A vacuum ball mill was devised to extract volatiles from fluid inclusions in minerals. A special feature of the crushing mode is the horizontal oscillation of the mill, which enhances crushing efficiency and overcomes the fragility of the mill, which is made of Pyrex glass. This ball mill is equipped with a cold finger trap cooled with liquid nitrogen to reduce the influence of adsorption of once extracted volatiles on to mineral powder during the crushing process. Amounts and isotope ratios were determined for water extracted from the fluid inclusins of quartz and halite. The determinations were made for CO2 as well in fluid inclusions of quartz. The influence of adsorption on amounts and isotopic ratios of volatiles was evaluated by comparing the results of repeated extractions with and without the liquid nitrogen trap during the crushing process. In a single run of extraction, two kinds of water were obtained: one was water trapped in the cold finger trap during the crushing, the other was desorbed water given by heating of the sample after crushing. A simple summation of the isotope ratios of the desorbd and the trapped waters gives an erratic result in comparison with the original isotope ratio. As for the fluid inclusions in hydrothermal quartz, the original δ18O and δD values for water in the inclusions can be estimated by applying Rayleigh's equation to the adsorption process. In the case of halite samples, however, the estimation of the original δ18O and δD values is much more difficult because of the formation of hydrate salts. However, in the special case where the brine in inclusions is a pure NaCl solution, the original inclusion water is simply the sum of the desorbed and trapped waters. For CO2 analysis of inclusion fluids, the adsorption during the crushing process is negligibly small, not affecting appreciably the results on δ13C and δ18O values.
Fluid inclusions in olivine were extracted in vacuum by a sodium carbonate fusion method. In the present study, bulk hydrogen content and D/H ratio of the inclusion were measured. The results showed that a consistent value of δD was obtained with a standard deviation of ±2‰, when the absolute amount of hydrogen extracted was more than 40μmol (0.9ml STP H2). On the other hand, when the absolute amount of extracted hydrogen was less than 40μmol, δD value of the extract fluctuated, probably being affected by the contamination in the whole procedure.
The vapor pressures of solid D 2 O and ice containing D 2 O in various amounts were measured with an oil manometer. The result gives the lowest vapor pressure for D 2 O ice ever obtained. The observed value for ice with different proportions of D 2 O and H 2 O agreed well with the values calculated on the assumption that the vapor pressure of HDO is the geometrical mean of those of H 2 O and D 2 O and that the equilibrium constant of isotopic exchange is 4. The fractionation factor of D between ice and vapor phases increases from 1.128 at 0°C to 1.210 at —38°C.
Monthly variation of δD and δ18O of two fumarolic condensates, five hot spring waters, two stream waters, and meteoric precipitation at the Nasudake volcanic area of Japan was measured. There was no remarkable variation with time in the isotopic ratios of the samples except for meteoric precipitation and for one of the hot spring waters. The δD and δ18O of meteoric precipitation showed seasonal change with summer maximum and winter minimum. The δD and δ18O of the stream waters and two of the hot spring waters were identical with those of average precipitation. On the basis of this fact and by using a simple mixing reservoir model, the residence time of precipitation water under the ground was calculated to be not shorter than a few years. Precipitation did not directly affect the isotopic ratios of volcanic waters. A general feature of the δD versus δ18O diagram for the above samples was similar to that for the samples obtained from worldwide geothermal systems, namely, thermal waters exhibited oxygen isotopic shift. Deuterium content of thermal waters was found to be higher than that of surface waters by 7‰ on the average. This slight enrichment of deuterium was inferred to be due to subsurface clay formation.
Quartz, K-feldspar, albite and anorthite were equilibrated with water vapor in Pt capsules at 20kb and in the temperature range from 800 to 1, 300°C. The water in the capsules during the high temperature and pressure run seems to exist in two states, aqueous fluid and dissolved water (structural water) in the melt. In the process of extracting these waters, four kinds of water were distinguished experimentally: 1) Water extracted by puncturing the capsule in vacuum, 2) Water released from bubbles in quenched products, i.e., glasses, during grinding in an agate mortar, 3) Water extracted from pulverized product in evacuation process at room temperature, and 4) Water extracted in vacuum at high temperature. D/H ratios of waters of 1), 3) and 4) were measured. Taking water 4) to be dissolved water in melt, the fractionation factors between this and other waters from aqueous fluid were estimated. Deuterium is enriched in the dissolved water for albite and K-feldspar melts, D/H is almost the same for the aqueous fluid and dissolved water in the anorthite melt, and deuterium is much depleted in the dissolved water in the quartz melt.
Method of chemical separation for nitrogen compounds in soils established by BREMNER (1965) was checked and modified to apply for the measurement of the natural variation in isotopic ratios of nitrogen compounds in sediments. Separation of nitrogen compounds which exist in different occurrences i.e., (a) in interstitial water, (b) in the exchangeable site on the surface of solid, and (c) in solid, was also studied, and the optimum conditions for the separation were determined.
