著者

鉱物科学に関する用語検討委員会

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.6, pp.345-346, 2015 (Released:2016-01-09)

---

「直方晶系(斜方晶系)」への対応 鉱物科学に関する用語検討委員会

著者

大西 政之

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.1, pp.25-27, 2009 (Released:2009-03-20)

参考文献数

21

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.49, no.1, pp.35-37, 2020 (Released:2020-05-02)

---

日本新産鉱物情報(2018年)以降,2019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

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

pp.170618, (Released:2017-12-07)

---

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

小原 泰彦

出版者

日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.41, no.5, pp.193-202, 2012-09-30

被引用文献数

1 5

---

The Godzilla Megamullion is the largest known oceanic core complex, located in the Parece Vela Basin, an extinct backarc basin in the Philippine Sea. The previous studies argued that the basin was active from 26 Ma to 12 Ma at an intermediate-spreading rate of 8.8-7.0 cm/year full-rate, although the basin shows the characteristics typical for slower spreading ridges. For example, many peridotites in the Parece Vela Basin are much less depleted than those exposed at comparable spreading rates on other mid-ocean ridge systems. The tectono-magmatic characteristics of the Parece Vela Basin were thus thought unusual and paradoxical.<br>   However, the recent studies, based on the high-density samplings on the Godzilla Megamullion, show the evidences that the basin became slow to ultraslow environment in its terminal phase. Zircon U-Pb dating of gabbroic rocks from the Godzilla Megamullion reveals that the estimated slip rate of the Godzilla Megamullion detachment fault was ∼ 2.5 cm/y; significantly slower than the previous estimate. The morphology and geology of the termination area are similar to those observed in ultraslow-spreading ridges. Decreasing degree of partial melting of the peridotites as well as increased amount of plagioclase-bearing peridotites (showing melt stagnation in the shallow lithospheric mantle) are observed towards the termination of the Godzilla Megamullion.<br>   Based on the recent observations at the Godzilla Megamullion, it would be argued that the terminal phase of a backarc basin development will go through an ultraslow-spreading environment, erupting alkaline basalts. There will be an overlap period of the terminal alkaline basalt magmatism and the rifting of a succeeding backarc basin.<br>

著者

坂野 靖行

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.230516, (Released:2023-08-08)

---

Monazite in a granite pegmatite from Yamanoo, Sakuragawa, Ibaraki Prefecture, Japan has been examined in terms of U, Th, Pb, and rare earth element (REE) chemistry by electron microprobe analysis. This pegmatite occurs as a lenticular vein in the Kabasan granitic body. Oscillatory and sector zoning were observed by back-scattered electron images. An averaged empirical formula was (Ce0.286Nd0.180Sm0.104La0.077Y0.069Pr0.041Gd0.069Dy0.020Er0.004Th0.069U0.011Ca0.052)Σ0.982 (P0.983Si0.027)Σ1.010O4. Compositional variations suggest that the (Th + U) contents are controlled mainly by the coupled substitution (Th, U) + Ca = 2REE. Calculated U-Th-Pb chemical ages based on the assumption that the initial Pb is negligible are 61 ± 11–69 ± 10 Ma (2σ) and consistent with previously reported radiometric ages for the Kabasan granitic body.

著者

小澤 一仁 永原 裕子

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.42, no.3, pp.136-155, 2013 (Released:2013-07-02)

参考文献数

145

被引用文献数

1 3

---

Approaches to elucidate thermal history of the earth based on information of earth materials are reviewed. Limitations of these approaches are examined, and ways for the improvement and additional approaches to better constrain the thermal history of the earth are proposed. A short note of the current thermal status of the earth is followed by examination of earth's thermal history based on geophysical modeling of mantle convection, combination of which with material information is essential to deepen our understanding. There are several proxies of earth materials for secular changes of the thermal state of the earth's interior. Those often used so far are: (1) chemical composition of magmas, from which ‘potential temperatures’ of the ambient mantle are estimated, (2) pressure and temperature conditions of crustal materials (metamorphic rocks), from which ‘metamorphic geothermal gradients’ are estimated, (3) thickness of the crust and lithosphere, from which thermal gradients of the crust and lithosphere are estimated along with the temperature estimation of the bottoms, and (4) pressure and temperature of mantle materials, from which ‘mantle geothermal gradients’ of the lithosphere are estimated. Each method has problems to be resolved for quantitative estimation of the secular variation of the earth's thermal state. The following approaches are proposed: (1) coupling thickness of oceanic crust and depletion zone of residual mantle and major element composition of volcanic rocks, (2) high-resolution analysis of thermal history of crust and mantle materials to better constrain steady-state geotherms, and (3) simultaneous estimation of ambient pressure and temperature as well as mantle potential temperature from analysis of magma intrusions in the crust. Finally, the importance of extraterrestrial materials and earth-like exoplanets to reveal thermal history of the early earth, for which direct information is not available, is remarked.

