著者

Mutsuko INUI Shuto KOJIMA Yoshiya NAGATSUMA

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.221219c, (Released:2023-10-04)

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Albite porphyroblasts occur in schists in higher-grade zones of the Sanbagawa metamorphic belt, Japan. In this study of pelitic schists from the Nagatoro area of the belt, various microstructures in albite porphyroblasts were identified and indicate that grain size reduction of the albite porphyroblasts occurred after their formation. Schists with recognizable porphyroblasts contain fine grains of albite aligned in the matrix. In comparison, schists without recognizable albite porphyroblasts contain lenticular aggregations of albite grains in quartz-rich layers that suggest grain size reduction of the original porphyroblasts. These observations suggest that the absence of albite porphyroblasts does not necessarily indicate different pressure, temperature, or chemical conditions but can instead be explained by grain size reduction of albite porphyroblasts during deformation.

著者

渡辺 一徳 勝井 義雄

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.71, no.2, pp.44-49, 1976-02-05 (Released:2008-08-07)

参考文献数

16

被引用文献数

28 30

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阿蘇カルデラ内北部の本塚・北塚・灰塚はいずれも石英安山岩の溶岩からなる古い中央火口丘で,それらの下底部には海抜約510mのレベルまで水冷により破砕された溶岩が発達している。故にこの水中溶岩が噴出した時期にはカルデラはこのレベルまで湖であったと推定される。この水中溶岩は大小の岩塊と同質の細片からなり,その中には枕状溶岩に類似した柱状節理をもつ岩塊が含まれている。この種の岩塊は多くの点で通常の枕状溶岩とは異なっているので,偽枕状溶岩と呼ぶことにする。その産状の詳細な観察によれば,偽枕状溶岩は,水中を前進中の粘性の高い溶岩に湾曲した割れ目がはいり,これに沿って侵入した水で急冷され,分離したものである。このため偽枕状溶岩は表面に垂直な柱状節理を生じているが,通常の枕状溶岩とちがって外形はもとの流理構造を明瞭に切っている。

著者

MAMI TAKEHARA KENJI HORIE TOMOKAZU HOKADA SOTARO BABA ATSUSHI KAMEI IPPEI KITANO

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.230331, (Released:2023-09-07)

被引用文献数

2

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The Napier Complex in East Antarctica has a complex thermal history, including ultra-high-temperature (UHT) metamorphism. Geochronology, trace element, and isotope geochemistry of zircon, apatite, and monazite in three felsic gneisses collected from Harvey Nunatak were studied using a sensitive high-resolution ion microprobe (SHRIMP) for the first time. Most zircons showed nebulous to fir-tree zoning, which is a common feature of zircons in granulite facies rocks, regardless of the core or rim. The U-Pb dating and rare earth element abundance of zircon indicated that zircon crystallization by regional metamorphism continued from 2567–2460 Ma, consistent with the previously proposed timing of UHT metamorphism. The zircon grains contained a large amount of Li (59–668 ppm). Li was incorporated with Cl at the interstitial sites of the zircon structure, and the zircons crystallized in melts with an abundant supply of Li and Cl. Monazite crystallized from apatite after the UHT metamorphism events of 2071 Ma and 1799 Ma. The U-Pb system of apatite was completely disturbed by the crystallization of monazite at 1785 Ma. In addition, the U-Pb systems of apatite and monazite were disturbed at approximately 500 Ma.

著者

Naoki HIRAKAWA Yoko KEBUKAWA Takazo SHIBUYA Hisahiro UEDA Kensei KOBAYASHI

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.220913, 2023 (Released:2023-07-26)

