著者

横山 光 八幡 正弘 岡村 聡 西戸 裕嗣

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.32, no.2, pp.80-95, 2003 (Released:2008-04-21)

参考文献数

26

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Late Pliocene-Pleistocene Akaigawa Caldera, 6-7 km in diameter, is located in southwest Hokkaido. It mainly consists of felsic caldera-forming welded tuffs, somma lavas, and lacustrine deposits in order of decreasing age. Caldera-forming pyroclastic flows of the Nagasawa Volcanics were erupted at the southwestern caldera rim and are characterized by high SiO2 content (76-79%). Contrary to this, the subsequent somma lavas were erupted from multiple vents along ring fractures and have variable SiO2 contents ranging from basaltic andesite to dacite (56.6-66.7%).The whole rock K-Ar age of the lower member of the welded tuffs is 2.06±0.57, whereas the age of the middle member 1.62±0.14 Ma. The Maruyama Lava and the Daikokuyama Lava from the somma lavas give ages of 1.65±0.07 Ma and 1.55±0.06 Ma, respectively. The age of the middle member of the welded tuffs coincides within measurement errors with ages determined for the somma lavas. The age and geological structures of the lower member of the welded tuffs suggest that the pre-Akaigawa, outer Yoichigawa Caldera formation began before 2 Ma. On the basis of petrography and geochemistry, the somma lavas are divided into three units; the eastern somma lavas, the western somma lavas, and the post-caldera central cone. The lithologies of eastern somma lavas range from olivine basaltic andesite to andesite, and the western somma lavas range from quartz andesite to dacite, indicating a similar geochemical trend to that of the eastern somma lavas. The post-caldera central cone is composed of andesite to dacite, and has a different geochemical signature from that of the somma lavas. The volcanic structure, topography, eruption volume, and petrography indicate that the Akaigawa Caldera-collapse took place after eruptions of both welded tuffs and somma lavas, and that the western side of the caldera is characterized by a higher eruption rate of felsic to intermediate magma and more extensive subsidence compared with the eastern side. This may indicate the existence of a heterogeneous magma chamber beneath the Akaigawa Caldera.

著者

片山 信夫 高野 幸雄 加藤 一郎 加藤 敏郎 中川 進

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.2, no.1, pp.46-52, 1954-09-30 (Released:2009-08-11)

参考文献数

12

著者

土屋 卓久 山中 高光

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.27, no.3, pp.137-145, 1998-08-31 (Released:2009-08-11)

参考文献数

17

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Comprehension of metastable states in the course of phase transition, decomposition, melting, crystallization is one of significant subjects in the solid state earth dynamics. The following categories in the electronic, atomic or lattice transformation must be taken into account for the metastable phenomena of the above structure changes; (A) kinetic factor such as nucleation rate, growth rate, rate of compression and depression, heating rate and reaction duration, (B) environmental physical and thermodynamical parameters. In addition to experimental approaches to clarify metastable states, atomistic computer simulations offer informations of the precursor phenomena of structure changes under the desired physical conditions. For an example of these calculations, present MD calculation simulates the mechanism of pressure-induced amorphization of GeO2 and its polymorphic phase transformation of post-rutile phase under hydrostatic and nonhydrostatic conditions.

著者

松原 聰

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.27, no.2, pp.119-120, 1998-05-11 (Released:2009-08-11)

著者

柵山 徹也

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

pp.120611a, (Released:2013-01-24)

著者

山中 高光

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.32, no.3, pp.109-111, 2003-05-30

著者

野田 稲吉

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.7, no.1-2, pp.1-13, 1964-11-30 (Released:2009-08-11)

参考文献数

22

著者

五十公野 裕也 中島 和夫

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.44, no.4, pp.205-209, 2015 (Released:2015-08-30)

参考文献数

14

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Bi minerals have been discovered from the Fukueison mine, situated in the Uetsu region, Tsuruoka City, Yamagata Prefecture, Japan. Bi minerals occur in quartz veins which consist of chalcopyrite, pyrite and chlorite, accompanied by minor molybdenite, sphalerite and arsenopyrite, hosted in the Nishitagawa granodiorite. Bi minerals are composed of bismuthinite as a major constituent and native Bi, Bi-sulfosalts (krupkaite, cosalite and galenobismutite) and Bi-Te-S minerals (tetradymite, joséite-A, joséite-B and ingodite) as minor constituents. From the paragenesis and texture of Bi minerals, these minerals might have been formed by a change of fS2 and fTe2 conditions. Comparing to other Bi-bearing Mo deposits, Inner Zone of Southwest Japan, it is considered that Bi is closely related with Cu mineralization.

