Non-radiogenic argon is generally observed in terrestrial rocks and can be classified into two components : atmospheric and non-atmospheric argon. Atmospheric argon is trapped both in unretentive sites such as the surface of minerals, grain boundaries, interstitials, etc. and retentive sites such as crystal lattices. The amount of atmospheric argon trapped in minerals or rocks is not so small, and depends on mineral structures, grain sizes or degree of alteration. Hence, old volcanic or sedimentary rocks may contain atmospheric argon when the rocks were formed. Among the non-atmospheric argon, excess ⁴⁰Ar occurs in such geological environments where high partial pressure of ⁴⁰Ar exists or rapid cooling prevents the complete degassing of the pre-existed ⁴⁰Ar in the rock. Excess ⁴⁰Ar in deep-seated rocks might have been produced as dissolved argon. Further, in some deep-seated rocks, ³⁶Ar has been observed to correlate with excess ⁴⁰Ar. Such ³⁶Ar might be brought from the earth's deep interior and may be primordial.

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Trace element analyses of marine sediments from the Bay of Plenty indicate that submarine geothermal activity does not contribute significantly to the trace element geochemistry of sediments in this locality. The terrigenous sediments are similar in composition to North Island greywackes and are probably derived principally from the erosion of Mesozoic greywackes on the western flanks of the Huiarau Ranges rather than from the Quaternary acid volcanics of the Taupo region. There is no evidence for the diagenetic remobilisation of manganese or other trace elements in the sediments of this locality.

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Natural abundance of ¹⁵N in organic and inorganic nitrogenous substances in land was investigated. Available data on ¹⁵N abundance of biogenic nitrogen were summarized. Denitrification is divided into four types on the basis of the mode of isotope fractionation and environmental conditions. According to the simplified model on nitrogen isotope balance, the contribution of denitrification on land to the global denitrification is twice as much as that in the sea. The mode of ¹⁵N distribution in biogenic substances was discussed along the biogeochemical cycle of nitrogen with special reference to the fractionation of nitrogen isotopes occurring in denitrification and nitrogen fixation.

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¹³C/¹²C and ¹⁸O/¹⁶O ratios were determined for carbonate minerals and graphites in. marbles from the contact metamorphic aureole in the Kasuga area, Gifu Prefecture, central Japan. ¹³C/¹²C ratios were determined also for carbonaceous materials in pelitic rocks. ¹³C/¹²C ratios of graphites in marbles approach the carbon isotopic range of coexisting carbonates, although they are considered according to their occurrence to be of biogenic origin. In a typical traverse of the carbonate aureole, carbon isotopic fractionation between calcite and coexisting graphite becomes regularly smaller toward the igneous contact. This strongly suggests that calcite and coexisting graphite approached isotopic equilibrium during contact metamorphism. When we assume an isotopic equilibrium between calcite and graphite, we can estimate carbon isotopic temperatures, which reasonably agree with temperatures estimated from the solubility of magnesium in calcite coexisting with dolomite and from a heat flow model. Carbon isotopic temperatures for the maximum contact temperature are estimated to be from 600 to 650°C. The thermal gradient estimated from carbon isotopic ratios is gentle and agrees with that estimated from a heat flow model. Carbon isotopic temperature is considered to represent a temperature, which is closest to the maximum temperature during metamorphism. Dolomite and coexisting calcite are considered to be in disequilibrium as to oxygen isotopes, although equilibrium between calcite and graphite is attained. This is probably due to the difference in resistivity between calcite and dolomite to oxygen isotopic exchange with hydrothermal water.

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By using tholeiitic basalt as a starting material, partitioning of REE, Ba and Sr between crystal phase and liquid phase was investigated at 20kb. In this investigation, the crystal phase composed overwhelmingly of clinopyroxene was separated with heavy medium and dealt with as a whole. According to the results of three runs, the concentration ratios of REE between the crystal and liquid phases exhibit features strictly similar to those of a partition coefficient function deduced by mathematical analysis of the chondrite-normalized REE patterns of some bulk rock samples with basaltic chemical compositions.

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The sediment cores were collected from four sites of Lake Shinji, Japan. The unsupported ²¹⁰Pb (²¹⁰Pb_excess) in surface layer ranged from 12 to 19 dpm/g, while the radium-supported ²¹⁰Pb was 1.4∼1.9 dpm/g. The ²¹⁰Pb_excess profiles decrease logarithmically with depth. Thus, the ²¹⁰Pb dating method is applicable for these cores. Taking into account the compression effect of sediments, the accumulation rates of Lake Shinji sediments for surface layer have been estimated to be 0.3∼0.5 cm/yr. The sedimentation rates range from 0.071 to 0.13 g/cm²·y.

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Hornblendes from epidote-hornblendites in the contact aureole of the younger granite in the Oeyama ultramafic body are concluded to have been formed by recrystallization of clinopyroxenite on the supply of water from the intruding granite. The value of δD of source water is estimated to be -60∼-65 ‰, which is definitely lower than -29∼-37 ‰ of water in granitic magma of the Kitakami mountainous district.

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Kinetic dissolution experiments show that the rate of Al³⁺ dissolution from microcline is greater in sulfuric acid than in hydrochloric acid of the same pH value and temperature. Approximately linear relations were obtained by plotting the concentration of Al³⁺ against those of H⁺, Cl^- and HSO₄^- in 27 water samples collected in the Kusatsu hot-spring area; the highest value of the correlation coefficients was found for Al³⁺ - HSO₄^-, which suggests that Al³⁺ and HSO₄^- might have been derived from the same source. Since sulfuric acid is considered to be formed at or near the earth's surface, it is reasonable to suppose that Al³⁺ in the thermal solution was extracted from wall rocks of relatively shallow depths under the influence of sulfuric acid.

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