Quantitative micro-analysis of silicate glasses has been developed using secondary ion mass spectrometry (SIMS). The standard rock references, issued by the Geological Survey of Japan (GSJ), were fused into glass beads and used as standards for SIMS analysis. Thirty eight elements at major, minor and trace concentration levels, were analyzed simultaneously on the standard glasses using an energy-filtering technique. In the concentration range of the glass standards, linear relationships were established for the following elements: Li, Be, B, Na, Mg, Al, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Rb, Sr, Y, Zr, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Hf. The typical accuracy of the analyses are within 10% of recommended values of GSJ standards for the elements over 1 ppm.

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The Upper to Middle Miocene mudstones from the MITI-Hamayuchi borehole in the northern part of Hokkaido, Japan, were analyzed for steroid and hopanoid hydrocarbons in the extractable organic matter. Maturity indicators based upon their distributions increase with increasing burial depth. The correlation between sterane 20S/(R+S) ratio and R_o (vitrinite reflectance value) is similar to that reported from the Niigata and Shinjo basins, whereas the correlation between steroid TA/(MA+TA) ratio and R_o shows a different trend from that from the Niigata basin. These diverse relationships may be attributed to differences in thermal histories of the samples and kinetic properties of the indicators. The paleogeothermal gradient of this borehole estimated by the extent of epimerization of C₂₉ steranes and C₃₂ hopanes is consistent with that estimated by the observation of authigenic zeolites (Sasaki et al., 1982).

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Some leucogranites from China have been found to display the tetrad effect (Masuda et al., 1987). Abundances of all rare earth elements (REE) in leucogranites from Hunan Province, China, were studied for the first time by inductively coupled plasma mass spectrometry (ICP-MS) in order to investigate the shape of the tetrad effect. The chondrite normalized REE pattern consisting of all members except Eu revealed a clear M-type tetrad effect, according to the classification by Masuda et al. (1987). Eu shows a strong negative anomaly. These features may reflect a long history of contact with water. Mathematical analyses of the REE patterns suggest also an octad effect behind the patterns and symmetry between the first (La-Ce-Pr-Nd) and fourth tetrads (Er-Tm-Yb-Lu).

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Low water/rock ratios (about 1 in weight) in discharge zone appear to be an important characteristic of submarine hydrothermal systems associated with axial spreading centers. These ratios, which are stable over time, are linked with the chemistry of end-member hydrothermal solutions (original hydrothermal solution before mixing with ambient seawater) and the chemistry and distribution of greenstones. These features are considered to result from the properties of an open flow system. This paper is an attempt to analyze a submarine hydrothermal system, using an ideal open flow model. In this model, seawater is percolating through a rock column which is divided into a number of cells. In each cell, both rocks and solutions come to equilibrium, based on strontium isotope exchange. The fundamental features of water/rock interaction in this flow system differ from those inferred from closed system; (1) chemical composition of the discharged solution can be kept constant for some while although large volume of recharged solution brings large change in the bulk chemical composition of the system. (2) The difference between chemical composition of recharged and discharged solutions is compensated by the large change of rock composition near recharge zone at earlier stage of hydrothermal system. (3) The values of water/rock ratio deduced from rock or solution chemistry are, in general, different from the integrated volume water/rock ratio. These results are applied to the natural subseafloor hydrothermal system. The features are classified in relation to three evolutionary stages: (1) Early stage: chlorite-quartz-(CQ-) and CQ-rich greenstones occur only in recharge zone while CQ-poor greenstones occur in the rest of the system. (2) Intermediate stage: the increase of fluid flow promotes replacement of CQ-poor with CQ-rich and some of CQ-rich with CQ-greenstones, respectively. (3) Late stage: CQ-poor greenstones are completely replaced by CQ- and CQ-rich greenstones. The integrated volume water/rock ratio ([W/R]_FLOW) constrained by the energy of heat source is estimated to be up to 4. So it is suggested that hydrothermal activity dies out by the intermediate stage. The chemical composition of end-member hydrothermal solutions stays constant through the early and intermediate stage. An increase of integrated water volume circulating through the system does not necessarily lead to change the chemistry of hydrothermal solution and host rock through the system.

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