巻号一覧
37 巻 (2003)
- 6 号 p. 639-
- 5 号 p. 537-
- 4 号 p. 413-
- 3 号 p. 299-
- 2 号 p. 145-
- 1 号 p. 1-
37 巻, 6 号
選択された号の論文の5件中1～5を表示しています
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Jisun Park, Ryuji Okazaki, Minoru Kusakabe, Keisuke Nagao, Shigekazu Y ...2003 年 37 巻 6 号 p. 639-648
発行日: 2003/12/20
公開日: 2008/04/08
ジャーナル フリーNoble gas and oxygen isotopic compositions were studied for the Towada meteorite, a recent fall in Aomori Prefecture, Japan. The meteorite was classified as a H6 chondrite based on oxygen isotope ratios (δ17O = 2.82‰, δ18O = 4.03‰) and concentrations and elemental ratios of the heavy noble gases. The U, Th-He and K-Ar gas retention ages, calculated as 0.38 b.y. and 1.3 b.y., respectively, suggest preferential loss of 4He compared with 40Ar. Cosmic-ray exposure ages using cosmogenic 3He, 21Ne and 38Ar concentrations were 7.67, 31.1 and 18.6 m.y., respectively. The 3He and 4He loss observed for this meteorite may be due to heating by solar radiation during orbital motion around the Sun. The short nominal exposure age based on 38Ar may be due to 38Ar loss during weathering or due to chemical heterogeneity of the meteorite. Existence of excess fissiogenic 131-136Xe from extinct 244Pu is consistent with the presence of 129Xe produced from extinct 129I.抄録全体を表示PDF形式でダウンロード (2461K) -
Yuzo Yoshiike2003 年 37 巻 6 号 p. 649-662
発行日: 2003/12/20
公開日: 2008/04/08
ジャーナル フリーA change in the chemical composition of Obuki Spring, a typical chloride-sulfate acid hot spring in Japan, has been revealed by continuous observation for more than 40 years. The concentration of SO42- increased markedly from 1972 (∼1 g/l) to 1978 (∼3 g/l), then decreased gradually from 1978 to 1990 (∼1 g/l). Variations in the Cl- concentration were apparently within a smaller range than those of the SO42- concentration. The concentrations of numerous cations increased during 1972–1990, as did the SO42- concentrations. This variation is thought to be the result of a mechanism involving a second source, namely, volcanic emanations of a sulfur-rich composition, which were temporarily added to emanations from the first source; the first source has continuously supplied volcanic emanations to the original acid hydrothermal solution at Obuki Spring, and the second source is responsible for the increase in SO42-, Cl-, and acidity. Variations in the concentrations of most other components can be explained as the result of changes in the interaction between the acid hydrothermal solution and the surrounding rocks; the latter changes were themselves the consequence of increases in acidity.抄録全体を表示PDF形式でダウンロード (603K) -
Sachio Kobayashi, Hajime Imai, Hisayoshi Yurimoto2003 年 37 巻 6 号 p. 663-669
発行日: 2003/12/20
公開日: 2008/04/08
ジャーナル フリーAn enrichment of oxygen-16 of about 8% relative to the Earth has been found in a chondrule from the Acfer 214 carbonaceous chondrite. In contrast, isotopic abundances of major cations, Mg and Si, are similar to those of the Earth. These suggest that oxygen isotopic heterogeneity in the early solar system was much larger ever thought and assist mass-independent-isotopic fractionation for the origin. Because the chondrule has solar abundance for refractory and normal lithophile elements, we propose that silicate dusts in the early solar system were initially enriched in 16O corresponding to the 16O-rich reservoir.抄録全体を表示PDF形式でダウンロード (789K) -
Tsuyoshi Ishikawa, Kenji Sugimoto, Kazuya Nagaishi2003 年 37 巻 6 号 p. 671-680
発行日: 2003/12/20
公開日: 2008/04/08
ジャーナル フリーAn analytical technique of rare-earth elements (REE) in rock samples using a high-performance ion chromatography (HPIC) is described. The REE in rock samples were separated from other elements using a conventional ion-exchange column, and then measured by the HPIC. α-hydroxyisobutyric acid and Arsenazo III were used for eluants and a post-column reagent for the HPIC, respectively. The use of a high-resolution HPIC column enabled to analyze all fourteen REE without any interference from Y and other transition metals. The REE concentrations determined for twelve Geological Survey of Japan rock reference samples, having varied major element compositions, showed good agreement with the recommended values and the values recently obtained by inductively coupled plasma-mass spectrometry (ICP-MS). This HPIC technique provides an inexpensive means to obtain high-quality data of all fourteen REE in rock samples as small as <50 mg, and potential for wide geochemical applications as an alternative to ICP-MS.抄録全体を表示PDF形式でダウンロード (245K) -
Yoji Arakawa, Xiaolin Li, Mitsuru Ebihara, Engin Meriç, Izavel ...2003 年 37 巻 6 号 p. 681-693
発行日: 2003/12/20
公開日: 2008/04/08
ジャーナル フリーSome element concentrations were measured and element profiles were made for the Cretaceous-Tertiary (K-T) boundary layers in Medetli, Gölpazari, northwestern Turkey. In Medetli region, gray-colored medium to coarse grained sandstone (layer A) is overlain by yellow-colored fine-grained sandstone with intercalated thin goethite-rich layers (layer B). White colored limestone (layer C) overlies on the layer B. The layer A is latest Cretaceous and layer C is early Paleocene, and in layer B (28–37 cm in thickness) fossils are absent, and is regarded as a K-T transitional layer. In several goethite-rich layers, siderophile elements such as Fe, Cr, Ni, Co, and chalcophile element, such as As, Sb, and Zn, are enriched, and have maximum in succession from layer A to C. The enrichment of these elements are common features in most of K-T boundary sediments of the world. However, Ir concentration is relatively low (0.05–0.10 ppb) in the goethite-rich layers. The analyzed Ir concentration is slightly elevated (0.24 ppb) only in the top part of layer A. Iridium may have been diluted during sedimentation and diagenesis. The actual K-T boundary may be situated between the top of layer A and the bottom of layer B. The section from the top part of layer A to layer B is assumed to have been formed during the K-T and its successive events.抄録全体を表示PDF形式でダウンロード (1000K)
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