Ferrugineous sinters from various origins and synthetic hydrous ferric oxide were investigated by DTA, TG, and X-ray diffraction techniques and chemical analysis. The samples studied showed an endothermic peak at 100° due to dehydration and an exothermic peak at 850°, possibly due to the formation of α-Fe₂O₃. From DTA curve, natural samples can be divided in the following three groups: (1) Those having an endothermic peak at 650°, which is characteristic to the sinters formed at pH's below 5.4. The peak represents the elimination of SO₃. (2) Those having an exothermic peak at 650°, but without any weight loss. The sinters, high in SiO₂ and/or Al₂O₃ and formed at pH's above 5.6, belong to this group. (3) Those having exothermic peaks at 650° and 750°. No weight change was recorded for these peaks. The sinters of this group are similar to those the second group in the chemical composition, but low in SiO₂. The effect of formation pH on thermal behavior of the sinters was also confirmed by synthetic studies.

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This paper presents the discussion on the balance of water and the transport of tritium, among three geohydrologic zones of Musashino groundwater basin. The discussion leads the estimation of the annual recharge to the groundwater from presipitation assuming the following data. 1) Time variation of tritium content in precipitation 2) Time variation of tritium content in the unconfind groundwater 3) Quantities of pumped out water from the confind groundwater 4) Tritium distribution of the whole basin In Musashino groundwater basin, this estimation gives the value of 0.50±0.16 m/y for the rate of precipitation recharge to the groundwater.

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The writers have studied the generation and migration of oil and gas in Japan from the geochemical viewpoint and the results are summarized as follows: In the Niigata gas fields, methane is recognized in the whole geothermal horizons; ethane is only found in those over 40℃ and propane is over 60℃. On the other hand, the results of geochemical surveys, such as CPI of normal paraffin wax, hydrocarbonization index and distribution of gaseous hydrocarbons for several deep stratigraphic wells drilled in the oil productive areas of Japan, suggest the principal oil generation has occurred during diagenetic to catagenetic stages. Therefore, both early and late oil generation hypotheses may be applied for the Neogene formations in Japan. From the analyses of perylene, Ni-porphyrin and VO-porphyrin in muddy core and crude oil samples of the Mitsuke oil field in Niigata prefecture, downward migration for the oil in upper reservoirs and lateral and upward for lower reservoirs are concluded. The weight ratios of hydrocarbons in reservoirs to source rocks in several Japanese oil fields ranges from 1/3 to 1/15. These values are much higher than those in the United States. As the weight ratios of estimated oil in reservoirs to expelled interstitial water are much more higher than the solubility of liquid hydrocarbons in water, oil had not been migrated from source rocks to reservoirs in the form of true solution.

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As a part of a study of diagenesis in the lake sediment, total organic carbon, carbohydrate, protein and amino acid, fat (lipid) and humic acid were determined in the core samples with 1.5 m and 200 m length from Lake Suwa and Lake Biwa respectively. It was found that fat shows the great decrease with depth followed by protein and amino acid and then carbohydrate in the surface to subsurface layers of the sediment whereas much slow vertical decrease in these organic materials occurs in further depths of the sediment. The decomposition reaction of the organic matter in the sediment was found to be first order. The decay rate constant was calculated to be n×10^-5 yr.^-1. Monosaccharide and fatty acid compositions of the sediment from Lake Suwa were deter- mined. It was found that marked change in the composition of these organic materials with depth occurs in the surface to 50 cm depth. To make clear the vertical change in organic materials and their composition, the surface sediment of Lake Suwa was allowed to incubate with or without sodium chloride and carbon dioxide, methane and ammonia produced were measured. The results obtained indicate that decarboxylation and deamination reactions play an important role for the decomposition of organic matter in the surface layer of the lake sediment.

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In order to designate the proper source rocks for the Japanese Tertiary oil, organo-geochemical study on the Japanese oil-producing sediments and crude oils has been carried out. The geochemical approach has included organic carbon analysis, identification of various hydrocarbons, determination of CPI value and metal porphyrin content, and kerogen analysis. It is suggested that most of the rocks belonging to the Onnagawa and the Funakawa Formations of middle Miocene age can be recognized to be the proper source rock for the Japanese Tertiary oil, on the basis of comparison of those rocks with the source rock criteria presented by some workers and the specific chemical relationships such as the Ni/V porphyrin ratio, concentration of polycyclic aromatics and CPI values between crude oils and their presumed source rocks. The data of the depth-porosity curve, the geothermal gradient and the vertical evolution of organic matter constituents obtained in the Kameda oil field, Akita Prefecture lead to the conclusion that the petroleum hydrocarbon was formed by thermal degredation of organic matter near the boundary of the Kameda and the Gongenyama Formations of middle Miocene age in the time of deposition of the Kitaura Formation of late Miocene age, and the burrial depth and the temperature required for petroleum genesis in that time were about 1200-1300 m and 60-70℃ respectively.

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Methane, crude oil and the associated water from oil and natural gas fields in Japan have been analyzed isotopically. In all of natural gas fields studied, gases occur with water in sand and gravel beds of Quaternary to Tertiary, consisting mainly of CH₄, CO₂, N₂ and Ar. δ¹³C values of methane are distributed in a rather narrow range from -64 to -75‰ relative to PDB. Those of CO₂ in gas phase are in ranges from +2.0 to -21.2‰ and carbonate materials dissolved in water from +9.3 to -7.1‰. For all of natural gas well studied, CH₄ is most depleted in ¹³C, whereas CO₂+HCO₃^-+CO₃⁼ in the associated water is most enriched in ¹³C. Carbon isotopic fractionation between CH₄ and CO₂ varies linearly with temperature of associated water. The isotopic temperatures calculated by using Bottinga's fractionation factor agree rather well with temperatures of associated water (13 to 59℃) measured at the ground surface. It can be concluded from these results that CH₄ and coexisting CO₂ produced by unidirectional reactions have reached an isotopic exchange equilibrium through enzyme reactions. This suggests bacterial processes of gas productions. Hydrogen isotopic compositions of associated waters of natural gases vary widely from + 1.9 to -82.2‰ relative to SMOW, depending on sedimentary environments of gas reservoirs- marine and fresh water. δD values of CH₄ range from -148 to -239‰, being smaller than those of associated waters. A linear relationship for δD values was found between CH₄ and the coexisting water throughout all natural gas fields. The linear relationship can be given as follows:
δD_CH4 = δD_H2O-(160±10) in permil
This means that the difference in the hydrogen isotopic composition between CH₄ and water is constantly 160‰ for a large extent of δD values. Since the difference in δD values between CH₄ and water in the isotopic exchange equilibrium should be theoretically less than 70‰, such a large fractionation is supposed to have resulted from a kinetic isotope effect in the process of methane formation in water. From the constancy of the difference in the isotopic composition and the kinetic isotope effect, it is possible to conclude that CH₄ and the associated water have a genetically close correlation and the associated water should be called "connate water". Oil samples studied have been collected from Tertiary formations in Japan. δ¹³C values are rather constant, ranging from -22.2 to -24.7%o for seven oil fields. The carbon isotopic composition does not systematically vary with geologic age.

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