参考文献数

53

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Several investigations have demonstrated that olivine may be used to simulate geochemical and cosmochemical reactions. Since olivine in extra-terrestrial samples has varying forsterite numbers and natural olivine contains inevitable impurities, synthetic olivine with the requisite forsterite number has been prepared for various experimental research. This study aimed to synthesize Fe-bearing olivine via synthetic experiments conducted at near-solidus temperatures and elucidate the formation and decomposition mechanisms of the obtained Fe-bearing olivine. Specifically, we attempted to synthesize Fo60 [Forsterite number = 100 × Mg/(Mg + Fe) = 60] olivine using a mixture of analytical-grade SiO2, MgO, and Fe2O3. To clarify the stability of the obtained olivine, the temperature range (1350-1500 °C) and heating durations (1.5 or 15 h) were controlled under a constant oxygen fugacity of QFM-1 log units.The target olivine (Fo60) was obtained via heating for 1.5 h at 1500 °C, corresponding to the solidus line temperature. However, maintaining the olivine obtained at this temperature for 15 h resulted in a much higher forsterite number owing to the formation of oxidized minerals of olivine (magnetite and pyroxene). Similar oxidation products were also obtained following heating at 1450 °C for 15 h. These results indicated the primary formation of Fe-bearing olivine during 1.5 h of heating and its subsequent decomposition to magnetite and pyroxene owing to the high-temperature oxidation at near-solidus temperatures during heating for 1.5-15 h. These findings highlight a strategy for synthesizing Fe-bearing olivine and the associated mechanism and provide experimental insights into the decomposition of olivine in natural igneous rocks.

著者

Kazumasa SUEYOSHI Manami KITAMURA Xinglin LEI Ikuo KATAYAMA

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.221014, 2023 (Released:2023-04-13)

参考文献数

32

被引用文献数

1

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The frequency characteristics of acoustic emission (AE) during triaxial compression of thermally cracked and unheated (‘fresh’) granite samples were investigated with the aim of understanding the influence of pre-existing cracks on precursor information regarding macroscopic failure. The peak frequency during the damage process was the same for thermally cracked and fresh granites. Analysis of AE signals showed that signals with low peak frequency appeared before failure of the sample, implying the initiation of macrocracks with progressive growth of cracks. The peak amplitude of the frequency spectrum recorded in the thermally cracked samples was much lower than that in the fresh samples. This result suggests two reasons for the difference in peak amplitude: reduction in shear modulus and the attenuation filtering phenomenon caused by thermal cracks (i.e., the differences in overall bulk properties). In particular, the maximum value of peak amplitude in the low-frequency band for the thermally cracked samples was smaller than that for fresh samples. This characteristic can be related to the properties of source of AE signals, such as the stress drop and crack size. Assuming that pre-existing thermal cracks grow during the pre-failure stage, the events with low peak frequency and low peak amplitude in the heat-treated samples are interpreted as exhibiting a low stress drop for individual events. Therefore, although AE signals with low frequency can be considered as precursors to rock failure, cracking behavior suggested by events with low frequency depends on the initial damage condition of the rock sample.

著者

Tetsuo KAWAKAMI Simon L. HARLEY

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.230131b, (Released:2023-04-25)

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Boron isotope compositions were measured in kornerupine and tourmaline from lenses consisting primarily of kornerupine, plagioclase and corundum. The lenses occur within hornblende-gneiss or along the boundary between this gneiss and an amphibolite lens at Akarui Point in the Lützow-Holm Complex, Prince Olav Coast, East Antarctica. The peak metamorphic conditions have been estimated to be ~ 800-900 oC and ~ 8-11 kbar. The δ11B compositions of kornerupine, which is interpreted to have been a stable phase at the metamorphic peak, are -11.6 ± 0.4 to -7.8 ± 0.5 ‰ and -9.8 ± 0.3 to -6.1 ± 0.2 ‰ in two different samples. Grains of prograde tourmaline included in kornerupine and corundum yielded δ11B = -2.1 ± 0.3 to +0.6 ± 0.3 ‰, and the secondary tourmaline replacing kornerupine yielded δ11B = -4.6 ± 0.2 to -3.7 ± 0.2 ‰. Therefore, the isotopic fractionation between kornerupine and tourmaline, △11BTur–Krn (= δ11BTur - δ11BKrn), of the average prograde tourmaline and average host kornerupine is +6.7 ± 1.5 ‰, which is interpreted to indicate isotopic equilibrium at the metamorphic peak on the basis of previous studies of isotope fractionation between tourmaline and minerals of the kornerupine-prismatine series. The δ11B values obtained on prograde tourmaline are between whole rock δ11B of MORB and mantle rocks and of some sedimentary rocks, and are similar to the δ11B of blackwall tourmalines that crystallized during the decompression stage following high-pressure metamorphism. We infer that the syn-metamorphic B-bearing fluid present in the kornerupine-plagioclase-corundum lens is likely sourced from a mixture of sedimentary, mafic and ultramafic lithologies in a subduction setting. The metabasic and meta-ultramafic lenses found in Akarui Point could be interpreted as the remnant of mixing zone of Ediacaran to Cambrian subduction channel.

