巻号一覧
31 巻 (1997)
- 6 号 p. 345-
- 5 号 p. 263-
- 4 号 p. 189-
- 3 号 p. 125-
- 2 号 p. 63-
- 1 号 p. 1-
31 巻, 2 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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Masami Higashihara, Shun-ichiro Igari, Tatsuo Maekawa, Tetsuro Noda, S ...1997 年 31 巻 2 号 p. 63-73
発行日: 1997/04/20
公開日: 2008/04/08
ジャーナル フリーThree fumarolic gases, both gas and liquid phases, from the Kakkonda (Takinoue) geothermal area, northern Japan, were analyzed with a gas chromatograph-mass spectrometer to confirm the presence of C5+ hydrocarbons in the geothermal fluid of this area. C5+ hydrocarbons found in the analyses were mainly alkanes (C5-C15), aromatics (C6-C12) and cycloalkanes (C6-C8). Alkanes in the gas phase of one of the three samples show C10-C11 predominance, which has not been observed in other geothermal fields before. This clearly shows that compositions of heavier hydrocarbons from fumaroles in this area are not uniform. The variety suggests that up-flows in this geothermal circulation system take hydrocarbons with various degrees of thermal degradation up to the surface.抄録全体を表示PDF形式でダウンロード (2946K) -
Hiroshi Sakugawa, Isaac R. Kaplan1997 年 31 巻 2 号 p. 75-83
発行日: 1997/04/20
公開日: 2008/04/08
ジャーナル フリーMeasurements of 13C/12C, 18O/16O and 14C/12C ratios of CO collected at ground surface were performed, during July, 1992 through September, 1993, on twenty-five atmospheric samples which were obtained from Burbank, Lynwood and Westwood (Los Angeles), Lake Gregory and Ojai (semi-remote areas of southern California). The ranges of ambient CO concentrations were 0.4-3.9 ppmv and the isotopic ratios measured were -24.4 to -29.0‰ for δ13CV-PDB, and +16.3 to +24.9‰ for δ18OV-SMOW, respectively, while the content of modern carbon ranged from 20 to 68%. Although it is obvious that fossil fuel combustion (presumably from automobile exhaust) is the dominant source for CO in Los Angeles, domestic wood burning in winter or some other non-fossil fuel sources may contribute as much as 17% CO to the atmospheric burden in some areas of Los Angeles.抄録全体を表示PDF形式でダウンロード (2320K) -
Hodaka Kawahata, Naokazu Ahagon, Nobuhisa Eguchi1997 年 31 巻 2 号 p. 85-103
発行日: 1997/04/20
公開日: 2008/04/08
ジャーナル フリーThe carbonate content of two cores from the West Caroline Basin in the western equatorial Pacific was examined during the last 330 kyr. The results show that carbonate content varied greatly in core C4402, which was taken from a water depth of 4, 402 m between the present-day lysocline and the Carbonate Compensation Depth (CCD), whereas the content in core NGC34 which was recovered from a water depth of 2, 188 m, displays no distinct glacial-interglacial difference. The fluctuations observed in core C4402 are ascribed to dissolution induced by change in seawater chemistry rather than by changes in local rain rate of organic carbon. The degree and pattern of carbonate preservation in the West Caroline Basin differ from that observed in cores from the Ontong Java Plateau although both areas are within the western equatorial Pacific. The chronostratigraphy for cores C4402 and NGC34 is based on δ18O records to the SPECMAP stack record and on coccolithophorid stratigraphy. We chose δ18O records as the second variable in a cross-spectral analysis of δ18O versus the preservation degree. No significant differences were found even when we used a stacked δ18O record. Spectral comparison of carbonate preservation and δ18O records shows high coherencies at the 100-kyr and 41-kyr periodicities, but low coherency at the precessional period (23-kyr). We interpret the high coherencies as evidence that deep-water circulation changes, driven by high-latitude climatic forcing in the North Atlantic, are the principal source of variability in the carbonate preservation record of the West Caroline Basin. Carbonate preservation is in phase with δ18O at the 100-kyr period, indicating a rapid response of the dissolution intensity in Pacific deep and/or bottom water to changing climate.抄録全体を表示PDF形式でダウンロード (4573K) -
Takanori Nakano, Yukiko Ishikawa1997 年 31 巻 2 号 p. 105-118
発行日: 1997/04/20
公開日: 2008/04/08
ジャーナル フリーThree coarse-grained garnets from granitic pegmatites in the Ishikawa and Yamanoo areas, northeastern Japan, were traversed by an electron probe microanalyser (EPMA). Garnets occur in the feldspar zone (Ishikawa) and in the muscovite-feldspar-quartz zone (Yamanoo). The three garnet grains display distinct chemical zonings one another. One garnet from Ishikawa is unzoned. In another garnet from Ishikawa and one garnet from Yamanoo, Fe and Mg contents increase from core to rim as Mn content decreases. In the two zoned garnets, Ca content either monotonously increases to the rim or increases then decreases. These patterns were modeled by assuming varying values for partition coefficients, associated solid-phase compositions, and final proportions of garnet crystallized from the melt. The Ca peak is reproduced if partition coefficients change during the garnet growth and crystallization of a Ca-mineral such as feldspar removes Ca from the melt. The different zoning patterns in garnets within a single pegmatite zone are largely attributable to the difference in the growth rates of garnet and co-crystallizing minerals.抄録全体を表示PDF形式でダウンロード (3668K) -
Hodaka Kawahata, Minoru Kusakabe, Steven D. Scott1997 年 31 巻 2 号 p. 119-124
発行日: 1997/04/20
公開日: 2008/04/08
ジャーナル フリーPlagiogranites occur locally in the interface between the sheeted dike complex and the uppermost level of gabbros, containing a high proportion of sulfate with a δ34S value of 13.0‰ on average. Strontium and sulfur isotopic compositions of the plagiogranites suggest that magmatic or magmatic-hydrothermal sulfate constitutes the major fraction of the sulfate in the plagiogranites with high δ34S values and that seawater-derived Sr might have been incorporated in the latest stage of crystallization.抄録全体を表示PDF形式でダウンロード (1826K)
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