著者

Taro KIDO Masanori KUROSAWA Kei IKEHATA

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.220910, (Released:2023-02-10)

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Hydrocarbon fluid inclusions in authigenic quartz from the Jurassic Torinosu Limestone and associated sediment at Sakawa town, Japan, were studied by microthermometry, ultraviolet (UV) fluorescence, and Raman spectroscopy. The quartz contained abundant liquid hydrocarbon and subordinate vapor hydrocarbon fluid inclusions, and tiny solid inclusions of bitumen, calcite, and rarely pyrite. Aqueous fluid inclusions and aqueous components in hydrocarbon inclusions were absent. Under UV irradiation, most of the liquid inclusions from the limestone and associated sediment displayed intense whitish-blue and deep-blue luminescence, respectively. Further, these liquid inclusions were homogenized at around 24 °C and 53 °C, respectively. Small numbers of liquid inclusions from the associated sediments contained a liquefied gas-condensate. Raman measurements indicated the presence of aromatic compounds and the absence of H2O or CO2 molecules in the liquid and vapor inclusions.

著者

Yuzuki SHINJI 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.114, no.1, pp.26-32, 2019 (Released:2019-03-08)

参考文献数

40

被引用文献数

7 8

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Retrograde pumpellyite was newly found in garnet blueschist that is Mg–rich equivalent of late Paleozoic retrograde eclogite of the Yunotani Valley in the Omi area, Hida–Gaien Belt. The pumpellyite with high Al/(Al + Mg + Fe) occurs in pressure shadows around garnets; it is associated with secondary glaucophane, epidote, chlorite, titanite, phengite, albite, and quartz, which all characterize a retrograde blueschist–facies mineral assemblage after peak eclogite–facies mineral assemblage. This feature is comparable with retrograde pumpellyite in late Paleozoic garnet blueschist (with relict eclogite–facies mineral assemblage) in the Osayama area of the Chugoku Mountains. Equilibrium phase calculation confirmed that the pumpellyite is stable at a low temperature and pressure portion of the lawsonite–blueschist–facies. T–bulk–composition (Mg) pseudosection suggests that pumpellyite appears preferentially in high Mg/(Mg + Fe) bulk composition. The limited occurrence of retrograde pumpellyite in the Yunotani garnet blueschist and retrograde eclogite would be explained by Mg–rich bulk compositions. Also, the limited occurrence in pressure shadows around garnets suggests that the fluid trapped in the pressure shadows might have enhanced growth (or precipitation) of pumpellyite. This finding provides a strong evidence that the deeply subducted (eclogite–facies) metabasaltic rocks both in the Hida–Gaien Belt and the Chugoku Mountains were subjected to a very similar blueschist–facies overprinting locally reached the pumpellyite stability field. The ‘Franciscan–type’ cooling path suggests a ‘steady–state’ underflow of the paleo–Pacific oceanic plate in late Paleozoic at a convergent margin of the South China Craton.

著者

Sota NIKI Kenta YOSHIDA Hikaru SAWADA Ryosuke OYANAGI Takafumi HIRATA

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.210814, 2022 (Released:2022-05-18)

参考文献数

24

被引用文献数

1

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Here we first report the in situ U–Pb dating of metamorphic grossular garnet (Grs) with distinction between internal zonation textures. The studied Grs occurs in an eclogite–facies marble collected from the eastern Iratsu body of the Sanbagawa metamorphic terrane, Japan. The Grs has a patchy texture, predominantly with pure Grs cores and andradite (Adr)–rich rims formed during eclogite–facies and exhumation stages, respectively. The U–Pb ages for the Grs core and Adr–rich rim were 97 ± 10 and 106 ± 16 Ma (95% confidence level), respectively. Despite the compositional zoning formed under different P–T conditions, the U–Pb ages of the core and rim were in similar values within analytical uncertainties. This decoupling of chemical zonation and U–Pb ages implies that the U–Pb chronological signatures of rims were inherited from cores owing to the redistribution of radiogenic Pb in cores during the rim formation through fluid–mediated dissolution and reprecipitation. The Grs U–Pb age (97 ± 10 Ma) thus directly corresponds to previously reported P–T conditions of the core formation during the eclogite–facies metamorphism. This advantage of Grt petrochronology as the combination of radiometric ages obtained by in situ analysis and P–T conditions deduced from paragenesis can contribute to reconstruct reliable metamorphic histories.