著者

平野 伸夫 竹之下 愛 土屋 範芳

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.38, no.5, pp.198-207, 2009-09-30

参考文献数

28

被引用文献数

1 2

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&nbsp;&nbsp;Carbonate hot spring is a natural chemical reaction field for understanding CO₂ geological sequestration as a natural analogue. Natural analogue studies are particularly important to understand the kinetics of mineral precipitation which has potential difficulties in experimental investigations. Carbonate sinter is frequently formed in and around carbonate hot spring, which can be suitable to elucidate mechanisms of carbonate precipitation associated with flushing CO₂.<br> &nbsp;&nbsp;Oku-Okuhachikuro hot spring, located in Kosaka town, Akita Prefecture, NE Japan, is an artificial hot spring after drilling of exploration for the Kuroko-deposits, and it is still active where carbonate sinter has still been forming continuously for more than thirty years after drilling. The temperature of spring water is 44 &deg;C and water pH is 6.2, with discharge rate of 0.08 m³/min. The average chemical compositions of sinter correspond about 80 wt% CaCO₃, and 4 wt% Fe₂O₃, associated with minor (<1 wt% each) SiO₂, MnO, MgO, Na₂O and K₂O. Carbonate sinter is mainly composed of aragonite with a small amount of calcite; an intimate occurrence of these two forms of CaCO₃ is the most characteristic feature of this locality. However, mineral assemblage, texture and structure of carbonate sinter are different in relation to the distance from the blowout point. Near the blowout point, the sinter is well solidified and shows laminar structure having both of calcite and aragonite. Thickness of Ca-rich laminar ranges from 20 to 150 &mu;m and Fe-rich one is from 10 to 80 &mu;m. Calcite and aragonite assemblage is mainly observed in Ca-rich layer. The Fe-rich layer, however, is composed only of aragonite. The sinter along downstream becomes porous and is monomineralic having aragonite as CaCO₃. The observed relations on the special distribution of aragonite/calcite and the possible stability relations of these phases through EPMA and TG-DTA analyses suggest an importance of minor elements (Fe, <i>etc.</i>) in the precipitation of metastable carbonates: this possible effect of the precipitation of metastable phases should be taken into account in the consideration of geochemical processes of CO₂ mineral trapping.<br>

著者

牧野 州明

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.29, no.2, pp.45-51, 2000 (Released:2008-08-30)

参考文献数

22

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Characteristic structure of Cl-amphibole is reviewed, and its application to chemical zoned amphibole from the Ramnes cauldron is summarized.Large ionic radius of Cl− brings geometrical and chemical effects to the amphibole structure. In the Cl-amphibole, the double chain is significantly deformed to fit expanded octahedral strips, which is achieved by substitution of IVAl for Si (geometrical constraint). The Cl− projects toward the A site and there is a interaction between Cl− and cations in the A site (A site constraint). The short range order of Fe2+-Cl− is observed in Cl-amphibole (chemical constraint). These constraints simultaneously control the Cl− content in amphibole and imply that Cl− substitutes for OH− only in the ferro-paragasite or ferro-hastingsite component. Based on these structural considerations on Cl-amphibole, Cl− variations in the zoned amphibole from the Ramnes cauldron were interpreted. The zoning were developed under different fluid conditions in chemistry and temperature.

著者

松原 聰

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.48, no.2, pp.87-88, 2019 (Released:2019-06-05)

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日本新産鉱物情報(2017年)以降,2018年12月末までに確認された日本産新鉱物および新産鉱物,その他について紹介する.太字は少なくとも化学的,結晶学的性質が明らかにされたもので,信頼度が高い.

