks. Due to the higher Mg/Fe partition coefficient of olivine than the coexisting phases, the occurrences of Mg–poorer olivine grains, especially with Mg#[= Mg/(Mg + Fe2+)] = 0.2–0.6, are rarely reported, and thus, their spectroscopic data are limited. Fe–rich olivine phenocrysts showing compositional zoning with Mg# = ~ 0.5 (core) and ~ 0.3 (rim) and microphenocrysts with Mg# = ~ 0.4 (core) and ~ 0.2 (rim) occur in basaltic trachyandesite of Miocene Shitara volcanic rocks in central Japan. These olivine grains were investigated by Raman spectroscopy. Combining our data with the published values, we have revised the equation for Mg#–Raman spectrum relationship proposed by Mouri and Enami (2008) as follows: Mg# = 0.005446ω 2 − 0.20259ω + 1.8442 (correlation coefficient r 2 = 0.984), where ω is the difference between the doublet peak positions (κ2 − κ1).

著者

間嶋 寛紀 赤井 純治 茅原 一也 中牟田 義博 松原 聡

出版者

Japan Association of Mineralogical Sciences

雑誌

日本鉱物学会年会講演要旨集

巻号頁・発行日

pp.138, 2003 (Released:2004-07-26)

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新潟県青海・糸魚川地域のヒスイ輝石岩中にはヒスイ輝石岩形成以降に形成された二次的な脈が多く存在し,ここからはSrを主成分とする鉱物が多く産したが,蓮華石もその一つである 蓮華石(rengeite)Sr4ZrTi4 (Si2O7) 2O8は新潟県西部,青海・糸魚川地域の蛇紋岩メランジ中に含まれるヒスイ輝石岩から発見された(Miyajima et al.,2001).蓮華石は単斜晶系に属し,格子定数はa=13.97(1),b=5.675(7),c=11.98(1)Åである. 今回新潟県青海町産白色ヒスイ輝石岩を調べている中で二次的な脈の中から蓮華石様鉱物を見出した。肉眼あるいは双眼実体顕微鏡下では淡灰色から暗青灰色の色を示し長さ1mm以下の脈状集合体または長さ0.2mm以下の短柱状自形結晶をなして産する.共生鉱物は脈を埋めて産するソーダ沸石と,初生的に形成されたジルコンである.ヒスイ輝石は0.5mm以下の自形から半自形で,しばしば脈状に著しい破砕を受けている.この蓮華石様鉱物の短柱状の形態はこの試料以外ではほとんど見られず,他の試料では蓮華石は放射針状の結晶集合体をなすことが多い.本試料は偏光顕微鏡下では濃青色から淡褐色の強い多色性を示すものと,多色性を示さないものとがあり,短柱状の単結晶の柱面に平行にzoningしているものが多い.通常の薄片の厚さではわからないが,イオン研磨により極めて薄くした薄片ではクロスニコルでバンド状の組織が認められることがある.この蓮華石様鉱物は非常に小さいため,イオン研磨にて試料を作り,透過型電子顕微鏡で解析した.EDSによる定量分析では組成はSiO2=23.0,TiO2=28.3,Fe2O3=0.4,SrO=41.3,ZrO2=6.7,Nb2O5=0.4 wt.%という値が得られた.電子線回折では蓮華石のd001周期が2倍の位置に回折スポットを示し,いくつもの回折パターンの特徴から蓮華石の多形,斜方晶系相と解釈される.Auを標準としたEDパターンの解析から,この鉱物の格子定数はa=14.0,b=5.7,c=21.9Åである.この斜方晶系単位格子は,輝石,角閃石等と類似の,単斜晶系単位格子が格子レベルでの双晶を作った格子関係にある.高分解能像では双晶構造に対応する像が解像される.なお,蓮華石の原構造ともいうべきperrierite (Ce,La,Ca,Sr)4FeTi4 (Si2O7) 2O8,chevkinite(Ce,Ca,Th)4(Fe,Mg) (Ti,Mg,Fe) 4(Si2O7)2O8には斜方晶系の報告はされていない.この蓮華石様鉱物については現在ガンドルフィーカメラ,XMA他でさらに検討中である.