著者

Fumiko Higashino Tetsuo Kawakami Tatsuro Adachi Masaoki Uno

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.230131a, (Released:2023-04-21)

被引用文献数

1

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This paper reports multiple fluid infiltration events during retrograde metamorphism in the Sør Rondane Mountains, East Antarctica. Pelitic gneisses from southern part of Perlebandet have cordierite-biotite intergrowth rimming garnet, implying that garnet breakdown occurred by fluid infiltration. Using the Raman peak of CO2 in cordierite and Cl-bearing composition in biotite, this study revealed that the cordierite-biotite intergrowth was formed in equilibrium with one-phase CO2-Cl-H2O fluid. The intergrowth texture is cut by thin selvages composed of Cl-bearing biotite, suggesting Cl-bearing fluid infiltration. Since andalusite is exclusively observed in the selvage, near isobaric cooling path is presumed for the pressure-temperature (P-T) path of these post-peak fluid-related reactions. The inconsistence with counter-clockwise P-T path reported from northern Perlebandet is probably due to the granodiorite/leucocratic granite bodies beneath the studied metamorphic rocks. In order to understand the tectonic evolution at the final stage of Gondwana amalgamation, therefore, effect of hidden igneous rocks needs to be taken into consideration.

著者

Hiroshi MORI Tetsuya TOKIWA Hiroki MIZUMURA Kohei YOSHIKAWA Yuki NOBE 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.221215, (Released:2023-04-14)

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We estimated the protolith age and peak metamorphic temperature of the Yokokawagawa metamorphic rocks (YMR) east of the Itoigawa–Shizuoka Tectonic Line using detrital zircon U–Pb dating and Raman carbonaceous material geothermometry, respectively. U–Pb dating of a psammitic rock yielded a youngest age of ∼100 Ma, which corresponds to the protolith age. Raman carbonaceous material geothermometry results for five pelitic rock samples give metamorphic temperatures of ∼350–380 °C. The protolith age is consistent with those of the Sanbagawa metamorphic rocks (SMR), strongly indicating that the YMR are an extension of the SMR. The increase in peak temperature toward intrusive rocks along the eastern margin of the YMR may indicate that the relatively young ages yielded by previous K–Ar dating of the YMR reflect thermal resetting due to contact metamorphism.

著者

田辺 行雄 柴草 英彦 平島 崇男

出版者

Japan Association of Mineralogical Sciences

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.88, no.10, pp.463-468, 1993-10-05 (Released:2008-03-18)

参考文献数

7

被引用文献数

3 3

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A BASIC program to calculate the Schreinemakers' bundle is designed for NEC 9800 series computer. Algorithms for determining stable univariant lines and combing stable invariant points are newly devised following the graphic theory. The computer program can solve all possible sets of invariant points in model systems with up to (C+5) phases. For model (C+3) phases systems, the program automatically displays all possible nets on a video screen.

著者

Takashi HOSHIDE Masaaki OBATA Takashi AKATSUKA

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.223-239, 2006 (Released:2006-10-14)