著者

纐纈 佑衣

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.230110a, (Released:2023-04-13)

---

Spectroscopy has been widely used in geology since the 1990s because it is non-destructive and easy to analyze. Raman spectroscopy has generally been used to identify mineral phases in geology, but recent studies have proposed new methods to quantitatively estimate the metamorphic pressure (quartz Raman barometry) and peak temperature (Raman carbonaceous material geothermometry). Studies using infrared spectroscopy are also underway to advance our understanding of hydration processes in subduction zones and mantle through the analysis of water in rocks. In addition to the development of new methods using spectroscopy, new tools are also being developed to analyze huge amounts of data through iterative processing, which will enable the extraction of more informative and quantitative results in a shorter time. This paper introduces examples of spectroscopy applications in geology and examines future developments.

著者

高井 康宏

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.1, pp.51-53, 2019 (Released:2019-03-28)

参考文献数

8

著者

松本 啓作 平島 崇男

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.35, no.2, pp.97-108, 2006 (Released:2006-04-10)

参考文献数

6

被引用文献数

4 4

---

We propose a new modal analysis method using a scanning electron probe microanalyzer with an energy dispersive X-ray analytical system. The procedure is based on the multipoint analysis software of EDAX® Inc. The analysis points are selected as equal interval grids in the secondary electron image (SEI), which covers 3.2 × 2.45 mm2 area as the maximum. The mineral identification of each X-ray spectrum can be done by the combination of the assemblage and content of mineral forming elements. This method can identify most of rock-forming minerals easily, what is an advantage comparing with the conventional modal analysis method under the optical microscope. To obtain the reliable modal data, we can adjust grid intervals depending on the grain size of rock forming minerals and the numbers of the beam acquisition areas depending on the degree of heterogeneity of samples. This technique is available for the rock sample with average grain size between 0.2 and 2.0 mm by the restriction of the minimum enlargement size of the SEI. The new method gives the concordant modal data to those obtained by the conventional point-counting method by several beam acquisition areas for homogeneous samples and by a few tens beam acquisition areas for heterogeneous samples.

著者

西川 治

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.230127, (Released:2023-04-08)

---

秋田大学大学院国際資源学研究科附属鉱業博物館 ─岩鉱分野の展示の見どころ─

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

pp.220217, (Released:2022-03-08)

---

日本新産鉱物情報(2020年)以降,2021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

角縁 進 永尾 隆志 長尾 敬介

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.5, pp.191-198, 2000 (Released:2008-08-30)

参考文献数

41

被引用文献数

15 16

---

More than 40 monogenetic volcanoes are distributed over an area of 400 km2 in the Abu Monogenetic Volcanic Field, southwest Japan. The eruptive products consist of alkaline basalt and calc-alkaline andesite to dacite lavas and pyroclastics, which are collectively known as the Abu Monogenetic Volcano Group. We have examined the eruption history of the Abu Monogenetic Volcano Group based on 33 new K-Ar ages. Most samples were dated by normal K-Ar method, and yielded ages between 1.9 and 0.1 Ma. The ages of two very young samples were determined using an unspiked method incorporating a mass-fractionation correction procedure. This gave an averaged age of about 40 ka. K-Ar ages from the Abu Monogenetic Volcano Group are concentrated at around 1.7 Ma and 0.2 Ma, and the activity is therefore classified into early and late periods, respectively. The early activity had a duration of about 0.4 mys, during which time 0.3 km3 of alkaline basalt alone was erupted. The late activity produced 0.8 km3 of alkaline basalt and 2.1 km3 calc-alkaline andesite to dacite, and lasted about 0.8 mys. Alkaline basalt was mostly produced in the first half of the late period, with maximum eruption rate at about 0.4 Ma. This activity was followed by more voluminous calc-alkaline andesite-dacite eruptions which climaxed at 0.2 Ma. Although associated alkaline basalt activity continued in this period, eruption volumes steadily decreased. Periodic alkaline basalt activity in southwest Japan is thought to have originated from small mantle diapirs, with intermediate calc-alkaline magmas being produced by mixing between alkaline basalt and felsic crustal melts. Coincidence of alkalic and calc-alkaline magmas and the eruption history in the later period in the Abu Monogenetic Volcano Group suggest that heating induced by repeated intrusion of alkaline basalt resulted in partial melting of the lower crust, thus producing intermediate to felsic calc-alkaline magmas. These crustal melts may then have mixed with alkaline basalt and produced the relatively voluminous intermediate calc-alkaline magmas erupted in the latest stage.

