巻号一覧
23 巻 (1989)
- 6 号 p. 269-
- 5 号 p. 215-
- 4 号 p. 149-
- 3 号 p. 91-
- 2 号 p. 45-
- 1 号 p. 1-
23 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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Takanori Nakano1989 年 23 巻 3 号 p. 91-99
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーA model incorporating experimentally determined fluid-crystal cation exchange equilibrium constants is proposed to explain compositional variations in clinopyroxene from Japanese skarns. The proposed “Fluctuation Model” can account for the observed compositional heterogeneity in both individual and aggregate clinopyroxene grains on a thin section scale. The model assumes formation from a hydrothermal solution whose mean concentrations of magnesium, manganese and iron components remained essentially constant throughout crystal growth period at constant temperature and pressure. Compositional heterogeneity developed as a result of local spatial and temporal fluctuations about the mean solution component concentrations. The degree of fluctuation in the proportion of component i in the hydrothermal solution, as defined by the percent coefficient of variation, CVi, is linearly related to the mean mole percent, Mi, of the component in the hydrothermal solution by the equation CVi=0.25×(100-Mi). Various compositional patterns off naturally occurring skarn clinopyroxenes can be closely reproduced by the model.抄録全体を表示PDF形式でダウンロード (2268K) -
Francesca Castorina, Riccardo Petrini1989 年 23 巻 3 号 p. 101-109
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーAn iterative procedure, based on the implemented Gauss method, has been applied to the radioactive decay law as used in geochronology, in order to refine the age and initial isotopic composition parameters. The method furnishes some statistical information about the fitting, obtained during the iterative path, such as the correlation coefficient between parameters and the residual/standard deviation ratio for each of the regressed points. In particular, the ratio between residuals and standard deviation is a tool to evaluate how each point influences the linear regression in relation to its actual scatter from the best-fit line. It is believed that this approach may be useful if coupled with standard isochron calculations. As an example, the method has been applied to date some Hercynic leucogranites outcropping in the Buddusò intrusive complex (NE Sardinia, Italy). The iterative least-squares procedure allows to remove from the fitting some samples which were perturbed with respect to the Rb-Sr systematic. The isochron calculated on the selected rocks yields an age of 274±9 Ma, which dates the last isotopic homogeneization event, and could represent the emplacement age of the leucogranites. Furthermore, biotite minerals separated from the leucogranites yield an isochron age of 272±7 Ma, thus indicating a possible high cooling rate of the granitic intrusion.抄録全体を表示PDF形式でダウンロード (2326K) -
Masahito Sugiyama1989 年 23 巻 3 号 p. 111-116
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーMonthly survey of dissolved vanadium concentration in Lake Biwa has clearly revealed a seasonal variation hitherto unreported. In the surface layer of the lake, dissolved vanadium concentration started to increase in May, reached a maximum value in late summer, and decreased in fall. By contrast, in the bottom layer (70 m depth), the concentration remained almost constant throughout the year. The increase of dissolved vanadium concentration in the eutrophicated southern basin of the lake was greater than the one in the mesotrophic northern basin.抄録全体を表示PDF形式でダウンロード (1494K) -
Yoshiro Tsuzuki1989 年 23 巻 3 号 p. 117-128
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーHydrothermal alteration is characterized by a change in the mineral composition (mode) of rocks in water-rock systems. The mode of rocks is changed by reaction between minerals and solution, with the composition of the solution also changing as a result of the reaction. The composition of the splution within a hydrothermal system under set conditions is given by simultaneous equations which are based on formulae of each mineral, and written in a matrix form. On the basis of mass balance between the minerals and the solution, the amounts of minerals dissolved and precipitated due to changing conditions are given by simultaneous equations