巻号一覧
73 巻, 8 号
選択された号の論文の3件中1～3を表示しています
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富樫 幸雄, 佐々木 昭, 寺島 滋1978 年 73 巻 8 号 p. 217-221
発行日: 1978/08/05
公開日: 2008/08/07
ジャーナル フリーThirteen purified pyrite specimens from the hydrothermally altered rocks of the Itaya kaolin clay mine, one of the largest paper-clay deposits in Japan, were examined for their sulfur isotope ratio and trace element content. Two generations of pyrite representing the two different stages of hydrothermal alteration in the deposits can be clearly distinguished with these data. Pyrites from the Miocene alteration zone developed in Miocene tuffs have fairly uniform δ 34S values around +5.5‰, while those from the Quaternary alteration zone in Pleistocene-Recent volcanic rocks yield the values with varying degrees of δ 32S enrichment, -3 to -10‰. As compared to the Quaternary samples, the Miocene pyrite specimens are characterized with much higher concentrations of such minor elements as Ag, As, Cu, Pb and Zn.
δ 34S data of the Miocene pyrites are close to the average sulfur isotopic composition for the Japanese Miocene mineralization represented by Kuroko deposits. The data of the Quaternary pyrites are found to be similar with the data reported for Quaternary volcanic sulfur in this country. A near-surface formative environment is assumed for the Quaternary alteration zone. This would cause a variable physico-chemical condition in the hydrothermal process, and in turn the variable isotopic trend in the Quaternary pyrites.抄録全体を表示PDF形式でダウンロード (283K) -
服部 勇1978 年 73 巻 8 号 p. 222-230
発行日: 1978/08/05
公開日: 2008/08/07
ジャーナル フリーTwo types of zeolite occurrences are recognized in the Paleozoic greenstones of the inner belt, central Japan.
One type is encountered within 1 km from the granitic plutonic bodies intruded into the Paleozoic strata. Zeolites of this type, composed of laumontite, stilbite, analcime, chabazite, thomsonite, and heulandite, occur as filling sharp and linear veins interesecting the amphibolite facies greenstones.
The other type of zeolite occurrence is developed in areas far from the plutonic bodies and generally occupies the areas of the lower grade of metamorphism than the pumpellyite-prehnite facies, probably of the zeolite facies. The zeolite minerals are mostly laumontite and occasionally analcime. They occur as filling irregular veins in lavas, as small aggregates in matrices or as strings along laminations of basic tuffs and tuffaceous shales.
The regional zoning of lower-grade metamorphic facies ranging from the greenschist facies to the zeolite facies has been made clear chiefly on the basis of mineralogical associations observed in the greenstones of Paleozoic age.抄録全体を表示PDF形式でダウンロード (524K) -
正路 徹也1978 年 73 巻 8 号 p. 231-246
発行日: 1978/08/05
公開日: 2008/08/07
ジャーナル フリーH20-CO2混合流体における方解石,鉄バスタム石(ferrobustamite),灰バンザクロ石,ヘデン輝石,磁鉄鉱,石英の相関係を,従来発表されているCaO-SiO2-CO2系およびCaO-FeOx-SiO2-O2系の研究結果をもとに考察した。灰バンザクロ石またはヘデン輝石を含むスカルンの生成に適した条件のCO2量の上限は,次の2つの反応,
(6)灰バンザクロ石+CO2=方解石+磁鉄鉱+石英+102
(8)ヘデン輝石+CQ2+O2=方解石+磁鉄鉱+石英
により決められる。灰バンザクロ石とヘデン輝石の安定領域から,これらの鉱物を含むスカルンを生成したH2O-CO2混合液体中のCO2量は,500℃で30mole%,300℃で0.5mole%を越えないと推定される。もし鉄バスタ云石が安定な場合には,この系の相関係はさらに複雑となる。しかし,上述した値はその安定性に無関係である。抄録全体を表示PDF形式でダウンロード (986K)
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