著者

Kenta YOSHIDA Sota NIKI Hikaru SAWADA Ryosuke OYANAGI

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.200730, (Released:2020-12-08)

被引用文献数

2

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Datolite [CaBSiO4(OH)] was discovered in an eclogite–facies calcite marble collected from the Eastern Iratsu body in the Sanbagawa metamorphic belt of central Shikoku. The marble was composed of calcite, diopside, and garnet that contained inclusions of omphacite. Enclosed in the marble is a pod composed mainly of quartz, with subordinate calcite, diopside, and garnet that has inclusions of datolite. The formation conditions of the datolite were estimated on the basis of mineral assemblage and the Raman elastic geobarometer to be approximately 400–650 °C and 0.8–1.3 GPa, which coincide with the conditions of the eclogite juxtaposition with the non–eclogite units in the Besshi district. Our study records the highest pressure–temperature conditions as the metamorphic datolite formation. Our findings provide evidence for the occurrence of B–rich fluid infiltration during the juxtaposition of eclogite unit with the non–eclogite unit in the Besshi district.

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

pp.230327, (Released:2023-10-13)

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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.

著者

Keisuke MITSU Tetsuo IRIFUNE Hiroaki OHFUJI Akihiro YAMADA

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.210319, (Released:2021-09-30)

被引用文献数

1

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Attempts to synthesize transparent polycrystalline jadeite have been made by direct conversion from bulk glass at pressures 10–20 GPa and temperatures 900–1300 °C using Kawai–type multianvil apparatus. The grain size of jadeite tends to decrease with increasing pressure, but we failed to synthesize polycrystalline jadeite with grain sizes in nano–regime (<100 nm) and obtained the sample with the smallest average grain size of ~ 240 nm at 20 GPa and 1300 °C for 20 min. Polycrystalline jadeite of the minimum grain size exhibits high optical transparency with a transmittance of ~ 70% for a typical wavelength in the visible region. The highest Vickers hardness (Hv) of 14.2 GPa was observed for the polycrystalline jadeite sample with the minimum grain size of ~240 nm, which is about 7% higher than the hardness (Hv = 13.3 GPa) of the sample with the largest grain size of ~ 390 nm. Further increases in optical transparency and hardness of polycrystalline jadeite would be realized if we get nano–polycrystalline samples by optimizing pressure, temperature, heating duration, etc. of the ultrahigh–pressure synthesis experiment.

著者

Raiki YAMADA Toshiro TAKAHASHI Yasuhiro OGITA

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.221219a, 2023 (Released:2023-11-24)

参考文献数

98

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Oligocene to Miocene volcanic rocks from the Toyama basin of the SW Japan arc, that were formed during back-arc spreading in the Japan Sea, were examined to reveal their petrogenesis and temporal change of arc volcanism during the Japan Sea opening. The arc volcanism in the Toyama basin initiated with rhyolitic pyroclastic flows (Tori Formation) containing hecatolite (moonstone) in 23-22 Ma. Enriched Sr-Nd isotope (SrI = 0.70769-0.70944; NdI = 0.51203-0.51224) suggests that contemporaneous andesitic magma (Kamiwazumi and Matsunagi Formations) mixed or assimilated basement granitoids and gneisses of the Hida belt to generate rhyolitic magma. Subsequently, andesitic volcanism (Iwaine Formation) occurred in 18-17 Ma after magmatic hiatus. Andesitic lavas of the Iwaine Formation are composed of high magnesian andesite (HMA), high-Sr andesite and tholeiitic andesite. HMA has Mg# > 64, high Cr and Ni concentrations, not so high Th/Yb and (La/Sm)N ratios, and slightly enriched Sr-Nd isotope (SrI = 0.70482; NdI = 0.51279). High-Sr andesite has relatively low SiO2 content (<60 wt%), high Sr (>2000 ppm) and K2O contents (3.98 wt% in the maximum), indicating that it is low-SiO2 adakite. These geochemical characteristics suggest that HMA and high-Sr andesite were produced by partial melting of the mantle wedge saturated by H2O derived from slab fluid and metasomatized by slab melt, respectively. Although chemical variation diagrams suggest tholeiitic andesite seems to have been generated from basaltic magma, it has enriched Sr-Nd isotope (SrI = 0.70713-0.70756; NdI = 0.51237-0.51241). Thus, tholeiitic andesite is considered to have been produced by AFC (assimilation and fractional crystallization) after generation of basaltic parental magma. Andesitic magmatism of the Iwaine Formation was followed by rhyolitic magmatism of the Iozen Formation in 17-16 Ma. The petrogenesis of the rhyolite from the Iozen Formation can be explained by low-rate mixing between andesitic magma (Iwaine Formation) and the Hida belt. The petrogeneses of the andesites, especially HMA and high-Sr andesite, are related to slab melting. Because the old and cold Pacific plate was subducting beneath the Toyama basin during the Japan Sea opening, additional heat source such as upwelling of the asthenospheric mantle into the mantle wedge is required. Moreover, back-arc spreading in the Japan Sea was driven by upwelling of the asthenospheric mantle into the mantle wedge.

