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-
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37 巻, 3 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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Naoto Takahata, Reika Yokochi, Yoshiro Nishio, Yuji Sano2003 年 37 巻 3 号 p. 299-310
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーTwenty three gas samples were collected from hot and mineral springs associated with Ontake volcano in central Honshu, Japan from June 1996 to June 2000. The chemical compositions, He, Ar, C and N isotopic ratios were measured using a gas chromatography, noble gas and stable isotope mass spectrometers, respectively. The 3He/4He ratio decreased with increasing distance from the central cone of the volcano to the sampling site, while δ13C value of CO2 increased with the distance. Such trends are consistent with those observed from November 1981 to June 1993 in the literature, suggesting that source of magmatic helium and carbon is located beneath the volcanic cone and they are continuously emitted into surroundings. The δ15N value of N2 increased with the distance while most 40Ar/36Ar ratios were similar to the atmospheric value. Magmatic nitrogen may also be carried by a fluid flowing through the volcanic edifice and diluted by crustal nitrogen. Significant increase of 3He/4He ratio from 1996 to 2000 was observed at the site close to the fault formed by a M6.8 earthquake that occurred in September 1984, which agrees well with the 3He/4He change from November 1981 to June 1993. Anomalous increase of δ13C value was observed at Shirakawa site from June 1993 to June 2000. The change cannot be explained by a simple two-component mixing between magmatic and crustal end-members and may require another model with three end-members, mantle, limestone and sediment.抄録全体を表示PDF形式でダウンロード (710K) -
Bin Xia, Heng-Xiang Yu, Gen-Wen Chen, Liang Qi, Tai-Ping Zhao, Mei-Fu ...2003 年 37 巻 3 号 p. 311-324
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーThe Cretaceous Dagzhuka ophiolite lies in the middle segment of the Yarlung-Zangbo suture zone, Tibet, and has a well-preserved ophiolitic section including a mantle sequence, cumulate complex, diabase dyke swarm and basaltic lavas. Compared to the primitive mantle, tectonized peridotites in the Dagzhuka ophiolite are depleted in Al, Ca, Ti and high field strength elements, but relatively enriched in large ion lithophile elements (Rb, Ba, Th). They have U-shaped, chondrite-normalized REE patterns suggesting an early stage of depletion by partial melting, followed by enrichment from slab-derived fluids. These features support a model in which the mantle peridotites at Dagzhuka formed in a forearc setting. The diabases and basalts are low-K tholeiites depleted in LREE, with compositions similar to N-MORB. However, these rocks are strongly depleted in Nb and Ta but enriched in Th and Rb, features characteristic of island arc lavas. Thus, the Dagzhuka ophiolite is believed to have formed in a supra-subduction zone environment, possibly a fore-arc basin.抄録全体を表示PDF形式でダウンロード (700K) -
H. Meier, E. Zimmerhackl, G. Zeitler2003 年 37 巻 3 号 p. 325-350
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーResults are presented which have been obtained in prediction studies on the colloid-associated transport of radionuclides through porous groundwater aquifers overlying as geochemical barrier the planned nuclear repository site at Gorleben, Germany. The studies incorporate three-phase retardation factors for 227Ac, 228Th, 232U and 210Pb in site-specific groundwater aquifers containing humic colloids and efficiencies for Brownian deposition of colloidal carriers onto immobile sedimentary grains. It is shown that colloid-bound radionuclide migration can be approximately modeled by using the basic advection-dispersion transport equation modified with three-phase retardation coefficients and colloid-chemical attachment factors due to the presence of multiple phases, i.e., fluid, colloid and immobile solid. Moreover, results of site-specific assessment studies indicate that the transport of colloid-associated radionuclides in porous groundwater aquifers overlying the Gorleben salt dome may not occur over long distances, provided that the nuclides are transported by porous flow only.抄録全体を表示PDF形式でダウンロード (370K) -
Giampiero Venturelli, Tiziano Boschetti, Vittorio Duchi2003 年 37 巻 3 号 p. 351-366
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーNa-carbonate (NaCW) waters are not concentrated in well defined areas, but usually widespread in areas where other water types (e.g., Ca-carbonate) are dominant. NaCW are the product of long-term water-rock interaction with dissolution of Na-silicates in presence of phyllosilicates, silica phases, and calcite. NaCW circulating in calcite-bearing sediments very probably have a Ca-carbonate parent with moderate to low PCO2, which changes its composition assuming increasing Na character as the water-rock interaction proceeds. However, the moderate to low PCO2 values of the potential parent Ca-carbonate waters do not account for the high Na content of many NaCW. The higher PCO2 required may be due to oxidation of organic matter of the sediments and, perhaps, to further addition of CO2 coming from deeper crustal levels, from the mantle, or from other sources. Na-Ca exchange involving a Na-exchanger could be an alternative genetic hypothesis. At present, however, at least for some areas (e.g., Northern Apennines, Italy), this hypothesis is not supported by mineralogical evidence.抄録全体を表示PDF形式でダウンロード (761K) -
Yoshihiro Ujiié, Yuuki Arata, Miyabi Sugawara2003 年 37 巻 3 号 p. 367-376
