巻号一覧
28 巻 (1994)
- 6 号 p. 429-
- 5 号 p. 369-
- 4 号 p. 307-
- 3 号 p. 137-
- 2 号 p. 71-
- 1 号 p. 1-
28 巻, 4 号
選択された号の論文の8件中1～8を表示しています
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Katsuro Anazawa, Minoru Yoshida1994 年 28 巻 4 号 p. 307-315
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーMultivariate analysis was applied to the volatile content data obtained by Yoshida and his co-workers (e.g., Yoshida et al., 1971) to understand magma genesis in subduction zones. A statistical analysis was conducted by the methods of principal component analysis (PCA), factor analysis and hierarchical aggregative cluster analysis. The data can be interpreted on the basis of three principal components and three common factors. The first factor implies the contribution of seawater to magma genesis, which may take place through volatile release from the downgoing plate to the overlying upper mantle wedge. The second factor corresponds to the contribution of the mantle component with higher scores in volcanic rocks on the far side of the volcanic front. The third factor suggests the separation of FeS phase from silicate phase.抄録全体を表示PDF形式でダウンロード (1917K) -
Yoshikazu Sampei, Noriyuki Suzuki, Kazushi Mori, Tadashi Nakai, Kaichi ...1994 年 28 巻 4 号 p. 317-331
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーCompositional changes of phenanthrene (P) and methylphenanthrenes (MP) in mudstones received burial diagenesis and contact thermal alteration were examined to test their usefulness as thermal indicators. Mudstone samples were obtained from the MITI Takada-heiya well (Neogene Takada basin, Niigata, Japan) and from outcrops of the Kusanagi formation (Neogene, Yamagata, Japan), where the thermal alteration by dolerite intrusion occurred in Miocene time. Concentrations of MP increased in the sediments deeper than the peak of oil generation in both the MITI Takada-heiya well and the thermally altered Kusanagi shales. The main formation zone of MP seems to correspond to the relatively higher maturation stage (mean vitrinite reflectance: %Rm > 1.0; JNOC, 1988) and the wet gas generation zone. Relative abundances of 2- and 3-MP to P and/or other MP isomers (MPI1 by Radke et al., 1982a; MPI3 by Angelin et al., 1983) increased with increasing maturity in the oil and wet gas generation zone in both the MITI Takada-heiya well and the thermally altered shales. However, the MPI vs. %Rm relationships in burial diagenesis (the MITI Takada-heiya well) and in contact thermal alteration (Kusanagi shales) were different from each other. Markedly different heating rate and temperature may be the major reasons for the difference. In the overly matured zone from 2.0%Rm to 3.0%, MPI3 may indicate the apparent equilibrium for methyl-shift of MP.抄録全体を表示PDF形式でダウンロード (4074K) -
Katsuyuki Yamashita, Takeru Yanagi1994 年 28 巻 4 号 p. 333-339
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーU-Pb dating of zircons in a pelitic gneiss from the Oki metamorphic rocks gives an upper intercept age of 1.96 ± 0.04 Ga on the concordia diagram and an average Pb-Pb age of 1.96 ± 0.04 Ga. Rb-Sr biotite ages vary with crystal size and indicate that large biotite crystals are zoned in age. The relation between ages and crystal sizes reveals two different stages of crystallization. The age of the first stage was estimated to be about 180 Ma, which represents the time of the main phase of metamorphism. The second stage was estimated to have occurred at 161 ± 2 Ma, which represents the final phase of metamorphism. The U-Pb and Pb-Pb zircon ages represent the time of prominent plutonic activity in the provenance from which the clastic precursor of the pelitic gneiss was derived.抄録全体を表示PDF形式でダウンロード (1711K) -
Mariusz Orion Jedrysek, Michal Sachanbinski1994 年 28 巻 4 号 p. 341-350
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーCrust-form aragonite and needle-shape aragonite crystallized in cavities in magnesites as well as vein magnesite from ultramafic rocks related to the Sleza ophiolite (NE part of Bohemian Massif) have been examined for carbon and oxygen isotope ratios and for some trace elements. δ18OSMOW values of magnesite, corrected for acid-decomposition fractionation, comprise a narrow range of 23.7 to 27.9‰, which suggests near-surface temperature, high water-to-rock ratio, and meteoric origin of the ore-forming solution. This inference is further supported by δ13C values (–18.7 to –6.4‰) which indicate a biogenic origin of carbon. Moreover, chemical analyses of the magnesites showing lack of elements characteristic for intrusionrelated hydrothermal deposits support the meteoric-biogenic origin of the magnesite deposits of the Gogolow-Jordanow massif. The two types of aragonites are uniform in δ13C (–15.0 to –16.3‰) and δ18OSMOW (23.9 to 25.4‰). The Δ13Cmg-ar = –3.1 and –3.5‰ of two samples of magnesite-aragonite aggregates show the absence of carbon isotope equilibrium in this system. However, the Δ18Omg-ar = 4.0 and 1.8‰ for the respective samples suggest that the aragonites formed in the magnesites have possibly crystallized in oxygen isotope equilibrium with the host magnesite.抄録全体を表示PDF形式でダウンロード (2762K) -
Gunnar Jacks, Vidya P. Sharma, Peter Torssander, Göran Åber ...1994 年 28 巻 4 号 p. 351-358
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーGneisses and charnockites are major members of the bedrock of the southern-central part of the Indian peninsula. The charnockite is commonly weathered into Vertisols containing gypsum concretions in amounts commercially extractable. Sulphur in the concretions as well as sulphur in atmospheric deposition and in groundwater was investigated by means of sulphur isotopic analysis. The isotopic ratios in the gypsum fall in the same range as those in atmospheric deposition suggesting that the sulphate is of atmospheric origin brought in by the strong monsoonal winds. The deposition contains, along with the seawater sulphate, a reduced sulphur component possibly emanating from DMS or H2S from the Indian westcoast. The concretions are likely to be of a fossil character. The latest arid period on the peninsula occurred during the peak of the last glaciation which could be one possible period of accumulation. Another major sulphate source in the studied area is ammonium sulphate used as nitrogenous fertilizer. The mobilization of sulphur through bedrock weathering is negligible.抄録全体を表示PDF形式でダウンロード (1984K) -
Tsuyoshi Tanaka, Hikari Kamioka1994 年 28 巻 4 号 p. 359-362
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーTwenty-six elements in agate which is shaped into an agate mortar are examined. The agate contains impurities less than ppm level for most of the elements examined except for Na, K, and Fe. The elemental concentration levels are significantly low as compared with common crustal materials. Agate mortars are good enough to grind common crustal materials, but may give a little contamination for some elements when the element concentrations in samples are smaller than those in the agate.抄録全体を表示PDF形式でダウンロード (684K) -
Hikari Kamioka1994 年 28 巻 4 号 p. 363-366
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーNineteen elements were measured for a new GSJ rock reference sample, JR-3, by instrumental neutron activation analysis. It is found that JR-3 is much more abundant in large ion lithophiles such as rubidium, the rare earth elements, hafnium, tantalum, thorium and uranium than any other GSJ rock reference materials. No significant heterogeneity of the sample powder is detected for the amount of 60 mg level. Thus, JR-3 is especially useful as an analytical standard for those elements.抄録全体を表示PDF形式でダウンロード (1035K) -
Yutaka Kanai1994 年 28 巻 4 号 p. 367-368
発行日: 1994/08/20
公開日: 2008/04/08
ジャーナル フリーPDF形式でダウンロード (662K)
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