著者

Sayantani CHATTERJEE Debaditya BANDYOPADHYAY Eiichi TAKAZAWA Katsuyoshi MICHIBAYASHI

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.116, no.3, pp.170-175, 2021 (Released:2021-07-17)

参考文献数

27

被引用文献数

1

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Oxidation states within the planetary interior are intrinsically linked with the broad scale tectonism; however, it is difficult to estimate the actual oxidation conditions. Orthopyroxene–magnetite symplectite formed by olivine oxidation may provide a significant clue into such oxidation events. Here we report detailed mineralogical and petrological synthesis of such orthopyroxene–magnetite symplectites from olivine gabbros of Oman Ophiolite (Hole GT2A, ICDP Oman Drilling Project). In order to understand how oxidation affects different olivine compositions, we employed a phase equilibria approach and computed several temperature–composition diagrams at a fixed pressure (1 kbar). Our experiments predict the coexistence of olivine with Fo75–76 and Fo71 with the orthopyroxene (En79 and En76), respectively, which is remarkably similar to the mineral chemistry obtained from the Oman lower crustal gabbros. From the magnetite content, we also infer that the symplectite formation may have taken place over a range of temperatures (600–1000 °C) via subsolidus olivine oxidation and/or melt (oxidizing)–olivine interaction. The latter is more probable, considering the partial occurrence of orthopyroxene and clinopyroxene rim adjacent to the symplectites.

著者

高橋 直樹 荒井 章司

出版者

Japan Association of Mineralogical Sciences

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.89, no.3, pp.101-114, 1994-03-05 (Released:2008-03-18)

参考文献数

26

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Large amounts of basalt gravels are associated with serpentinite gravels in the Senhata Formation of the Miura Group (uppermost Miocene) in the Boso Peninsula, central Japan. The basaltic rocks possibly constitute a presumed mafic-ultramafic complex (“Fudoiwa serpentinite mass”) in the Tokyo Bay area, which belongs to the Circum-Izu Massif Serpentine Belt. They are slightly altered and have phenocrysts of olivine±clinopyroxene±plagioclase; they are sometimes picritic. Chromian spinel is common both as euhedral inclusions in olivine and as microphenocrysts, and clinopyroxene is often titanaugite. Bulk rock chemistry indicates that intraplate alkali basalts are dominant in the Senhata basalt gravels. Relic chromian spinel chemistry also suggests that the alkali basalts and the picritic basalts are of intraplate magma origin. The close association of intraplate basalts with the Fudoiwa serpentinites may be compatible with the presence of Ti-rich wehrlitic cumulates and Ti-rich metasomatites in the Fudoiwa mass reported by Arai et al. (1990). In the Circum-Izu Massif Serpentine Belt, alkali basalts tend to be associated with small-scale serpentinite masses, and tholeiitic ones, with large-scale masses.

著者

Wataru YABUTA Takao HIRAJIMA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.190831, (Released:2020-10-28)

被引用文献数

1

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We present the first report of okhotskite in a lawsonite–blueschist–subfacies metachert of the Hakoishi subunit, Kurosegawa Belt, Kyushu, Japan, which was metamorphosed at peak temperatures and pressures of 200–300 °C and 0.6–0.8 GPa. This okhotskite–bearing assemblage is particularly notable because it formed at higher pressures than that of previously documented okhotskite with available pressure estimations. Textural relationships indicate that okhotskite formed during peak metamorphism in equilibrium with piemontite, Na pyroxene, magnesioriebeckite, braunite, and hematite. Okhotskite shows a significant variation in Fe:Mn ratio (Fetot/Mntot = 0.13–0.56) and a following average empirical formula; (Ca7.62Mn2+0.16)Σ7.78(Mn2+2.71Mg1.29)Σ4.00(Mn3+4.13Fe3+2.26Al1.36V3+0.23Ti0.02)Σ8.00Si11.86O44.02(OH)16.98. Raman spectra of okhotskite are reported for the first time and show characteristic peaks at 362, 480, and 563 cm−1. The stability relationships between okhotskite and other Mn–bearing minerals, such as piemontite, sursassite, spessartine, braunite, and Mn–bearing lawsonite, are examined using a revised Schreinemakers’ analysis. The obtained petrogenetic grid provides tight constraints on the P–T relationship of natural mineral assemblages observed in Mn–bearing cherts within epidote–blueschist–grade and lawsonite–blueschist–grade. Furthermore, this petrogenetic grid predicts that the assemblage of okhotskite and Mn–bearing lawsonite should be stable at higher pressures. The higher–pressure stability suggests that highly oxidized Mn–bearing metacherts can transport water and buffer oxygen in the deeper parts of subduction zones, given that okhotskite and Mn–bearing lawsonite contain high water contents (6.9 and 11.3 wt% H2O, respectively) and trivalent manganese.