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーSpores and pollen are regarded as possible progenitors of petroleum. They are transformed into type II kerogen in sediments during diagenesis, which generates petroleum hydrocarbons on catagenesis and metagenesis. Living-pollen grains of Pinus thunbergii were heated to 290°C for 24 hours under the atmosphere in the laboratory to investigate the changes in physical and chemical properties of pollen with regards to the hydrocarbon generation. It was shown that heated pollen grains have decreasing trends in weight, size, atomic H/C ratio and stTAI, but an increasing trend in atomic N/C ratio with increasing temperature, especially in the higher temperature region. The changes in the atomic H/C ratio indicated that hydrocarbon generation from living-pollen grains should take place in the temperature range of about 135 and 230°C.抄録全体を表示PDF形式でダウンロード (2042K) -
Yi Yan, Ge Lin, Yue-Jun Wang, Feng Guo, Zi-An Li, Xiao-Ming Li, Chongb ...2003 年 37 巻 3 号 p. 377-389
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーThe apatite fission track (FT) analysis of Jurassic sandstones from the Beipiao basin in the eastern China indicates a large variation in FT age peaks. The sandstone of the Beipiao Formation has two peak ages at 178.8 and 40.0 Ma, while the sandstone of the Tuchengzi Formation has three age peaks at 152.0, 77.5 and 32.5 Ma. This implies that the provenance of the Beipiao basin in the early Jurassic and later Jurassic changed obviously. According to the Mesozoic regional thermo-tectonic evolution of the Yan-Liao orogenic belt, these apatites with different FT ages possibly represent different source components, although partial annealing had occurred to these apatites. The apatites of the oldest peak age (178.8–152.0 Ma) possibly originated from the pre-Mesozoic sedimentary covers of the North China Block (NCB), while the apatites of the intermediate peak age (77.5 Ma) and the younger peak age (40.0–32.5 Ma) came from the underlying Archean basement rocks and the Mesozoic volcanic detritus respectively. It is recognized that the basin sediments in the early Jurassic are composed of the Mesozoic volcanic detritus and pre-Mesozoic sedimentary detritus eroded from the uplifted regions around the basin. The existence of the intermediate peak age in the Tuchengzi Formation implies that the Archean basement rocks of the NCB might have become an important source of the upper Jurassic, which responded well to the south-southeast-trending thrust faulting in the northern of the NCB. Apatite FT ages of both the lower and upper Jurassic sediments in the Beipiao basin have a major peak age (30–40 Ma), which perhaps recorded an important Cenozoic thermo-tectonic event accompanied by the intensive rifting, basin subsidence and strong basaltic magmatism in the North China Block. Given a paleo-thermal gradient of 30°C/km, it can be deduced that the Liaoxi area has uplifted about 3 km at an average rate of about 0.1 mm/a since 30–40 Ma.抄録全体を表示PDF形式でダウンロード (232K) -
Xu Cheng, Huang Zhilong, Liu Congqiang, Qi Liang, Li Wenbo, Guan Tao2003 年 37 巻 3 号 p. 391-399
発行日: 2003/06/20
公開日: 2008/04/08
ジャーナル フリーConcentrations of PGE and Au of seven carbonatite samples from the Maoniuping REE deposit in China are reported (ppb): Ir 0.50∼0.78, Ru 1.61∼6.75, Rh 0.08∼0.14, Pt 2.62∼12.15, Pd 1.11∼3.65 and Au 1.24∼8.61, respectively. The primary mantle-normalized PGE distribution patterns reveal “swallow type” curve, with enrichment in Ru, Pt, Pd in comparison with Ir, Rh, and are similar to those of harzburgite in Dazhuka, Tibet, China. Nobles-metals reveal different trend with increase of Zr/Hf ratios. The preliminary study indicates that the overall PGE abundances of carbonatites are higher than the averages of MORB and OIB; the PGE of carbonatites underwent multi-source evolution. Fluids derived by metasomatism and subduction may transport PGE into carbonatite magmas. We suspect that besides the role of sulfides, volatile and alloys may modify PGE distribution patterns in carbonatite magma.抄録全体を表示PDF形式でダウンロード (209K) -
Yuji Orihashi, Takafumi Hirata2003 年 37 巻 3 号 p. 401-412
発行日: 2003/06/20
公開日: 2009/02/06
ジャーナル フリーWe have developed a rapid and precise analytical technique for the determinations of Y and rare earth elements (REE) from silicate rock samples by preparing XRF glass beads and using laser ablation (LA)-ICP-MS. Combined with XRF analysis, abundances of 39 major and trace elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti; Ba, Ce, Co, Cr, Dy, Er, Eu, Ga, Gd, Ho, La, Lu, Ni, Nb, Nd, Pb, Pr, Rb, Sc, Sm, Sr, Tb, Th, Tin, V, Y, Yb, Zn, Zr) for around 30 powder samples of silicate rocks can be measured successfully within five days. The method was applied to twelve GSJ rock reference materials (JA-1, JA-2, JA-3, JB-1a, JB-2, JB-3, JG-1a, JG-2, JG-3, JGb-1, JR-1 and JR-2) to assess the precision and accuracy of our data. The data obtained from the GSJ rock reference materials reveals that most of the data ranging from the mafic to intermediate rock materials show good agreement with the compiled values reported by Imai et al. (1995) within ±20%. Though, the heavy-REE (Gd-Lu) for the felsic rock materials (e.g., JG-1a, JG-2, JR-1 and JR-2) showed large discrepancies compared with the compiled values, other elements are in good agreement. This can be explained due to the erroneous measurement of compiled values which may be attributed to incomplete dissolution of the rock materials for solution techniques.抄録全体を表示PDF形式でダウンロード (562K)
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