巻号一覧
47 巻 (2013)
- 4 号 p. 183-
- 3 号 p. 105-
- 2 号 p. 45-
- 1 号 p. 1-
47 巻, 4 号
選択された号の論文の7件中1～7を表示しています
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2012年度日本地球化学会賞受賞記念論文
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杉浦 直治2013 年 47 巻 4 号 p. 183-191
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーAccretion ages of meteorite parent bodies were estimated assuming homogeneous distribution of 26Al in the solar nebula. In case of iron meteorites, the accretion ages are constrained by the core formation ages (W isotopic composition of metal samples). In case of achondrites, Al-Mg and Mn-Cr ages obtained from (bulk) isochrons and/or Mg isotopic compositions of Al-poor meteorites could be used for constraining accretion ages. In case of chondrite parent bodies, the accretion ages are mainly constrained by the peak metamorphic temperatures. Formation ages of secondary minerals such as carbonates also constrain accretion ages of C chondrite parent bodies. Using literature data of bulk ε54Cr anomalies in meteorites and the estimated accretion ages, a diagram that suggests increase in ε54Cr with time of accretion is constructed. This is interpreted as a result of injection of 54Cr-rich grains into the solar nebula and the subsequent diffusive advection. Numerical simulations confirmed that the ε54Cr evolution obtained from meteoritic data can be well explained by an appropriate set of adjustable parameters (e.g. viscosity parameter=10-3 and injection radius〜100AU).抄録全体を表示PDF形式でダウンロード (981K)
2012年度日本地球化学会奨励賞受賞記念論文
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渋谷 岳造2013 年 47 巻 4 号 p. 193-207
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーMid-ocean ridges are places where interactions between seawater and oceanic crust take place. Hydrothermal interactions govern the chemistry of the oceans while hydrothermal vent fields host unique and diverse biological communities even in barren ocean floor settings, and are candidates for the birthplace of the earliest life forms. This paper presents the important roles of the hydrothermal carbonatization of Archean oceanic crust that is one of the characteristic seafloor alterations in the early Earth. Based on the mineralogical, geochemical, and geological features of calcite in the Archean greenstones, the CO2 flux from ocean to oceanic crust was estimated to be two orders of magnitude larger than the modern value, which points to the significance of seafloor hydrothermal carbonatization in the Archean carbon cycle. Furthermore, thermodynamic calculations of phase equilibria in the high-temperature alteration zone indicate that the hydrothermal fluid was alkaline due to the presence of calcite in the alteration minerals under a high-CO2 condition, and predict a generation of SiO2-rich and Fe-poor hydrothermal fluids in the subseafloor hydrothermal system. Such high-temperature alkaline fluids could have had a significant role not only in the early ocean geochemical processes but also in the early evolution of life.抄録全体を表示PDF形式でダウンロード (15809K)
企画総説「地球化学の最前線」
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天知 誠吾2013 年 47 巻 4 号 p. 209-219
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーIodine is one of essential trace elements for humans and animals, and is a constituent of thyroid hormones thyroxine and triiodothyronine. Insufficient iodine in the diet can cause iodine deficiency disorders such as endemic goiter and cretinism. Iodine has one stable isotope, 127I, and several radioisotopes, including 129I and 131I. From a radioecological viewpoint, long-lived 129I is of great concern because it is one of the most persistent radionuclides released into the environment from nuclear facilities and nuclear weapon testing. Given its long half-life (15.7 million years), 129I is expected to behave like a stable isotope over long time periods and it may accumulate in the human thyroid gland. Therefore, it is important to understand geochemistry of iodine for accurate safety assessments of 129I. The predominant chemical forms of iodine in the environment are iodate (IO3-; oxidation state, +5), iodide (I-; oxidation state, -1), and organically bound iodine. Recent studies have demonstrated that chemical forms of iodine are influenced or regulated by environmental organisms, especially bacteria. In this review, bacterially catalyzed iodine chemistries, including volatilization, accumulation, oxidation, reduction, sorption, and reductive dehalogenation of iodine, are summarized.抄録全体を表示PDF形式でダウンロード (4886K)
報文
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土岐 知弘, 比嘉 良作, 棚原 朗, 井尻 暁, 角皆 潤, 芦 寿一郎2013 年 47 巻 4 号 p. 221-236
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーWe used push corers during manned submersible dives to take sediment samples to depths up to 40cm from the third and eighth Kumano Knolls. Boron (B) concentrations in pore water extracted from the sediment samples from the cold seep site were higher than would be explained by organic matter decomposition, suggesting that the pore water at the site was influenced by B derived from smectite-illite alteration. Additionally, the pore water at the cold seep site on the Kumano mud volcano showed high Li concentrations and positive oxygen isotope of pore water. These facts suggest the origin of the pore water would be clay mineral dehydration occurring between 150-160℃. The end-member concentration of B and Li is estimated to be 23±8mmol/kg and 0.8±0.3mmol/kg, respectively. The B/Li ratio of the end-member is evaluated to be 29±14, suggesting these elements would be released from sediment below 200℃. Given the geothermal gradient in this area, this finding suggests that the supplied fluid originates from environment deeper than 3.5km below the seafloor.抄録全体を表示PDF形式でダウンロード (1568K) -
南 武志, 河野 摩耶, 古川 登, 高橋 和也, 武内 章記, 今津 節生2013 年 47 巻 4 号 p. 237-243
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーVermilion was collected from powerful people's mounds of places of Japan Sea coast depending on the period from the decline of the Yayoi to Kofun and was measured sulfur isotope ratio (δ34S value), and compared the value obtained from cinnabar ores of three Japanese mines, Niu, Yamato-suigin, and Sui, and two Chinese mines, Wanshan and Xunyang, which were selected from old records. The vermilion of the late Yayoi period, the 1st to 2nd century A.D., was from China, and the vermilion of the early Kofun period, from the late 3rd century A.D., was from Japan. During the late Yayoi and early Kofun periods, the 3rd century A.D., the vermilion showed the middle of the shift of Japanese cinnabar. It is concluded that the measurement of sulfur isotope of vermilion is an effective method for the determination of original sources of vermilion.抄録全体を表示PDF形式でダウンロード (852K)
博士論文抄録
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東田 盛善2013 年 47 巻 4 号 p. 244-245
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーPDF形式でダウンロード (332K) -
橋口 未奈子2013 年 47 巻 4 号 p. 246-
発行日: 2013/12/31
公開日: 2017/02/24
ジャーナル フリーPDF形式でダウンロード (209K)
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