参考文献数

43

被引用文献数

21 23

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The Murotomisaki Gabbroic Complex is a sill-like layered intrusion of up to 220 m in thickness and is located at Cape Muroto, Kochi Prefecture, Japan. There are several olivine-rich zones within the intrusion, which may have been formed through accumulation of olivine crystals. However, up to now it has not been clear as to whether all of the olivine-rich zones formed in this way. To clarify this, we reinvestigated the layered structure by collecting a consistent data set of modal composition, crystal size, and crystal number density of olivine from throughout the intrusion. It was found out that nearly all of the olivine crystals, in terms of crystal numbers, occur in the basal olivine-rich zone (within 40 m of the base of the intrusion), and the average value of the crystal number density of olivine throughout the entire intrusion coincides with the crystal number density of olivine in the outermost parts of the lower and upper chilled margins. Hence, we conclude that most primary olivine phenocrysts within the magma settled under the influence of gravity and accumulated to form the basal olivine-rich zone. The crystal number density of olivine within the mid-level zones (40-100 m from the base of the intrusion) is much less than the initial values, as indicated by values recorded in the chilled margins. It is proved that the increase of the olivine mode within this zone is attributed not to the crystal accumulation of olivine but to the increase of the crystal size of olivine, i.e., the crystal growth. In this way, considering the mode, crystal size, and crystal number density of olivine throughout the intrusion, the olivine-rich zones within the intrusion can be classified, in terms of their origin, as either crystal accumulation zone (AC zone) or crystal growth zone (GR zone). The growth of olivine crystals in the GR zone was apparently accompanied by an increase in MgO, FeO, and MnO concentrations to levels well above initial (i.e., the chilled marginal) values. This enrichment suggests that crystal growth occurred within a chemically open system in the sense that the increase in MgO content within the GR zone arose from material transfer between the boundary layer (the GR zone) and the overlying magma.

著者

Takehiro HIRAYAMA Tomoyuki SHIBATA Masako YOSHIKAWA Khadidja ABBOU–KÉBIR Kosuke KIMURA Yasuhito OSANAI Kaushik DAS Yasutaka HAYASAKA 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.117, no.1, pp.211217b, 2022 (Released:2022-11-30)

参考文献数

40

被引用文献数

1

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Granitic and gabbroic xenoliths have been found within dacitic lavas in the Hime–shima volcanic group (HVG) of northeastern Kyushu, Japan. The HVG is located near the boundary between the Ryoke and Sangun belts, suggesting that the HVG and associated crustal xenoliths may provide insights into the subsurface distribution of the Ryoke and Sangun belts in Kyushu. This study focuses on xenoliths obtained from the coastal boulders near the Kane Lava of the HVG. The HVG xenoliths consist of gabbro, gabbroic diorite, amphibolite, gneiss, basaltic andesite, and tuffaceous sandstone, with the latter two types resembling those found in the basement rocks of the HVG. The gabbroic xenoliths are geochemically similar to gabbros in the Ryoke belt. The U–Pb dating for zircon in the gneiss xenoliths yielded a metamorphic age of ~ 111 Ma with Th/U values <0.1, similar to the age obtained for metamorphic rocks in or of the Ryoke belt. The new data presented in this study indicate that the xenoliths in the HVG were derived from basement units associated with the Ryoke belt, which in turn, means that the HVG is tectonically underlain by the Ryoke belt. This also suggests that the Ryoke belt extends further north in Kyushu than was previously considered, as implied by the presence of this belt directly below the HVG.

著者

Daisuke NISHIO–HAMANE Koichi MOMMA Masayuki OHNISHI Sachio INABA

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.117, no.1, pp.220728, 2022 (Released:2022-11-29)

参考文献数

24

被引用文献数

1

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Oxyyttrobetafite–(Y) is the first member in the betafite group of the pyrochlore supergroup found in albite–rich pegmatite from Souri Valley, Komono, Mie Prefecture, Japan. This new mineral occurs as small anhedral grains with sizes of 20 to 200 µm in cylinder–shaped aggregates with a substrate of thalénite–(Y) and synchysite–(Y). Small amounts of aeschynite–(Y), thorianite, and thorite are also associated in the same occurrence with oxyyttrobetafite–(Y), and gadolinite–(Y) is also included at the boundary between the aggregate and albite. The physical properties are: brown in color, brittle, transparent, non–fluorescent, vitreous luster, white streak with a Mohs hardness of 5, and a calculated density of 5.54 g·cm−3. Oxyyttrobetafite–(Y) is an optically isometric material with brown color under the microscope with a refractive index of n = 2.3 calculated using the Gladstone–Dale relationship. The empirical formula of oxyyttrobetafite–(Y) calculated on the basis of B = 2 with A2B2X6Y composition is (Y1.58Dy0.13Yb0.07Er0.06Tm0.05Gd0.04Ho0.03Sm0.02Tb0.02Eu0.01Lu0.01)Σ2.02(Ti1.85Ta0.09Fe0.05Sn0.02Nb<0.01)Σ2O7.05 and leads to the ideal formula of Y2Ti2O6O, which requires TiO2 41.44 wt% and Y2O3 58.56 wt%, total 100 wt%. The structure is isometric cubic with the space group Fd3m and unit cell parameters of a = 10.11090(10) Å, V = 1033.64(3) Å3, and Z = 8 by single crystal X–ray diffraction measurements. The seven strongest peaks in the powder X–ray diffraction pattern [d in Å (I/I0) hkl ] were 2.918(100) 222, 2.527(18) 400, 2.321(13) 331, 1.788(53) 440, 1.525(46) 622, 1.162(13) 662, and 1.033(9) 844 with unit cell parameters of a = 10.121(3) Å, V = 1036.6(9) Å3, and Z = 8. The crystal structure was refined to R1 = 0.018 for 159 observed reflections with the criteria of I > 2σ (I ). Oxyyttrobetafite–(Y) is characterized by Y dominance at the A sites, Ti dominance at the B sites, and O dominance at the X and Y sites in the A2B2X6Y pyrochlore–type formula.