著者

亀井 淳志 内藤 一樹 高村 早弥香 加々島 慎一 奥澤 康一 関 陽児 渡部 芳夫

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

pp.131211, (Released:2015-04-28)

被引用文献数

1

著者

鈴木 五百紀 秋月 瑞彦 長瀬 敏郎 藤巻 宏和

出版者

一般社団法人 日本鉱物科学会

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.90, no.4, pp.124-131, 1995 (Released:2006-12-26)

参考文献数

42

被引用文献数

1 1

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Orbicular rock from Inusotoba, Shiroishi, Miyagi Prefecture was studied by optical and chemical methods. The orbicules, which are 5∼20 cm in diameter, are divided into two parts, — core and shell. The core is ball-shaped and dark-colored, and consists mainly of fibrous hornblende and chlorite. The shell, which surrounds core, is light-colored and consists of coarse radial anorthite crystals less than l cm long, which are elongated to a-axis. These radial crystals are characterized by micro subgrains of albite twin and parallel-growing crystals. The other type of orbicule is also known, whose shell consists of several alternate layers of mafic and felsic minerals. This latter type of orbicules is never produced together with the former radial type. The matrix, solidified among orbicules, has a heterogeneous texture, which consists of the dark-part of poikilitic hornblende and the light-part rich in euhedral plagioclase.     The forming environment of orbicular rocks is featured by many close-packed orbicules, the flow structure of felsic mineral assembledge in matrix and unmixing of magma including orbicules with the other magma containing plagioclase spherulites. It is considered that orbicules were formed in supercooling magma possibly due to income of another magma.

著者

佐藤 景 石渡 明

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.44, no.3, pp.155-170, 2015 (Released:2015-06-27)

参考文献数

52

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Ishikoshi Andesite is the Middle Miocene, amphibole-bearing, two pyroxene andesite lava flow located in the forearc area of the Northeast Japan arc, which covers the area of 8 km EW and 7 km NS and has the thickness of >180 m. In this study it is divided into peripheral lava (PL) and central lava (CL), which are distributed in the peripheral and central parts of the volcanic edifice, respectively. PL bears groundmass pigeonite or shows higher FeO*/MgO trend with fractionation and CL does not bear pigeonite and lower FeO*/MgO trend, therefore PL is tholeiitic and CL is calc-alkaline. PL shows petrological features that are compatible with crystallization differentiation. CL has several features that suggest magma mixing such as non-equilibrium plagioclase phenocrysts, but evidences for magma mixing are not robust. In comparison to similar lava flows, PL and CL seem to form a composite lava flow because clear geological boundary between PL and CL cannot be observed and FeO*/MgO ratio of CL tend to be higher in the marginal portion. We also find that two-pyroxene equilibrium temperature of CL (760-850 ℃)is lower than that of PL (970-990 ℃). CL should have been too viscous at this temperature (>1010 Pa·s in anhydrous state) to form a dike, thus it should have effused through the vent which PL formed to be composite lava flow with PL. Ishikoshi Andesite has columnar joints rather than platy joints. In comparison to other lava flows which have platy joints in Japan, it is possible that less anisotropic crystals, low eruption temperature (high viscosity) and/or large phenocryst size have prevented Ishikoshi Andesite from formation of foliation along which platy joints develop in the lava.

著者

岡田 敏朗 長瀬 敏郎 今井 裕之 上原 誠一郎

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.46, no.4, pp.117-123, 2017 (Released:2018-01-12)

参考文献数

17

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Sakura quartz, which shows cherry blossom-like texture on the (0001) cross-section, occurs from Obira mine in Oita prefecture, Japan. The unique texture was analyzed by using CL, EBSD, EPMA, BSE, and OPM. The texture includes numerous solid and liquid inclusions, and is composed of Brazil twin lamellae and Dauphine twin domains. The texture would be named as sakura texture after sakura-ishi (cerasite), which was a variety of cordierite. The quartz crystal with the sakura texture grew by two growth stages. At the first stage, numerous inclusions were incorporated into the milky part and the growth bands are indistinct. In contrast, growth bands were clearly observed at the second stage. The sakura texture developed at the first stage. Almost all quartz crystals from Obira mine have the sakura texture, and the texture formed on replacement process at late greisenization. The sakura texture is a characteristic feature of quartz from skarn deposit.