著者

高木 秀雄 柴田 賢 内海 茂

出版者

Japan Association of Mineralogical Sciences

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.84, no.1, pp.15-31, 1989-01-05 (Released:2008-03-18)

参考文献数

38

被引用文献数

5 5

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Various metamorphic rocks such as amphibolites (garnet-cpx amphibolite, schistose amphibolite, kyanite-bearing amphibolite), pelitic and basic schists (epidote amphibolite), and ultramafic rocks (spinel lherzolite, pyroxenite, hornblendite) are exposed in the Yoshimi Hills, to the east of the Kanto Mountains. Schistose amphibolites, which have the largest exposure in the Yoshimi Hills, and pelitic schists were moderately suffered mylonitization. The chemical composition of metamorphic minerals such as garnet, cpx and hornblende in the garnet-cpx amphibolite, and garnet in the schistose amphibolite suggests that these rocks were formed under the amphibolite to the granulite facies. The garnet-biotite temperature after Pigage and Greenwood (1982) estimated on the pelitic shcists is more than 800°C, considerably higher than the temperature (610°C) estimated on the pelitic schists in the highest metamorphic grade zone of the Sanbagawa belt in the Shikoku region. K-Ar ages of hornblende are 63.5 Ma for the garnet-cpx amphibolite and 61.0 Ma for the kyanite-bearing amphibolite, whereas K-Ar age of muscovite for the pelitic schist is 34.1 Ma. Form these age data, even though taking a possibility of rejuvenation into consideration, it is difficult to correlate the metamorphic rocks of the Yoshimi Hills to the metamorphic rocks of the Kurosegawa belt. Considering the occurrence of tectonic blocks of various amphibolite masses in the Sambagawa belt in the Shikoku region, it is possible to correlate the metamorphic rocks of the Yoshimi Hills to those in the Sambagawa belt. However, further study is necessary before we come to decide the belongings of the metamorphic rocks in the Yoshimi Hills.

著者

TAKESHI TOMISAKA HANS P. EÜGSTER

出版者

Japan Association of Mineralogical Sciences

雑誌

Mineralogical Journal (ISSN:05442540)

巻号頁・発行日

vol.5, no.4, pp.249-275, 1968 (Released:2008-03-18)

参考文献数

22

被引用文献数

22 28

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The main end members of the sodalite group, that is, chlorine sodalite, bromine sodalite, iodine sodalite, hydroxylsodalite, carbonate noselite, sulfate noselite, chromate noselite, molybdate noselite and tungstate noselite, were synthesized under hydrothermal and dry conditions, and the cell edges ao and cell volumes V of these minerals were determined. These minerals can be divided into two subgroups: the sodalite subgroup, which includes chlorine sodalite, bromine sodalite, iodine sodalite and hydroxylsodalite, and the noselite subgroup, which includes carbonate noselite, sulfate noselite, chromate noselite, molybdate noselite and tungstate noselite. The X-ray powder diffraction patterns of the four end members of the sodalite subgroup make their appearance only as h+k+l=2n. Those of five other end members which belong to the noselite subgroup appear as h+k+l=2n and h+k+l=2n+1. The dissociation temperatures of chlorine sodalite and sulfate noselite are 1230°±5°C in chlorine sodalite and 1255°±5°C in sulfate noselite, and complete solid solution was found to exist between chlorine sodalite (Na8Al6Si6O24Cl2) and sulfate noselite (Na8Al6Si6O24SO4) at temperatures above 1050°C. Compositions of the chlorine sodalite-sulfate noselite solid solutions were determined from the cell edges ao, obtained by measuring the shifts of the 211, 310 and 222 reflections (CuKα). A solvus of the chlorine sodalite-sulfate noselite series was determined at temperatures below 1050°C. Polymorphic relationship was discovered in the sulfate noselite in the noselite subgroup.

