巻号一覧
33 巻 (1999)
- 6 号 p. 355-
- 5 号 p. 285-
- 4 号 p. 215-
- 3 号 p. 141-
- 2 号 p. 73-
- 1 号 p. 1-
33 巻, 3 号
選択された号の論文の5件中1～5を表示しています
- |<
- <
- 1
- >
- >|
-
M. Guerra, G. Etiope1999 年 33 巻 3 号 p. 141-151
発行日: 1999/06/20
公開日: 2008/04/08
ジャーナル フリーGas samples for analysis of CO2, Rn and He were collected simultaneously in different types of natural occurrence, i.e., soil-air, groundwater, gas vent and soil-atmosphere exhalation flux, in the Siena-Rapolano geothermal area (central Italy). The results showed differential enrichment and depletion of Rn and He within small areas as an effect of gas-water partitioning and gas channelling in CO2-rich faulted subsoil. In the same site low concentrations of Rn or He in water co-exist with high concentrations in the ground; low Rn in soil-air occurs in correspondence with Rn-rich gas vents; soil-gas Rn may be higher than the level induced by U decay in the ground or outcropping rocks. These results suggest that the analysis of a single “sub-system” of the geological environment (e.g., groundwater analysis only) may not provide data representative of gas occurrence and abundance at the investigated site. This must be taken into account in natural resource exploration, earthquake precursor studies and radiation protection zoning based on gas geochemistry.抄録全体を表示PDF形式でダウンロード (2907K) -
Jong Ik Lee, Yong-Joo Jwa, Chung-Hwa Park, Mi Jung Lee, Jacques Moutte ...1999 年 33 巻 3 号 p. 153-165
発行日: 1999/06/20
公開日: 2008/04/08
ジャーナル フリーRb-Sr whole-rock isochron ages and Sr and Nd isotopic ratios have been determined for Youngju and Andong granites in the northeastern Yeongnam Massif, Korea. Six samples of Youngju granites yield an isochron age of 267 ± 27 Ma with an initial Sr ratio of 0.71505 ± 0.00026. Seven samples of Andong granites give an isochron age of 361 ± 41 Ma and an initial Sr ratio of 0.70944 ± 0.00011. The isochron ages indicate that Youngju and Andong granites were emplaced in middle Permian and late Devonian of late Paleozoic, respectively. Calculated εSr (T) and εNd (T) values at 267 Ma for Youngju granites are 152.2∼156.4 and -19.7∼-18.0, and those values at 361 Ma for Andong granites are 73.8∼79.7 and -11.4∼-8.0. Model ages of Youngju and Andong granites are 2.4∼3.3 Ga and 1.4∼1.8 Ga, respectively, suggesting that the Youngju granitic magma was derived from highly LREE-enriched lower crust formed in Late Archean, whereas the Andong granitic magma from slightly LREE-enriched lower crust formed in Proterozoic. Initial 87Sr/86Sr ratios of the granites in Ogcheon Belt and Yeongnam Massif display a broad range, but have two peaks around 0.709 and 0.715 regardless of emplacement age. It is likely that these two kinds of sources which are isotopically different have widely existed in the lower crust of Ogcheon Belt and Yeongnam Massif.抄録全体を表示PDF形式でダウンロード (3416K) -
Iwao Kawabe, Atsuyuki Ohta, Satoru Ishii, Maki Tokumura, Kazue Miyauch ...1999 年 33 巻 3 号 p. 167-179
発行日: 1999/06/20
公開日: 2008/04/08
ジャーナル フリーDistribution coefficients of Kd (REE: ppt./sol.) with REE = lanthanides (Ln), Y, and Sc between Fe-Mn oxyhydroxide precipitates and NaCl solutions have been determined in pH = 5.4-6.4 at room temperature and atmospheric pressure. The logKd(Ln) values show convex tetrad effect variations across the series and positive Ce anomalies. Kd(Y) values are significantly lower than those for Ho and Er, whereas Kd(Sc) values are higher than those for Lu. Behaviors of Y3+ and Sc3+ are distinct from heavy Ln3+ when REE coprecipitate with Fe-Mn oxyhydroxides in weakly acid solutions. The observed convex tetrad effect variations of logKd(Ln) are commonly modified from theoretically expected ones in light Ln and heavier Ln. The variations of logKd(Ln) across the series are related to {ΔGof(Ln3+, aq)-ΔGof(Ln(OH)3.nH2O) } for the following reactions between Ln3+(aq) and Ln(OH)3.nH2O as precipitate: Ln(OH)3.nH2O(ss) + 3H+(aq) = Ln3+(aq) + (3 + n)H2O(l). Hence, the variations of logKd(Ln) reflect (i) the tetrad effect originating from differences in Racah E1 and E3 parameters for 4f electron repulsion in Ln3+ ions between the two Ln(III) series, and (ii) the changes of coordination states of Ln3+ ions in the respective Ln(III) complex series. The structural changes of the first-coordination spheres of Ln3+ ions in light Ln3+(aq) and heavy Ln(OH)3.nH2O series make the series variation of logKd(Ln) irregular. When we correct the logKd(Ln) values for the structural changes, they become regular tetrad effect variations compatible with the refined spin-pairing energy theory. Racah parameters for 4f electron repulsion in Ln3+ ions of octahydrate Ln3+(aq) series are inferred to be larger than those of Ln(OH)3.nH2O.抄録全体を表示PDF形式でダウンロード (3554K) -
Iwao Kawabe, Atsuyuki Ohta, Noriko Miura1999 年 33 巻 3 号 p. 181-197
発行日: 1999/06/20
公開日: 2008/04/08
ジャーナル フリーDistribution coefficients of REE between Fe oxyhydroxide precipitates and NaCl solutions doped with NaHCO3 have been determined in pH = 8.1-8.6 and at room temperature and pressure. The coefficient is defined as Kd(REE: ppt./sol.), where REE designates each lanthanide (Ln), Y or Sc. The NaHCO3 concentration was changed in the range of (0∼12) × 10-3 M under a constant NaCl concentration (0.45 M). Kd(Sc) rapidly approaches Kd(Lu) as [NaHCO3] increases. Kd(Y) is lower than Kd(Ho) even in solutions with high [NaHCO3]. The convex tetrad effect in logKd(Ln) becomes less conspicuous with increasing [NaHCO3]. We proposed a method to determine REE-carbonate complexation constants from observed variations of Kd(REE) with increasing [CO32-, aq]. In solutions with [NaHCO3] ≥ 1 × 10-2 M, the dominant dissolved REE species are REE(CO3)2-(aq) except for La. We have tentatively determined the stability constants of β2 for REE(CO3)2-(aq) from our preliminary data set, although β1 for REECO3+(aq) could not be estimated. The series variation of logβ2 are compatible with literature values. On the basis of the refined spin-pairing energy theory (RSPET), we have analyzed the series variations of logβ2 and logKd(Ln) values with and without Ln(III)-carbonate complexation effect. Racah E1 parameter is approximately the same between Ln(OH)3·nH2O as the precipitate and Ln(CO3)2-(aq), whereas Racah E3 parameter of Ln(CO3)2-(aq) is only slightly larger than that of Ln(OH)3·nH2O. This is the reason that the convex tetrad effect of logKd(Ln) diminishes as Ln(III)-carbonate complexation proceeds. Our experimental logKd(Ln) values and apparent logKd(Ln) ones from marine Mn-Fe deposit/seawater pairs suggest that reported log(β1/β2) values for light Ln are slightly smaller than those ought to be.抄録全体を表示PDF形式でダウンロード (4763K) -
Xiong Xiao-Lin, Zhao Zhen-Hua, Zhu Jin-Chu, Rao Bing1999 年 33 巻 3 号 p. 199-214
発行日: 1999/06/20
公開日: 2008/04/08
ジャーナル フリーPhase relations were experimentally determined in albite granite-H2O-HF system with 2, 4 and 6 wt.% fluorine at 100 MPa pressure. With the increase of fluorine content from 2 to 6 wt.% in the system, liquidus temperature increased from 768 to 790°C and the solidus temperature decreased from 540 to 490°C. Maximum temperature of quartz and topaz stability field increased with F content, whereas that of alkali-feldspar decreased and its stability field disappeared at 6 wt.% fluorine. The mineral assemblage of topaz granite (quartz + albite + K-feldspar + mica + topaz) was stable above solidus at F ≤ 4 wt.%, and that of topaz greisen (quartz + topaz + mica) was stable above solidus at F = 6 wt.%. The experiments showed that the residual melt with high F content can be formed by fractional crystallization of a leucogranitic melt with relatively low F content. These experimental results provide reliable evidences for the formation of topaz granite and topaz greisen at low temperature magmatic conditions.抄録全体を表示PDF形式でダウンロード (4628K)
- |<
- <
- 1
- >
- >|