著者

Risako HATADA Hidemi ISHIBASHI Yukiko SUWA Yusuke SUZUKI Natsumi HOKANISHI Atsushi YASUDA

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.190724, (Released:2020-06-26)

被引用文献数

1

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We conducted textural and chemical analyses of melt inclusions and their host plagioclase crystals in the scoria of the Izu–Omuroyama monogenetic volcano, erupted at ~ 4 ka in the Higashi–Izu monogenetic volcanic field, Japan. The groundmass melt was andesitic with ~ 59–61 wt% SiO2, and it contained abundant microphenocrysts of olivine and plagioclase. In contrast, ~ 59% of the plagioclase–hosted melt inclusions have rhyolitic compositions with ~ 70–75 wt% SiO2. The host plagioclase phenocrysts have cores with An# of 44.7 ± 4.2 [An# = 100Ca/(Ca + Na) in mol] and rims with An# of 68–78, and the calcic rims have compositions similar to the microphenocrysts. The cores of the host plagioclase phenocrysts have FeO* and K2O contents that are in equilibrium with the rhyolitic melt inclusions. Using the plagioclase–melt geohygrometers and assuming temperatures of 790–850 °C, we estimated the H2O contents of the rhyolitic melt inclusions to be ~ 4.4–10.2 wt%, indicating H2O–saturation depths of >4.5 km. Our results suggest that an inhibited reservoir of plagioclase–bearing rhyolitic melt existed beneath the monogenetic volcano at the time of the scoria eruption, which was ~ 800 years earlier than the first rhyolitic eruption in the volcanic field. Plagioclase content in the silicic reservoir is estimated to be less than 35.8%, suggesting the magma was eruptible. Our results demonstrate the potential usefulness of plagioclase–hosted melt inclusions for indicating the existence of such an inhibited silicic magma.

著者

Kazuya SHIMOOKA Satoshi SAITO Kenichiro TANI

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.230224, (Released:2023-07-28)

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We carried out zircon U-Pb dating of the Cretaceous gabbroic and granitic rocks exposed in the Kajishima to determine their magmatic ages. The plutonic rocks in the Kajishima are classified into seven lithologies: Hbl-bearing olivine norite, Type-1 Hbl-bearing troctolite, Type-2 Hbl-bearing troctolite, Type-1 pyroxene hornblende gabbronorite, and Type-2 pyroxene hornblende gabbronorite, massive granodiorite, and deformed granodiorite. The new zircon U-Pb ages are: 90.77 ± 0.99 Ma for the Type-2 Hbl-bearing troctolite, 92.35 ± 0.74 Ma for the Type-1 pyroxene hornblende gabbronorite, 91.33 ± 1.03 Ma for the massive granodiorite, and 84.11 ± 1.12 Ma for the deformed granodiorite. The new zircon U-Pb ages suggest multiple episodes of magmatic intrusion in Kajishima during ∼92 Ma and 84 Ma. Although two gabbroic rocks and a massive granodiorite show similar zircon U-Pb ages, subsequent granitic magmatism is unraveled in Kajishima, which is contrary to previous geological studies that postulated an evolution of all plutonic rocks from a single gabbroic parent magma.