著者

三河内 岳

出版者

一般社団法人 日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.51, no.1, pp.220214, 2022 (Released:2022-04-30)

参考文献数

89

被引用文献数

1

---

For the past 30 years, I have performed a mineralogical study of various kinds of extraterrestrial materials focusing on evolution processes of Solar System bodies. The samples analyzed range from primitive chondritic materials returned by spacecrafts to differentiated meteorites including Martian and lunar samples. The first of these analyzed meteorites was an angrite, one of the oldest known achondrites, in collaboration with researchers at NASA's Johnson Space Center, USA. I pointed out the importance of olivine xenocrysts by studying many quenched angrites and showed that bulk compositions of quenched angrites were controlled by resorption degrees of these xenocrysts. Soon I became involved in studying Martian meteorites. In my early works, I found that some shergottite Martian meteorites experienced undercooling of magma and represented parent magma compositions by combining crystallization experimental results. I also revealed that nakhlite Martian meteorites had correlated petrography and mineralogy that could be explained by crystallization at different locations (burial depths) in a common cooling cumulate pile. The presence of remarkable shock features (e.g., darkening of olivine) in Martian meteorites is striking, and it appears that prolonged post-shock heating history largely erased the high-pressure polymorphs in many cases. My research deals with primitive solar system materials including Wild 2 cometary particles and Itokawa asteroidal particles. Studying these samples using electron beam and synchrotron radiation analyses has strengthened the interpretations of their origins. Another important tool employed is electron backscatter diffraction (EBSD) analysis. I applied this technique to identify several new minerals such as dmitryivanovite, andreyivanovite, and kushiroite in early 2000s. EBSD was also used to analyze preferred crystallographic orientation of olivine in brachinites, revealing rigorous magmatic and/or rheological activities in the parent body. At present I am analyzing Ryugu samples returned by the Hayabusa2 spacecraft as a preliminary analysis team member, which broadens our understanding of the formation and evolution processes of solid materials in the early Solar System.

著者

宮島 宏

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.36, no.6, pp.184-186, 2007 (Released:2008-03-27)

著者

石川 晃

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.41, no.5, pp.203-210, 2012 (Released:2012-11-30)

参考文献数

53

被引用文献数

1

---

Three enigmas of highly siderophile elements (HSE) in Earth's mantle, manifested by recent advances in HSE geochemistry of mantle peridotites, are reviewed in this paper. They are (1) the apparent overabundance of the HSE in the Earth's mantle compared to metal-silicate equilibrium, (2) supra-chondritic Pd/Ir and Ru/Ir ratios in primitive upper mantle (PUM) estimates, and (3) contrasting HSE patterns between massif- and xenolithic-peridotites. More studies on both natural and experiment-based data are clearly required for resolving these problems.

著者

花室 孝広 梅田 浩司 高島 勲 根岸 義光

出版者

日本鉱物科学会

雑誌

岩石鉱物科学 (ISSN:1345630X)