著者

Yuji ICHIYAMA Takahito KOSHIBA Hisatoshi ITO Akihiro TAMURA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.191205, (Released:2020-06-26)

被引用文献数

6

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Early Paleozoic serpentinite melanges in Japan preserve the oldest high–P metamorphic rocks in the circum–Pacific orogenic belt. To understand the tectonic regime at the subduction initiation of the proto–Japan convergent plate boundary, whole–rock geochemistry, and zircon U–Pb geochronology were investigated for amphibolite blocks in the Omi serpentinite mélange, central Japan. The studied amphibolites from two different localities have the mineral assemblage of albite + clinozoisite + amphibole ± rutile ± titanite, which characterize epidote–amphibolite facies metamorphism. Whole–rock trace element concentrations of the amphibolites suggest that gabbroic protoliths formed possibly in an oceanic setting. The zircon U–Pb weighted mean ages obtained from two amphibolite samples indicate that the protolith was formed in the Cambrian. The protolith ages of the studied amphibolites are comparable with those of reported Early Paleozoic ophiolite and high–pressure rocks in Paleozoic serpentinite mélanges in Japan. This fact implies that the young hot oceanic crust was subducting into the East Asian convergent plate margin during the Cambrian.

著者

Mayu KAKEFUDA Tatsuki TSUJIMORI Katsuyuki YAMASHITA Yoshiyuki IIZUKA Kennet E. FLORES

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.190731a, (Released:2020-03-04)

被引用文献数

1

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Awaruite (Ni2–3Fe) is a natural occurring Ni–Fe alloy in serpentinite, which represents a better candidate to assess Pb isotope signatures in the mantle wedge since the concentration of Pb in awaruite is almost ten times higher than that in serpentine minerals. Revisiting so–called josephinite from the Josephine Ophiolite confirmed that josephinite is characterized by aggregates of awaruite with minor Ni–arsenide. The Raman spectrum obtained from the josephinite–hosting serpentinite shows diagnostic peaks of antigorite, suggesting josephinite might have formed under stability field of antigorite. Using a stepwise leaching and partial dissolution method, we obtained Pb isotope ratios of josephinite by TIMS. Since all ratios converged to a homogeneous value towards the later steps of the partial dissolution, this allowed to calculate weighted mean values that give precise Pb isotope ratios: 206Pb/204Pb = 18.3283 ± 0.0020 (MSWD = 0.49), 207Pb/204Pb = 15.5645 ± 0.0020 (MSWD = 0.36), and 208Pb/204Pb = 38.0723 ± 0.0061 (MSWD = 0.50); these values can be evaluated as one of the reference Pb isotope ratios in serpentinites from supra–subduction zone ophiolite. The newly obtained Pb isotope ratios of josephinite are consistent with the previous reported isotope ratios, which are characterized by enriched 207Pb/204Pb ratio with MORB–source like 206Pb/204Pb and 208Pb/204Pb ratios. Although these Pb isotope features interpreted as a reflection of arc magmatism in the previous study, the presence of Ni–arsenide and enriched 207Pb/204Pb ratios may indicate an involvement of As–rich fluids derived from slab sediments.