著者

Yu ITAMI Daisuke NAKAMURA Atsushi YASUMOTO Takao HIRAJIMA Martin SVOJTKA

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.117, no.1, pp.220221, 2022 (Released:2022-10-28)

参考文献数

52

被引用文献数

1

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The origins of eclogite associated with garnet peridotite in continent–continent collision belts are still debated. We performed petrological studies of eclogites collected from a garnet peridotite block from Nové Dvory in the Gföhl Unit of the Moldanubian Zone in the Variscan orogenic belt, Czech Republic. The eclogite was divided into three types: one kyanite (Ky)–bearing and two Ky–free types. Garnet and omphacite in the Ky–bearing eclogite have lower Fe contents than those in the Ky–free eclogite. Furthermore, the Ky–free eclogite was divided into two types on the basis of Ca content in garnet: Ca–rich (Xgrs > 0.32) and Ca–poor (Xgrs < 0.32) types, except for Ca–poor rim compositions. Application of conventional geothermobarometers to the Ky–bearing type and the Ky–free type with Ca–rich garnet yielded similar pressure–temperature (P–T) conditions (3.2–4.8 GPa and 920–1160 °C) to those of previous studies, whereas the Ky–free type with Ca–poor garnet yielded slightly lower P–T conditions (3.1–3.4 GPa and 950–990 °C) than the other two types. The observed chemical variation of garnet is probably due to the difference in origins, whereby, according to our new results and previous findings, the Ky–bearing eclogite was derived from plagioclase–bearing crustal gabbro, whereas the Ky–free eclogite with Ca–rich garnet was derived from a crystal cumulate possibly in the mantle wedge. In the Ky–free eclogite samples with Ca–poor garnet, chemical compositions of garnet and omphacite are different from those in the other Ky–free samples, and those samples with Ca–poor garnet would have a different origin from the others. One of the Ky–free type with Ca–poor garnet retains garnet grains with chemical zonings probably created during the prograde history, although the eclogite underwent the extremely high temperature (~ 1000 °C) metamorphism. Calculated diffusion distances in garnet reach 0.5 mm during 2 million years, even if we adopted a low value of diffusion coefficient data. Thus, the residence time of the eclogite at the peak meatamorphic conditions would have been shorter than at least 2 million years. The subsequent decompression and cooling after the peak metamorphism were also probably very fast to avoid the chemical homogenization of garnet.

著者

牧嶋 昭夫 中村 栄三

出版者

Japan Association of Mineralogical Sciences

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.88, no.11, pp.499-516, 1993-11-05 (Released:2008-03-18)

