Core samples from 14 boreholes were investigated to determine the smectite % and composition of exchangeable cations of mica/smectite in alteration area around the Yokota Kuroko deposit, which consists of upper and lower orebodies. The upper orebodies occur in the horizon between the Oshio and Takisawagawa Formations, and the lower orebodies in the strata 150 to 200m lower than the former.
Near the upper orebodies, the smectite % of mica/smectite decreases with depth from about 70% to 20% within 10m below the boundary between the Takisawagawa and Oshio Formations. On the otherhand, at a distance away from orebodies, smectite is converted to mica/smectite containing 40% to 30% smectite at 30 meters or more lower than Oshio-Takisawagawa boundary and mica/smectite zone increases in thickness. Stratiform ore bodies and veinlets are restricted within the zone of 10% smectite in the isopleth map at the bottom of the rhyolite of the Takisawagawa Formation.
Major exchangable interlayer cation in clay fractions in the Takisawagawa to the lowermost part of the Oshio Formations are generally Na+, while those in the lower to middle parts of the Oshio Formation are Ca²⁺.
The changes in smectite % and composition of exchangeable interlayer cation near the boundary between the Takisawagawa and Oshio Formations indicate that a decrease in hydrothermal activity and change in chemical composition occurred at the final stage of Kuroko mineralization.

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Petrography and bulk rock chemistry of volcanic rocks and plutonic xenoliths from HigashiIzu monogenetic volcano group (HIMVG), the Izu Peninsula, central Japan, revealed a bimodal volcanic activity-high alumina basalts to calc-alkaline andesites (SiO₂=48-59 wt%) vs. calcalkaline dacites (SiO₂=68-73 wt%)-. The samples include 7 rock types based on bulk compositions and phenocrysts assemblages; ol + pl ± aug basalts, ol + pl ± aug andesites, ol + pl ± aug + hyp andesites and pl + ho + hyp ± (ol + aug) dacites.
Two types of basalts and andesites with different modal compositions of xenocrystic minerals (corroded quartz and sodic resorbed plagioclase) are found in HIMVG, i.e. X-poor type (less than 1 vol% xenocrysts) and X-rich type (more than 1 vol% xenocrysts). The X-poor type includes mostly of basalts and shows iron enrichment on the SiO₂ vs. FeO^*/MgO diagram. On the other hands, the X-rich type with more than 1 vol% xenocrysts includes mostly andesites and does not show iron enrichment. In the X-poor type, modal composition of phenocrysts of olivine and chromian spinel, and bulk MgO, Ni, and Cr contents decrease abruptly with an increasing SiO₂, whereas in the X-rich type, contents of these elements are variable and decrease moderately.
Partialy fused granitic xenoliths from Omuroyama scoria cone contain quartz, partialy resorbed plagioclase, and glass. Bulk rock composition of these xenoliths are similar to that of dacites.
In the HIMVG area, a concentric zonal pattern of rock types and phenocryst assemblages are observed. The basalts erupted at outer zone, while andesites and dacites, at inner zone. The volcanic products had been basaltic and andesitic untill the eruption of Kawagodaira, after which they became andesitic and dacitic.

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A new method of evaluating the pareodose, the auther presented in 1988, extended the limits of the TL dating method to about 10⁶ years.
In the former article, consideration about the electron-trapping process produced the combination of a competition model and an ordinary saturation model. The competition model accounts for the supralinearity in the low dose range, and the ordinary saturation model explains the sublinearity in the high dose range. In the new method, the experimental data decide the coefficients of the equation directly, without the regressive error. Therefore, in many types of samples, the new method brought good results for evaluation of the pareodose.
In some cases, however, a few errors have appeared in the low dose range. In the former article, the electron-trapping probability of the competition model was doubly approximated, in order to make a solution easy. The double approximation caused a few errors in the calculation of TL responce, in the low dose range, Consequently, the former equation led a smaller value as a pareodose.
For the purpose of a solution, the approximate term of (1-e7^-CR) was exchanged for the correct term of (1+e^-CR+D)-1. The improved equation has offered better-fitting results with experiments, especially in the low dose range.
By this improvement, the new method has enhanced the reliability and has come to be of wide application.

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This paper summarizes macrostructures of individual ore bodies, mineral assemblages, mineralization stages, and oxygen isotopic data for quartz from veins and wall rock for copper-lead-zinc mineralization at the Hayakawa and Shakako deposits.
Chalcopyrite-pyrite-tetrahedrite-galena-sphalerite-bearing quartz veins (Cu-Pb-Zn quartz veins) and galena-sphalerite-bearing quartz veins (Pb-Zn quartz veins) occur at the Hayakawa and Shakako deposits. The Cu-Pb-Zn quartz veins formed earlier than the Pb-Zn quartz veins. The minerals in the Cu-Pb-Zn quartz veins include chalcopyrite, pyrite, tetrahedrite-tennantite, galena, sphalerite, enargite, bournonite, semseyite, hessite, kesterite, arsenosulvanite, Cu-Fe-Zn-Sn-S mineral, tetradymite, aikinite, quartz and apatite. The minerals in the Pb-Zn quartz veins are galena, sphalerite, pyrite, chalcopyrite, tetrahedrite, electrum and quartz. FeS content of sphalerite decreases from the earlier to later stages of mineralization. Distinct compositional heterogeneity between Sb and As is recognized within a grain of tetrahedrite-tennantite.
The δ¹⁸O values for quartz in Cu-Pb-Zn quartz veins at the Hayakawa deposit range from 1.4 to 3.1 per mil. The value for quartz in Cu-Pb-Zn-quartz veins at the Shakako deposit is 1.9 per mil. The calculated δ¹⁸O values (-10.1 to -3.3 per mil) of ore fluids responsible for the formation of the Hayakawa deposit are lower than sea water and primary magmatic water. Therefore, we suggest that Cu-Pb-Zn quartz veins of the Hayakawa and Shakako deposits originated from ore fluids of meteoric water under a subvolcanic environment.

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