著者

Takeshi SUGIMOTO Tomoyuki SHIBATA Masako YOSHIKAWA Keiji TAKEMURA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.101, no.5, pp.270-275, 2006 (Released:2006-10-14)

参考文献数

29

被引用文献数

16 20

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We have characterized the Sr-Nd-Pb isotopes and major and trace element compositions of 10 Quaternary volcanic rocks from the Yufu and Tsurumi volcanoes in northeast Kyushu, Japan. The enriched incompatible elements, negative Nb, and positive Pb and Sr anomalies are generally interpreted to be from island arc affinities of the lavas. However, the LREE/HREE ratio of the lavas (La/Yb = 8.5 ± 1.3) is greater than that from the island arc intermediate volcanics from northeast Japan (La/Yb = 3.8 ± 0.6), suggesting a different origin. One dacite sample had a Sr/Y ratio > 40, and the SiO2, Al2O3, MgO, Y, Yb, Sr, and 87Sr/86Sr compositions fell within the range of typical adakites. Other lavas were classified as normal island arc-type magmas. These results suggest that a partial melting of the subducting Philippine Sea Plate played a role in the genesis of the Yufu-Tsurumi volcanic rocks. The Sr, Nd, and Pb isotopic compositions show evidence of mixing between melts, derived from oceanic basaltic crust and subducted terrigenous sediments for the adakite magma, whereas another source is required to explain the enrichment in Sr-Nd isotopes and depletion in Pb isotopes of the island arc-type magma. Although the island arc-type magma appears to have a different source, a mixing of the adakite magma with this magma is apparent from our observations of the trace elements and isotopes.

著者

小島 晶二 苣木 浅彦

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.78, no.12, pp.491-496, 1983-12-05 (Released:2008-08-07)

参考文献数

13

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From the Senzai vein of the Oe mine situated in southwestern Hokkaido, some kinds of rhodochrosite stalagmites are sometimes found out at the bottom of druse within the vein. The stalagmites show the shape of column, 2 to 30mm in diameter and 1 to 12cm in length. They consist of irregular fan-shaped crystals superficially and show the solution growth textures such as concentric bandings. These stalagmites have the chemical compositions of 53 to 89 mole % MnCO3, 2 to 20 mole % CaCO3. 7 to 26 mole % FeCO3 and 1 to 9 mole % MgCO3, which are mostly within the compositional region of drusy rhodochrosite of the vein. Chemical compositions of the rhodochrosite stalagmites change markedly with the concentric bands as shown in Fig. 7, which shows considerable increase of MnCO3 content from core to rim. This feature is considered as being due to chemical changes of the ore solution or ground water producing the rhodochrosite stalagmite.

著者

天白 俊馬

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.77, no.4, pp.125-136, 1982-04-05 (Released:2008-08-07)

参考文献数

40

被引用文献数

1

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The Cretaceous Hiroshima granite of the Hiroshima-Iwakuni area is divided petrographically into two types, e. g. biotite granite and hornblende-bearing biotite granite. The dark inclusions in the latter are characterized by containing hornblende commonly, while those associated with the former granite are hornblende-free, tiny in size, and also small in amount. Plotting the chemical compositions on the normative An-Ab-Or diagram, these two types of granite are quite different in trend, although there is no distinct difference on the Thornton-Tuttle's variation diagrams. This cannot be explained by the difference of fractionation and also by the change in partial PH2O of magma under cooling condition. Irregular shape and uneven distribution of hornblende in hornblende-bearing biotite granite indicate that this hornblende was not the crystallization product of granite magma, but was accidental xenocryst transported into the magma. This fact and the difference of trend in the An-Ab-Or diagram suggest the contamination of granite magma by the hornblende-bearing dark inclusions.

著者

藤縄 明彦

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.77, no.12, pp.419-437, 1982