著者

Keiko MORI Tatsuki TSUJIMORI Nelson BONIFACE

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.180713, (Released:2018-12-19)

被引用文献数

6

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We report a newly discovered assemblage of talc–kyanite in an amphibolite from the Isimani Suite of the Paleoproterozoic Usagaran Belt, central Tanzania. The amphibolite is characterized by the mineral assemblage of clinoamphibole, kyanite, talc with minor rutile, quartz, dolomite, and rare barite. The high Fe3+/(Fe3+ + Fe2+) ratio (0.48–0.80) of clinoamphibole and the presence of sulfate (barite) indicate a very–high oxidation state during metamorphism. P–T pseudosection modelling predicts that the studied talc– and kyanite–bearing amphibolites formed at high–pressure conditions (P > 1.0 GPa). Moreover, the modelling suggests formation of talc + kyanite + clinoamphibole at a highly oxidizing condition with CO2 fluid. This talc–kyanite association provides an index of high–pressure metamorphism of the Usagaran Belt and marks the oldest record of the talc–kyanite association in regional metamorphism in the Earth’s history.

著者

DAISUKE NISHIO–HAMANE TAKESHI YAJIMA ISSEI IKARI YOSHIYA OHKI HIROFUMI HORI YOSHIHIRO OHARA

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.230605, (Released:2023-09-07)

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Kiryuite and gunmaite were found as new minerals from Tsukubara, Kiryu City, Gunma Prefecture, Japan. Kiryuite is a Mn-rich analogue of viitaniemiite with an ideal formula of NaMnAl(PO4)F3 that mainly occurs as a white powder in cracks in triplite aggregate, and occasionally forms porous plate-like aggregates up to 5 mm in size, while the grains are several micrometers in size. In most cases, the aggregates are also accompanied by small amounts of other minerals such as goyazite, gorceixite, and fluorite. Kiryuite shows white streaks with a vitreous luster, and its Mohs hardness is estimated to be 5 by analogy with viitaniemiite. The calculated density is 3.32 g·cm-3 based on the empirical formula and unit cell volume refined from powder X-ray diffraction (XRD) data. The empirical formula for kiryuite calculated on the basis of O = 4 and F + OH = 3 is Na0.97(Mn0.56Ca0.38Fe0.04Mg0.02)Σ1.00Al0.98P1.02O4(F2.29OH0.71)Σ3. Kiryuite is monoclinic (P21/m) with a = 5.425(4) Å, b = 7.128(4) Å, c = 6.817(6) Å, β = 109.41(7)°, and V = 248.7(3) Å3 (Z = 2). The parameters [d in Å (I/I0) hkl] for the six strongest lines associated with kiryuite in the powder XRD pattern are 3.123 (57) 002, 2.923 (53) 012 and 120, 2.877 (100) 121, 2.560 (27) 200, 2.263 (43) 103, and 2.155 (76) 221. Gunmaite is a new alunite-related mineral with a new structure type that has an ideal formula of (Na2Sr)Sr2Al10(PO4)4F14(OH)12. Gunmaite mainly occurs as a core in hexagonal tablet crystals that coexist with gorceixite and goyazite-like minerals. Gunmaite is colorless and transparent with a greasy to resinous luster and is non-fluorescent. As a bulk crystal including gunmaite, the Mohs hardness is 5, cleavage is perfect on {001} planes, and the tenacity is brittle. The calculated density based on the empirical formula is 3.38 g·cm-3 using the empirical formula and single-crystal XRD data. The empirical formula for gunmaite calculated on the basis of O = 16 and F + OH = 26 is (Na1.72Sr0.70Mg0.56Ca0.01)Σ2.99(Sr1.32Ba0.68)Σ2(Al9.82Mg0.18)Σ10P3.99O16F16.21(OH)9.79. Gunmaite is trigonal (R3m) with a = 6.9972(2) Å, c = 50.270(2) Å, and V = 2131.51(13) Å3 (Z = 3). The structure consists of two PO4, AlO2(OH)4, AlF6, AlOF3(OH)2, SrO6(OH)6, and NaF8 polyhedra. Kiryuite and gunmaite are products of the final stage of hydrothermal activity in association with greisenization.