参考文献数

69

被引用文献数

3 3

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In this paper (Part I), recent progress in U-Pb dating of zircon is reviewed. Rare-earth element (REE) partitioning of accessory minerals and REE geochemistry of zircon will be reviewed in separate papers, Part II and Part III, respectively. Zircon (ZrSiO4) is one of the most important minerals in geochronology because the zircon crystal is very resistant to alteration, metamorphic and magmatic events. Zircons therefore preserve their primary chemical properties, especially very high U and Th and extremely low Pb contents, in many cases, resulting in most Pb in zircon to be time-integrated radiogenic origin. For the above reasons, zircon has been extensively used in geochronology for over 30 years. Conventional U-Pb dating of zircon has been performed using a thermal ionization mass spectrometer with isotope dilution (IDTIMS). With improvements in the techniques for the elimination of discordant parts and the chemical decomposition of zircon, it is now possible to measure U-Pb age with IDTIMS not only of a sircon grain but also of fragments of a single zircon grain. Recently, the single zircon evaporation technique has been developed to analyze for U/Pb only the closed-system domains in a single grain without chemical treatment. The most outstanding advance in U-Pb dating of zircon has been achieved by the development of secondary ion mass spectrometry (SIMS). Using the SHRIMP (Sensitive High Resolution Ion Micro Probe) at Australian National University, a very small area (<40, μm) can be analyzed, making it possible to reveal with precise age determinations the multiple growth history in a single grain of zircon. However, one of the major problems in the SIMS analysis resides in preparation of a homogeneous zircon standard. The U and Pb concentrations and the Pb isotope ratios of the standard must be known but they can only be obtained by the conventional IDTIMS method. The conventional IDTIMS is, therefore, a prerequisite for SIMS U-Pb dating. The oldest zircons, recorded >4.OGa, have been found with SHRIMP. The existence of such old zircons was confirmed by results obtained by IDTIMS and the single zircon evaporation technique with TIMS. Characterization of the latent primitive crust, based on the chemical compositions of the detrital zircons and their measured ages, has been attempted.

著者

Yuta TSUCHIYA Masahiro KAYAMA Hirotsugu NISHIDO Yousuke NOUMI

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.110, no.6, pp.283-292, 2015 (Released:2015-12-27)

参考文献数

34

被引用文献数

7 8

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Color cathodoluminescence (CL) images of zircon from southern Malawi (MZ) show mottled yellow CL emissions on a dull luminescent background by the annealing below 600 °C, and relatively homogeneous blue emissions above 800 °C. CL spectroscopy of the samples reveals a change of the luminescent features with an annealing temperature, and explains a variation of their colors and luminance observed by a CL microscope. Emission bands at 310 and 380 nm in an ultraviolet (UV) to blue CL are assigned to intrinsic centers in host lattice, narrow peaks at 475 and 580 nm to Dy3+ impurity centers, and broad bands at 500 to 650 nm to Frenkel–type defects and SiOmn− groups. The former two show increases in emission intensities against annealing temperature, but the latter exhibits an increase in intensity up to 300 °C and a decrease above 300 to 700 °C. An increase in an annealing temperature leads to a reproduction of the intrinsic centers, which is responsible for an increase in UV–blue emission, in host lattice accompanied with a recrystallization from metamict state. An increase in the intensities of narrow peaks activated by Dy3+ impurities may result possibly from a recovery of ionization due to the self–radiation and an energy transfer of other REEs to Dy3+ activator. A gradual increase in yellow emission bands up to 300 °C might be caused by a migration of the hole around a thermally–instable lattice defect and/or activated impurities into a more stable site related to Frenkel–type defects and SiOmn− groups, whereas the yellow should be subsequently reduced due to an elimination of these defects.

著者

松原 聰 加藤 昭

出版者

Japan Association of Mineralogical Sciences

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.88, no.11, pp.517-524, 1993-11-05 (Released:2008-03-18)

参考文献数

10

被引用文献数

1

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愛知県新城市中宇利鉱山の旧坑からgaspeite, glaukosphaerite, mcguinessiteおよびjamboriteを発見した。 Jamboriteは鉱山付近の瓶割峠の採石場からも発見された。GaspeiteはCo/(Ni+Co)=0.28-0.31, glaukosphaeriteはNi/(Ni十Cu)=0.42~0.49, CoO 5% (重量)程度まで含む。これらの種では含Co変種は最初の発見である。Mcguinessite中ではMg/(Cu+Mg)=0.61~0.65で原記載より高い値を示す。瓶割峠産のJamboriteはFe/(Fe+Ni)=0.29~0.32で,化学組成変化をFeに富む側に拡げている。これらはすべて蛇紋岩を切る割目に着生する皮膜をなし,成因的に循環地表水と関係がある。これらの中の金属元素はその起源を皮膜下の含Ni蛇紋石, heazlewoodite, cobaltpentlanditeおよびdjurleiteによっているように見える。これらの炭酸塩中でのNi2+に対するCo2+の置換関係はこのような固溶体が容易に生成される旧坑内の条件下での地球化学的挙動の類似性を暗示している。