被引用文献数

1 2

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In order to understand the generation and differentiation processes of the island arc tholeiite magma, it is essential to reveal the crystallization sequence of the minerals in the shallow magma chamber.<br> For that purpose, a microprobe study has been undertaken on three Funagata pigeonite basalts which are the most primitive basalts among the island arc tholeiitic series in the Nasu zone, NE Japan. Firstly, the crystallization sequence recognized in each sample has been clarified based on chemical compositions and textural relations. Secondly, information on the near equilibrium crystallization in the shallow magma chamber has been extracted and connected.<br> The crystallization sequence obtained through the study is as follows.<br> Stage A: Plagioclase (An₉₀+), olivine (Fo₇₈), bronzite (Wo_4.5 En₇₆Fs_19.5) and pigeonite (Wo_9.5En₇₁Fs_19.5) coexist with liquid. At this stage, olivine has already been in reaction relation with liquid to form bronzite and/or pigeonite. Bronzite is also in reaction relation with liquid to form pigeonite.<br> Stage B: Mafic minerals gradually enrich in Fe²⁺. When the Mg/(Mg+Fe) ratio of the pigeonite reaches 0.23, augite begins to crystallize. Penecontemporaneously with the start of the augite crystallization, olivine (Fo₇₅) is fractionated from the liquid. An mole % of the plagioclase is nearly constant.<br> Stage C: The three pyroxenes further enrich in Fe²⁺. Three pyroxene coexistence continues until the Mg/(Mg+Fe) of the pigeonite reaches 0.26. Chemical composition of the plagioclase is nearly constant (An₉₀).<br> Experimental data indicate that the crystallization sequence obtained here must reflect the notable change of the pyroxene phase relation in the early stage differentiation of the Funagata tholeiitic basalt magma. This type of change in pyroxene phase relation is interpreted as being due to the successive decrease of the liquidus and solidus temperatures of pyroxenes, accompanied with the proceeding of the differentiation.

著者

佐藤 努 福士 圭介 伊藤 健一 池田 穂高 濱部 和宏 横田 漠

出版者

Japan Association of Mineralogical Sciences

雑誌

日本鉱物学会年会講演要旨集

巻号頁・発行日

pp.47, 2002 (Released:2003-04-18)

著者

関 陽太郎 奥村 公男

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.60, no.1, pp.27-33, 1968-07-05 (Released:2008-08-07)

参考文献数

8

被引用文献数

4 4

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宮城県鬼首地熱地帯に地熱開発のためにほられたボーリングのコアから湯ケ原沸石が発見された。この地熱地帯は,ボーリングコアでの観察によると,深部から浅部にむかって,ワイラカイト,ワイラカイト・ローモンタイト,ローモンタイト,モルデナイト,および無沸石の5つの帯にわけられる。湯ケ原沸石はローモンタイト帯に存在する。湯ケ原沸石のX線データを記し,あわせて湯ケ原沸石の化学成分についてふれた。

著者

三浦 清

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.56, no.6, pp.256-283, 1966-12-05 (Released:2008-08-07)

被引用文献数

1 2 1

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The geology, petrographic characters of the granites, and the types of collapses of the rocks caused by heavy rain fall in the Kamo District, Shimane Prefecture, are described to clarify the relation between rock types and collapsing phenomena in the granite mountain area. The granitic rocks comprise granodiorite and biotite granite, and both are weathered remarkably in most parts. From the genetic point of view, the collapses are classified into six types. 1) Collapse, closely related to the joint structure of the rocks; they occur characteristically at the foot of slopes in the region of weathered granodiorite. 2) Collapse of the weathered zone (uppermost layer covered with vegetation) of slopes, caused by difference of physical properties to the ground water between the weathered zone and the basement rocks. 3) Collapse with characters of (1) and (2). 4) Collapse closely related with dikes in granite. 5) Collapse accompanying landslide in fault breccia zones. 6) Collapse or resliding of the talus deposit, made by an older land slide of the adjoining rock masses. The majority of the collapses in this district belong to types (1), (2) and (3). Types (1) and (2) predominate in granodiorite and (3) in biotite granite.

著者

Kenta YOSHIDA Takao HIRAJIMA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.107, no.1, pp.50-55, 2012 (Released:2012-02-29)