著者

Yasuhiro TAKAI Seiichiro UEHARA

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.2, pp.110-113, 2012 (Released:2012-05-03)

参考文献数

7

被引用文献数

3 5

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Rhabdophane-(Y), ideal formulaYPO4·H2O, occurs in a druse of the Higashimatsuura basalt at Hinodematsu, Genkai-cho, Saga Prefecture, Japan. It occurs as short rod-like crystals and forms radial aggregates. Rhabdophane-(Y) is hexagonal, P6222, a = 6.959(2) Å, c = 6.384(2) Å, V = 267.7(1) Å3, Z = 3. It is yellowish white to yellowish brown in color with a silky to dull luster. The density is 4.54 g/cm3 (calc.). The strongest lines in the X-ray powder diffraction pattern are [d (I/I0) hkl] 2.821 (100) 102, 3.013 (77) 200, 6.026 (76) 100, 4.385 (47) 101, 3.480 (44) 110, 2.127 (28) 003, and 1.854 (26) 212.

著者

Tatsuki TSUJIMORI

出版者

一般社団法人日本鉱物科学会

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.170406a, (Released:2017-09-30)

被引用文献数

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

Shumpei YOSHIMURA

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.221224a, 2023 (Released:2023-11-09)

参考文献数

39

被引用文献数

1

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H2O-CO2-dominated fluids play a crucial role in most geological phenomena involving fluid-mineral-melt interactions. The equation of state is an essential tool for understanding the phenomena because it predicts the thermodynamic properties of the fluids. The modified Lee-Kesler equation of state for H2O-CO2 mixture fluid developed by Duan and Zhang (2006) is the most accurate at present and is applicable to a wide pressure-temperature range (∼ 2573 K and ∼ 10 GPa). Because of its high accuracy and wide applicable range, the equation has been used for constructing solubility laws in silicate melts. In this paper I review the Duan and Zhang (2006) equation of state and present the calculation procedure. Because the equation for calculating the partial fugacity coefficient is erroneously presented in the original paper, the correct equation is provided here. A C-language code and a Windows executable program for computing thermodynamic properties are provided for the convenience of users. The influence of the nonideal behaviour of the H2O-CO2 mixture fluid on some geological situations is discussed.

著者

Daisuke NISHIO–HAMANE Katsuyuki SAITO

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.220309, 2022 (Released:2022-09-08)

参考文献数

38

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Mineralogical investigation of platinum–group minerals (PGM) from the placer deposit in northwestern Hokkaido, Japan, was conducted at six rivers and two coasts covering an area of 70 km north–south and 30 km east–west: the Moshosanbetsu River (M), the Shosanbetsu River (S), the Ainusawa River (A), the Tomamae coast (T), the Obira coast (OC), the Kamikinenbetsusawa River (K), the Obirashibe River (OR), and the Numatapon River (N) from north to south. Details of the major PGM grain and the occurrence of small but diverse PGM inclusions were revealed in this study. Among diverse PGM inclusions, Cu3Pt mineral was discovered in PGM placer from the coast of Tomamae town, and it has been approved as a new mineral, tomamaeite, named after the type locality, by the International Mineralogical Association, the Commission on New Minerals, Nomenclature and Classification (IMA–CNMNC). Later, tomamaeite was also discovered in five localities. Tomamaeite occurs in Pt–Fe(Cu) alloys such as tulameenite, ferronickelplatinum, tetraferroplatinum, and hongshiite as an anhedral particle with a size of less than 20 µm. Tomamaeite is an opaque mineral and has metallic luster with a pale mist white color in reflected light. The hardness of tomamaeite has yet to be determined, although it is estimated to be ~ 3½ from comparison with compositionally related minerals and the calculated density is 12.4 g·cm−3 using the empirical formula and powder X–ray diffraction data. The empirical formula of tomamaeite calculated on the basis of 4 apfu is (Cu3.01Fe0.06Ni0.01)Σ3.08(Pt0.90Ru0.01Rh<0.01Pd<0.01Os<0.01Ir<0.01)Σ0.93, (Cu2.92Fe0.05Ni0.04)Σ3.01(Pt0.97Pd0.01Rh0.01)Σ0.99, (Cu2.86Sb0.13Fe0.03Ni0.02)Σ3.03(Pt0.92Ir0.02Pd0.01Os0.01)Σ0.97, (Cu2.71Sb0.19Fe0.02Ni0.02)Σ2.94(Pt1.01Ir0.05)Σ1.06, (Cu2.93Fe0.02)Σ2.94(Pt1.04Rh0.01)Σ1.06, and (Cu2.82Fe0.04Ni0.04)Σ2.90(Pt1.07Ir0.03Pd<0.01)Σ1.10 from the Tomamae coast, the Moshosanbetsu River, the Shosanbetsu River, the Ainusawa River, the Kamikinenbetsusawa River, and the Numatapon River, respectively. Crystal chemistry was investigated using tomamaeite from the Tomamae coast. Tomamaeite is cubic, Pm3m, with lattice parameters a = 3.683(2) Å and V = 49.97(7) Å3 (Z = 1) of Cu3Au–type structure, in which Pt occupies the position of origin, and Cu occupies the face–centered positions on a face–centered cubic lattice. PGM from northwestern Hokkaido probably have a mostly common origin and are characterized by depleted ultramafic rocks, and tomamaeite is a non–unique mineral that is formed during the universal post–magmatic process with alteration of such ultramafic rocks to serpentine.