巻号頁・発行日

vol.37, no.2, pp.27-38, 2008-03-30

被引用文献数

1 2

---

The high temperature hot springs such as in Yunomine and Tosenji and the hydrothermal alteration zones of the Hongu area are distributed in the southern part of Kii peninsula, though Quaternary volcanoes which can be their potential heat sources are not distributed in the area. This research has aimed to understand the thermal history of the area by using several dating methods.<br>     Thermoluminescence (TL) dating method was applied according to the distance from dykes or gushing out point of the hot springs which thought to be the center of alteration. The results show that the alteration age of Yunomine alteration zone is younger as it approaches the gushing out point of hot spring. No clear tendency was observed in other places. These results suggest that the alteration ages near Yunomine hot spring are controlled by the distance from the gushing out point. However, no clear tendency was observed at other hot springs between the alteration ages and the distance from the center of alteration when two or more activities of alteration have occurred.<br>     The results of the TL, Fission Track (FT) and K-Ar dating show that after the high temperature hydrothermal alteration (until tens of millions of years ago), relatively low temperature alteration (from at least hundreds of thousands of to tens of thousands of years ago) occurred in Hongu and Totsukawa area.

著者

土谷 信高 武田 朋代 足立 達朗 中野 伸彦 小山内 康人 足立 佳子

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.2, pp.69-90, 2015 (Released:2015-05-02)

参考文献数

89

被引用文献数

4 14

---

Early Cretaceous igneous rocks in the Kitakami Mountains consist of volcanic rocks, dike rocks, and plutonic rocks, from older to younger. Plutonic rocks are composed mainly of adakitic granites in central part of zoned plutonic bodies surrounded by adakitic to non-adakitic granites in marginal part. These adakitic plutons is divided into E and W zones based on the ages and geochemistry. Zircon U-Pb ages were determined with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 22 samples from 13 rock bodies including the Early Cretaceous adakitic granites in the Kitakami Mountains. Zircons from the adakitic granites of E zone give older ages (127-117 Ma) compared with those of W zone (119-113 Ma). Zircon ages of the calc-alkaline to shoshonitic rocks and dike rocks range from 128-124 Ma, which are similar to the oldest rocks of the E zone (127-125 Ma). Zircon ages become younger from the northern Hashikami pluton and marginal facies of the Tanohata pluton (127-125 Ma) to southern Takase granites (118-117 Ma), in the E zone adakitic granites. Petrochemical differences between the E zone and W zone rocks indicate that the adakitic melt of E zone rocks are considered to be derived from vapor-absent melting condition, while those of W zone rocks are from higher pressure and vapor-present condition.   Taking all these data into consideration, the Early Cretaceous magmatisms in Kitakami can be explained by the differential subduction model of the Farallon-Izanagi plates or slab rollback model accompanied with asthenospheric upwelling.

著者

清水 以知子

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.39, no.6, pp.208-219, 2010 (Released:2011-01-29)

参考文献数

81

被引用文献数

1

---

The connectivity of grain-edge fluid channels in the lower crust and mantle is controlled mainly by the solid-liquid dihedral angle. To explain the change in equilibrium dihedral angle at elevated temperature and pressure, as observed in laboratory experiments, we developed two kinds of statistical thermodynamic models: a lattice-like model based on the Gibbs theory of adsorption, and a model based on the Cahn-Hilliard theory of non-uniform systems. The models perform well in explaining experimental data on dihedral angles in the forsterite-H2O system. The complicated temperature dependence of dihedral angle in the quartz-H2O system is possibly explained by the occurrence of multilayered adsorption.

著者

花室 孝広 梅田 浩司 高島 勲 根岸 義光

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.37, no.2, pp.27-38, 2008 (Released:2008-05-15)

参考文献数

53

被引用文献数

1 2

---

The high temperature hot springs such as in Yunomine and Tosenji and the hydrothermal alteration zones of the Hongu area are distributed in the southern part of Kii peninsula, though Quaternary volcanoes which can be their potential heat sources are not distributed in the area. This research has aimed to understand the thermal history of the area by using several dating methods.     Thermoluminescence (TL) dating method was applied according to the distance from dykes or gushing out point of the hot springs which thought to be the center of alteration. The results show that the alteration age of Yunomine alteration zone is younger as it approaches the gushing out point of hot spring. No clear tendency was observed in other places. These results suggest that the alteration ages near Yunomine hot spring are controlled by the distance from the gushing out point. However, no clear tendency was observed at other hot springs between the alteration ages and the distance from the center of alteration when two or more activities of alteration have occurred.     The results of the TL, Fission Track (FT) and K-Ar dating show that after the high temperature hydrothermal alteration (until tens of millions of years ago), relatively low temperature alteration (from at least hundreds of thousands of to tens of thousands of years ago) occurred in Hongu and Totsukawa area.