著者

田崎 和江

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.20, no.3, pp.93-104, 1991-07-31 (Released:2009-08-11)

参考文献数

98

被引用文献数

1 1

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The best examples of bacteriogenic mineralization in the geologic record came from the Precambrian Gunflint Iron Formation in Canada. About 250 minerals are now considered to be biomineralization product and the biomass may control their environmental behavior. The bacteria present in almost all places, such as soils, lakes, acid mine drainage, cement concrete, sludge and deep-sea sediments at temperatures from freezing to hundreds degree cen-tigrades and wide range of pH. Recent examples of bacteriogenic mineralization drawn from areas impacted by industrial activity give the evidences that bacteria can support high rate of mineral precipitation. TEM photographs show that bacterial cell wall is essentially occupied by crystalline materials. Interaction between in-organic physical processes and the biological processes occurs at the interfacial of bacteria and solution. Extensive microbial activity in response to environmental change are the most sensitive factors modyfying the surface of our planet.

著者

木村 眞

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.44, no.1, pp.1-9, 2015 (Released:2015-03-05)

参考文献数

59

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Minerals in meteorites give constraints on the formation history of not only meteorites, but the solar system. Here I introduce some characteristic minerals in meteorites. Enstatite chondrites contain abundant unusual sulfide and metallic minerals that were formed under highly reducing conditions. Refractory inclusions were formed in the earliest stage of the solar system. They typically contain Ca-Al-rich minerals. A new mineral, kushiroite, is one of such minerals, and formed under rapid crystallization conditions. Ultrahigh-pressure minerals are commonly encountered both in chondrites and differentiated meteorites, indicative of pervasive impact processes in the early solar system. An eclogitic mineral assemblage encountered in a CR chondrite suggests the possibility that asteroids were primarily larger than previously estimated.

著者

武藤 正

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.6, no.1-2, pp.60-71, 1963-03-30 (Released:2009-09-03)

参考文献数

5

著者

香内 晃

出版者

一般社団法人 日本鉱物科学会

雑誌

日本岩石鉱物鉱床学会 学術講演会 講演要旨集 2003年度 日本岩石鉱物鉱床学会 学術講演会

巻号頁・発行日

pp.1, 2003 (Released:2004-12-31)

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1.はじめに 隕石中のいわゆるプレソーラーダイヤモンドの特徴は次の通りである:i) 同位体異常を示すXeが含まれる,ii) SiCやグラファイトより2-3桁多量に存在する,iii)しかし,炭素同位体はsolarである.これまでにいくつかのモデルが提案されているが,以上の3つの特徴をすべて説明できるモデルは存在しておらず,ダイヤモンドの形成機構はいまだによく分かっていない.そこで,星間分子雲から隕石母天体への進化過程で起こりうる有機物の生成・変成過程を再現する実験を行った.2.実験 本研究では,次の2つの実験を行った:1)分子雲中での氷(H2O:CO:NH3:CH4=4:2:2:1)への紫外線照射による有機物の生成と,その有機物が低密度雲でさらに105年紫外線照射を受ける過程を再現する実験,および,2)分子雲有機物が炭素質隕石母天体に取り込まれた後に起こる,水質変成・熱変成を再現する実験.3.結果 1)分子雲で生成された有機物は,電子線回折ではハローパターンを示すが,高分解能電子顕微鏡観察では1 nm程度のダイヤモンド微結晶(または,ダイヤモンド前駆体)とグラファイトの存在が明らかになった.さらに,低密度雲でのさらなる紫外線照射によりダイヤモンドが5 nm程度まで成長することがわかった. 2)分子雲有機物の炭素質隕石母天体での水質変成(100-200oC)および熱変成(200-400oC)により,ダイヤモンド,グラファイト,アモルファスカーボン,カルビンが形成されることが明らかになった.4.議論 隕石中のいわゆるプレソーラーダイヤモンドは炭素星や超新星起源ではなく,星間雲起源だと考えるとこれまで問題になっている以下の事を無理なく説明できる:i)SiCやグラファイトより2-3桁多量に存在することは当然である,ii) 炭素同位体も太陽系と同じ物質からできたので同じで当然である,iii) 超新星起源のXeが星間雲の有機物に打ち込まれ,これがダイヤモンドに取り込まれた.また,プレソーラーダイヤモンドに起源の異なるものがあることや,彗星起源の惑星間塵は小惑星起源の惑星間塵と比べてダイヤモンドの含有率が低いことは,プレソーラーダイヤモンドの一部が隕石母天体で形成された可能性を示唆する.

著者

藤井 動

出版者

一般社団法人 日本鉱物科学会

雑誌

鉱物学雜誌 (ISSN:04541146)

巻号頁・発行日

vol.5, no.3, pp.167-180, 1961-07-30 (Released:2009-08-11)

参考文献数

28