著者

Mariko NAGASHIMA Daisuke NISHIO–HAMANE Shuichi ITO Takahiro TANAKA

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.129-139, 2021 (Released:2021-07-17)

参考文献数

23

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Ferriprehnite (IMA2020–057), ideal formula Ca2Fe3+(AlSi3)O10(OH)2, is a new mineral that was found as secondary mineral in druses developed in the hydrothermal altered dolerite from Kouragahana, Shimane Peninsula, Japan. Ferriprehnite is an Fe analogue of prehnite. The crystals consisting of ferriprehnite and prehnite occur as a radial aggregate. The tabular crystals are up to 300 µm long, 100 µm wide, and 50 µm thick. Ferriprehnite is colorless to pale green with white streak and vitreous luster. It has a Mohs hardness of 6½. Its cleavage is good on {100}. The calculated density is 2.97 g/cm3. The empirical formula of ferriprehnite on the basis of 10O + 2OH using the result obtained by electron microprobe analysis is Ca1.99(Fe3+0.66Al0.34)Σ1.00(Al1.02Si2.98)Σ4.00O10(OH)2. Structure refinement converged to R1 = 4.64%. Its space group is orthorhombic Pma2 with unit–cell parameters a = 18.6149(10) Å, b = 5.4882(3) Å, c = 4.6735(3) Å, and V = 477.46(1) Å3. The determined site occupancy at the octahedral M site is Fe0.637(9)Al0.363 indicating that the M site is predominantly occupied by Fe. <M–O> increases with increasing Fe content leading to isotropic expansion of MO6 octahedra. The a– and c– dimensions of ferriprehnite are longer than those of prehnite due to Fe substitution for Al at the M site.

著者

Arashi KITAKAZE Hironori ITOH Ryuichi KOMATSU

出版者

一般社団法人日本鉱物科学会

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.106, no.4, pp.204-210, 2011 (Released:2011-09-21)

参考文献数

8

被引用文献数

3 6

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Horomanite and samaniite are found in the interstices among grains of silicate minerals in lherzolite from the Horoman peridotite massif, Samani-cho, Hokkaido, Japan. The mean analytical data for the horomanite, as determined by electron-probe micro-analysis (EPMA), are Cu: 0.43, Fe: 41.82, Ni: 23.76, Co: 0.52 and S: 33.29 for a total of 99.82 wt%. The empirical formula is (Fe5.77Ni3.12Co0.07Cu0.05)Σ9.01S8.00. Crystallographic data for the horomanite acquired by X-ray single-crystal (precession) and powder (Gandolfi) diffraction methods. They revealed a tetragonal symmetry, space group P4/mmm, a = 8.707 Å, c = 10.439 Å, V = 791.4 Å3, and Z = 4.The mean chemical composition of samaniite obtained by EPMA is Cu: 16.90, Fe: 34.60, Ni: 15.48, Co: 0.16, and S: 32.87 for a total of 100.01 wt%. The empirical formula is Cu2.08(Fe4.84Ni2.06Co0.02)Σ6.92S8.00. The crystallographic data for samaniite, which were obtained by X-ray single-crystal and powder-diffraction methods, are tetragonal symmetry, space group P42/mnm, a = 10.089, c = 10.402Å, V = 1058.9Å3, and Z = 4.