which are also written in a matrix form. The latter matrix is transposed from that of the former. The change in the mode due to changes in the physicochemical condition is obtained by combining the two calculations given above. The calculations are applied to hydrothermal alteration in a system in which there is a geothermal gradient and circulation of hydrothermal fluid. For a system involving a solution and rock consisting of quartz, feldspars, muscovite and others, a decreasing temperature results in an increase of quartz and muscovite and a decrease in the amount of feldspars. In systems where the number of mineral phases is more than that of metal elements, stable mineral assemblages in the solution are examined in a model in which the solution interchanges among domains in a rock. One example is the Al-Si system involving solution, quartz, gibbsite and kaolinite. The results indicate that the stable mineral assemblages under set conditions depend on the original mode. Formation of veins accompanied by wall rock alteration is calculated in the system described above. The result indicates the formation of quartz veins with temperature decrease; the general feature of wall rock alteration can also be predicted.抄録全体を表示PDF形式でダウンロード (3152K) -
Vimonrut Kasemsupaya, Mayumi Yashima, Hiroyuki Tsubota, Yoshiyuki Noza ...1989 年 23 巻 3 号 p. 129-138
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーMeasurements of 228Ra, 226Ra and 210Pb in the waters of Tokyo Bay and Osaka Bay mixing zones are presented. 228Ra concentrations and the activity ratios of 228Ra/226Ra are considerably higher in Osaka Bay than in Tokyo Bay. This probably reflects the different riverine/estuarine input of 228Ra from the two geologically different drainage zones of Tokyo Bay and Osaka Bay areas (volcanic versus granitic), because of the way in which 228Ra, a daughter of 232Th, is leached and transported by rivers. The Ra isotope distributions follow the trend of conservative mixing with open ocean water in which Ra isotope concentrations are low. Using a simple box-model, we estimate a value of 1.4±0.2 months for the mean residence time of Osaka Bay water and a value of 0.25 dpm cm-2y-1 for the 228Ra flux from Tokyo Bay sediments. In contrast to 228Ra, 210Pb concentrations in Tokyo Bay and Osaka Bay waters are the same and nearly constant at 34 dpm/103l, a value considerably lower than 200 dpm/103l in the Kuroshio surface water. The non-conservative behavior of 210Pb during mixing demonstrates that 210Pb is rapidly removed near the front of Kuroshio Current far outside the bays, and hence there is no significant lateral input of 210Pb from offshore to the two bays. The mean residence time of 210Pb in seawater is also calculated to be 2 weeks for Tokyo Bay and 3 weeks for Osaka Bay.抄録全体を表示PDF形式でダウンロード (2615K) -
Shun-ichiro Igari, Susumu Sakata1989 年 23 巻 3 号 p. 139-142
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーCarbon isotopic ratios of methane (δ13C(C1)) and chemical compositions were measured for natural gases of dissolved-in-water type (dissolved gases) from several gas fields in Japan. Most of the samples have low δ13C(C1) values (-69.1∼-66.4‰) and contain small amounts of C2+(CnH2n+2, n≥2) hydrocarbons. These two features indicate that they are of biogenic origin as has been suggested by previous researchers. However, several samples from the Yaizu gas field have high δ13C(C1) values (-34.3∼-33.8‰) which cannot be of biogenic origin, but thermogenic origin. This is the first report to confirm the occurrence of dissolved gas of thermogenic origin in Japan.抄録全体を表示PDF形式でダウンロード (1035K) -
Atsushi Ando, Hikari Kamioka, Shigeru Terashima, Shiro Itoh1989 年 23 巻 3 号 p. 143-148
発行日: 1989年
公開日: 2008/04/08
ジャーナル フリーThe elemental composition data for seventeen GSJ rock reference samples, “Igneous rock series”, are compiled and presented as the 1988 concensus values for major, minor and trace elements. This compilation is based on previously published 1986 values and new 160 analytical reports we received during the years of 1987 and 1988. In the 1988 values, the 1986 values of poor reliability have been widely revised and many of data lacking in the former compilation are newly added.抄録全体を表示PDF形式でダウンロード (1222K) -
1989 年 23 巻 3 号 p. e1
発行日: 1989年
公開日: 2009/02/06
ジャーナル フリーPDF形式でダウンロード (452K)
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