参考文献数

21

被引用文献数

5 5

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Annular fluid inclusions were found in a foliation-parallel quartz vein intercalated with metapelites from the Besshi area of the Sanbagawa belt, SW Japan. The preserved “foam microstructure” of the quartz vein suggests low differential stress at high temperatures for its formation. Three types of fluid inclusions have been identified: the earliest one, FIA-I, is characterized by two phase inclusions arranged along intragranular planes and mainly composed of aqueous saline fluid and CH4 gas; FIA-II texturally comparable to FIA-I consists of CH4-N2-CO2-H2 gas phase inclusions with rare two-phase inclusions; the latest type, FIA-III, is characterized by arrangements along transgranular planes consisting of two-phase inclusions mainly composed of CH4-N2 vapor in aqueous saline fluid. Amongst them, FIA-I contains annular fluid inclusions, which are attributed to reequilibration due to a confining pressure increase, suggesting that the host rock underwent the compression after the entrapment of FIA-I. Textural observations and chemical characteristics show that FIA-I and -II were trapped during prograde or near the peak metamorphic stage, and that FIA-III was probably trapped at an early stage of the exhumation.

著者

Nobuo MORIMOTO

出版者

Japan Association of Mineralogical Sciences

雑誌

Mineralogical Journal (ISSN:05442540)

巻号頁・発行日

vol.14, no.5, pp.198-221, 1989 (Released:2007-03-31)

参考文献数

31

被引用文献数

4 71

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This is the final report on the nomenclature of pyroxenes by the Subcommittee on Pyroxenes established by the Commission on New Minerals and Mineral Names of the International Association. The recommendations of the Subcommittee as put forward in this report have been formally accepted by the Commision. Accepted and widely used names have been chemically defined, by combining new and conventional methods, to agree as far as possible with the consensus of present use. Twenty names are formally accepted, among which thirteen are used to represent the end-members of definite chemical compositions. In common binary solid-solution series, species names are given to the two end-members by the “50% rule”. Adjectival modifiers for pyroxene mineral names are defined to indicate unusual amounts of chemical constituents. This report includes a list of 105 previously used pyroxene names that have been formally discarded by the Commision.

著者

Hidemichi HORI Eiji KOYAMA Kozo NAGASHIMA

出版者

Japan Association of Mineralogical Sciences

雑誌

Mineralogical Journal (ISSN:05442540)

巻号頁・発行日

vol.10, no.7, pp.333-337, 1981 (Released:2007-03-31)

参考文献数

11

被引用文献数

10

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Kinichilite, a new mineral from the Kawazu mine, is hexagonal with a=9.419 Å, c=7.666 Å, space group P63 or P63⁄m. The empirical formula derived from the chemical analysis is: (Fe2+1.13Mg0.47Zn0.43Mn2+0.17)Σ2.20(Te2.97Se0.03)Σ3.00 O9.00(H1.38Na0.22)Σ1.60·3.2H2O, corresponding to Fe2+ dominant analogue of zemannite.It is dark brown in colour. Subadamantine luster and brown streak. No cleavage. Density (calc.) 3.96 g/cm3 from normalized empirical formula and Z=2.

著者

Atsushi ISHIHARA Hiroaki OHFUJI

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.118, no.1, pp.230327, 2023 (Released:2023-11-21)

参考文献数

34

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In this study, we investigated the origin and formation process of zeolitized gastropod fossils in Neogene sediments (Shiote Formation) in Minamisoma, Fukushima, Japan using powder X-ray diffraction, SEM-EDS and micro-Raman spectroscopic analysis. The formation of zeolites was particularly pronounced in the upper chamber, which was not filled with detrital particles, of the gastropod fossils, where tabular crystals of heulandite were observed growing directly from the shell wall. The heulandite crystals are often covered by large euhedral crystals of calcite and occasionally by acicular crystals of mordenite. The formation of zeolite (heulandite) was also observed in the matrix of the host sandstone together with clay minerals (mostly montmorillonite), suggesting that the Shiote Formation experienced moderate metamorphism equivalent to zeolite facies during burial diagenesis. The Si/Al ratio of heulandite was found to decrease gradually from the bottom (∼ 4.5) to the top (∼ 3.1) within single crystals across the threshold (4.0) for clinoptilolite/heulandite classification boundary. This may reflect the increase in temperature of the surrounding environment with increase in the burial depth. The extensive growth of zeolites and calcite inside the gastropod fossils indicates that the shell provided semi-closed spaces in which pore fluid could be retained and condensed during diagenesis, thus promoting the crystal growth from the supersaturated solution.