著者

Ichiro SUNAGAWA Yasushi TAKAHASHI Hiroyuki IMAI

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.102, no.3, pp.174-181, 2007 (Released:2007-07-03)

参考文献数

20

被引用文献数

35 37

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Alternating layers of calcite and aragonite, precipitated from mineral spring in fracture zones of serpentine mass, occur at Kashio, Oosika mura, Nagano Prefecture, Japan. Element mapping by means of Micro-area X-ray Fluorescence (MXRF) conclusively demonstrated that strontium concentrates more in aragonite layer, and not in calcite layer. Other elements including magnesium show no positive correlation with aragonite precipitation. MXRF analyses of aragonite samples from other localities and origins also indicated concentration of Sr as major impurity component, demonstrating that Sr plays essential role in metastable nucleation of aragonite in the precipitation of CaCO3 polymorphs from aqueous solution. This can be understood on the basis of modifications of surface energy term in CaCO3 nucleation in the presence of Sr. Temperature changes trigger to increase the Sr concentration in mineral spring, leading to metastable nucleation of aragonite.

著者

Tomohiro TAKEBAYASHI Yui KOUKETSU 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

pp.221219d, (Released:2023-07-28)

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Needle-shaped rutile inclusions occur in garnet within the quartz-eclogite at Mt. Gongen in the Sanbagawa belt, central Shikoku. They are approximately 5–25 µm along the long axis and are typically oriented along three directions, each intersecting at 120°. This indicates that the needle-shaped rutile is a lamella exsolved from the garnet. Garnet with needle-rutile inclusions is restricted to the quartz-poor domain of the quartz eclogite sample, which consist of quartz, garnet, omphacite, phengite, epidote, kyanite, and hornblende. Garnet grains with rutile lamellae show a composition of the almandine-pyrope series with 14–21 mol% grossular content. Rutile exsolution lamellae were concentrated in the range of 27–34 mol% pyrope of garnet crystals. The garnet host with rutile lamellae has a higher TiO2 content (TiO2 = 0.06–0.19 wt%) than those in rutile-free areas. These chemical compositional characteristics suggest that Ti was incorporated into the crystal structure during garnet growth and subsequently partially exsolved as rutile lamellae during the retrograde stage. Rutile lamellae in garnet have generally been regarded as indicators of ultrahigh-pressure metamorphism, but the present report from quartz-eclogite of the Sanbagawa belt, where no coesite has been found, provides evidence in a natural sample that the appearance of rutile exsolution lamellae is not necessarily under ultrahigh-pressure conditions.

著者

Mariko NAGASHIMA Yukina MORISHITA Yuji IMOTO Teruyoshi IMAOKA

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.200818, (Released:2021-02-10)

被引用文献数

1

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Mineral assemblages and chemical compositions of ore minerals from the Eboshi deposit, the historical Naganobori copper mine, Yamaguchi Prefecture, Japan were investigated in order to clarify its characteristics as a skarn deposit. Some Bi–, Ag–, and Te–bearing minerals are newly identified, which contribute updating the mineralization sequence of this deposit. Samples collected from the mine dump are one massive magnetite ore, and copper ores associated with skarn gangue minerals. Skarns are categorized as clinopyroxene skarn, garnet skarn, and wollastonite skarn, and the clinopyroxene skarn is the most dominant. The major ore minerals are chalcopyrite, cobaltite, and early–stage pyrite (Py–I) and later stage pyrite (Py–II). Py–II is enriched in arsenic (~ 5.19 As wt%). The Bi–, Ag–, and Te–bearing minerals, such as native bismuth, bismuthinite, wittichenite, emplectite, tsumoite, kawazulite, hessite, and matildite are minor ore minerals. Based on the mineral assemblages and textures of the specimens examined, four ore mineralization stages were recognized; the ore mineralization stage I is characterized by the major ore minerals such as chalcopyrite, bornite, pyrrhotite, sphalerite, and Py–I. The stage II is defined by the mineralization of cobaltite, Py–II, and Bi(–Cu)–bearing sulfides such as native bismuth, bismuthinite, and wittichenite. The mineralization stage III is characterized by the Ag– and/or Te–bearing ore minerals such as matildite, kawazulite, tsumoite, and hessite. The stage IV is characterized by chalcopyrite veins cutting the main skarn masses and the host limestone. The mineralogical properties and mineralization process of the Eboshi deposit is similar to those of the skarn deposits in the Yamato mine and the Tsumo mine, and consistent with common skarn–type deposits associated with ilmenite–series granitoids in the San–yo Belt, which are characterized by the occurrence of minor Ag– and/or Te–bearing ore minerals.