More than 140 thermal waters of Japan were studied isotopically and chemically. Highly saline brines at Arima and Takarazuka, Hyogo-Ken, and Ishibotoke near Osaka indicate wide ranges of δ¹⁸O and δD values from meteoric values of δ¹⁸O = -8.2 and δD = -50.0 ‰ SMOW to highly shifted values of +6.5 and -27.8 ‰, respectively. The isotopic values of these brines vary proportionally with chloride concentration irrespective of temperature, carbonate concentration or locality. These saline waters are isotopically and chemically best explained as the mixtures of local meteoric waters and a saline brine of Cl^-= 43, 700 ppm, δ¹⁸O = +8 ‰ and δD = -30 to -25 ‰. The latter is most likely the “residual magmatic, metamorphic or geothermal” fluid associated with upper Cretaceous rhyolitic and granitic rocks and Ryoke metamorphic rocks in which these brines are found. Thermal waters at Ikeda and in adjacent areas, Shimane-Ken and at Senami, Niigata-Ken, are similar to the Arima brines in the isotopic and major element chemistry, but are much more diluted by the respective local meteoric waters. Many of the thermal waters along the ocean coasts are isotopically intermediate between oceanic and local meteoric waters and are considered to be mixtures of the two types of water. As a result of hydrothermal mineral-sea water interaction, the coastal thermal waters differ considerably in the chemistry from fresh sea water and are typical of Na-Ca-Cl type. The coastal thermal waters isotopically and chemically may be similar, if not the same, to submarine hydrothermal ore fluids responsible for the Kuroko type mineralization. The isotopic values and their relationship to salinity, however, widely differ from one system to another depending on the hydrogeological conditions of each system. The coastal thermal waters at Ibusuki of Ata Caldera, Kagoshima-Ken, for instance, are significantly affected by the waters from three crater lakes, Lake Ikeda, Unagi-Ike and Kagami-Ike, in which the δ¹⁸O and δD values are meteorologically balanced at such high values as -2.6 and -19.4‰, respectively. Acid to neutral thermal waters of volcanic affiliation indicate varying degrees of isotopic shifts, but they are supposed from their δD values to be essentially derived from recycled meteoric water. Many thermal waters of neutral chloride type in the “green tuff” regions of the inner Honshu also are simple meteoric in origin without showing any significant isotopic shifts, although the waters are relatively high in salinity and SO₄/Cl ratios.

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The δ¹⁸O and δD values of water of crystallization of gypsum from the Kuroko type mineralization in Japan mostly fall in narrow ranges from -6 to -8 and from -75 to -90‰, respectively. While the mineralization has generally been accepted as of submarine hydrothermal origin, the present results indicate that the gypsum ores are in isotopic equilibrium with meteoric waters instead of sea water. The most plausible interpretation for this observation is that the primary submarine anhydrite or gypsum was hydrated or re-equilibrated with meteoric waters after the uplifting of the deposits. However, there is some evidence that meteoric hydrothermal solution might have been involved in certain stages of Kuroko mineralization at Shakanai. The δ¹⁸O and δD values of gypsum of the Tsutsumizawa deposit in Hanaoka, Northeast Honshu, fall on a line with a slope (δD/δ¹⁸O) of -5.3. This suggests that the deposit was formed by fractional hydration of an anhydrite deposit under a limited supply of water, of which isotopic ratios were similar to present-day meteoric waters. Gypsum ores of Noto and Osaka-Matsushiro, Southwest Honshu, are isotopically quite different from most of other Kuroko deposits. These gypsum ores seem to have been hydrated by hydrothermal waters which isotopically are significantly shifted from meteoric waters.

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Coprecipitation of organic matter with ferric and ferrous hydroxide, and iron holding in solution containing organic matter were experimentally studied. The dissolved organic matter from bacterial degradation of green algae was used. The results of the experiments showed that ferrous iron, as well as ferric iron, coprecipitate organic matter under reduced conditions, and that ferric and ferrous irons selectively coprecipitate proteinous materials. On the contrary, pigment and lipid materials are rarely coprecipitated, and hold ferric iron in dissolved form probably by forming water soluble iron-organic complexes. These results show the significance of the interaction of organic matter and iron in the cycle of them in the hydrosphere.

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A new quantity, non-anorthitic silica (nasa), is defined in this paper. Empirically, there is a logarithmically linear relationship between RE and nasa for Apollo 16 samples including typical anorthosites. Extension of this line appears to pass through KREEP. Mare basalts form a different series in this diagram. Based on RE patterns, in particular, Ce anomaly and on the oldest age of Apollo 16 anorthositic complexes, it is suggested that we had better reserve the speculation that anorthosites originated mostly from the anorthositic planetesimals which formed from the gases derived from the earth's silicate surface. Furthermore, it might be imagined that the earth's surface material had been more or less fractionated at the time of evaporation. The RE data on 60015 and 15016 are presented. For 60015, both main inner part (anorthosite) and dark coating were investigated.

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