著者

宮下 敦 今井 直哉

出版者

Japan Association of Mineralogical Sciences

雑誌

岩鉱 (ISSN:09149783)

巻号頁・発行日

vol.89, no.6, pp.227-232, 1994-06-05 (Released:2008-03-18)

参考文献数

10

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Fine lamellar textures with chemical contrast are found in anisotropic grandite garnet from the skarn at the Kamaishi mine, Iwate Prefecture. The lamellae are charaterized by enrichment of iron; i. e., the compositional difference between lamellae and matrix amounts to 5 to 10 mole % in andradite molecules. In the sections sliced normal to (110) faces of garnet, the development of lamellae showing orientation parallel to (111) nearly normal to the growth zoning paralell to (110) face. Furthermore, the fine compositional bands (parallel to (110) growth zoning) are observed cutting the (111) lamellae clearly. The data cannot confirm that formation of lamellae normal to (110) occurs in subsolidus or not. However, the compositional band parallel to (110) is obviously results of subsolidus decomposition.

著者

AKIRA KATO KUNIHIKO SHINOHARA

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.276-284, 1968 (Released:2008-03-18)

参考文献数

10

被引用文献数

7 10

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The first roquesite in Japan found in a magnetite-bearing massive chalcopyrite ore from the subvolcanic ore deposits of the Akenobe mine, Hyogo prefecture was determined by electron microprobe analysis giving Cu, 24.9; Fe, 1.8; Mn, 0.2; Zn, 0.1; In, 46.3; S, 25.7; total, 99.0%, and was studied under the ore microscope. Mineral assemblage with this specimen was found to be different from that of the original French roquesite, which may be due to the special condition of its formation, or possibly a lower Eh condition. Occurrence of some indium minerals in Japanese subvolcanic ore deposits suggests the presence of an ‘indium ore province’.

著者

Tatsuki TSUJIMORI

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.112, no.5, pp.217-226, 2017 (Released:2017-11-15)

参考文献数

67

被引用文献数

13 14

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Paleozoic jadeitite–bearing serpentinite–matrix mélange represents the oldest mantle wedge record of a Pacific–type subduction zone of proto–Japan. Most jadeitites are fluid precipitates (P–type), but some jadeitites are metasomatic replacement (R–type) which preserve relict minerals and protolith textures. The beauty and preciousness of some gem–quality, semi–translucent varieties of jadeitites in the Itoigawa–Omi area led to the designation of jadeitite as the national stone of Japan by the Japan Association of Mineralogical Sciences. Zircon geochronology indicates jadeitite formed prior to Late Paleozoic Renge metamorphism that formed blueschist and rare eclogite. For example, in the Itoigawa–Omi and Osayama localities, older jadeitites and younger high–pressure/ low–temperature metamorphic rocks in a single mélange complex imply different histories for the subduction channel and jadeite–bearing serpentinite–matrix mélange. This suggests that the jadeitite–hosted mélange (or serpentinized peridotite) can stay within the mantle wedge for a considerable time; thus recrystallization, resorption, and re–precipitation of jadeitite can continue in the mantle wedge environment. Therefore, studies of Paleozoic jadeitites in Japan have great potential to elucidate the earliest stages of orogenic growth (oceanward–accretion and landward–erosion) associated with the subduction of the paleo–Pacific oceanic plates, and to test geophysical observations of modern analogues from a mixture of fossilized mantle wedges and subduction channels.

著者

Kazumasa SUGIYAMA Toru KAWAMATA Takahiro KURIBAYASHI

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.210318, (Released:2021-11-09)

被引用文献数

1

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The crystal structure of prehnite Ca2(Al, Fe)(Si3AlO10)(OH)2 from Upper New Street Quarry, Paterson, Passaic County, New Jersey, USA was determined by single–crystal X–ray diffraction. The converged structural model in the space group P 2cm [a = 4.63309(9) Å, b = 5.4839(1) Å, c = 18.5100(3) Å, Z = 2] allowed for the investigation of an ordered Si/Al distribution together with the feasible hydrogen positions inferred from the difference Fourier maps.