The whole-rock major element composition of the mylonites in the Kashio shear zone along the Median Tectonic Line in the vicinity of Takato-Ichinose and Kashio, Nagano Prefecture were analysed by X-ray fluorescence spectrometry, together with those of the Hiji tonalites. The mylonites were tentatively classified into three types based on mesoscopic occurrences of feldspar porphyroclasts : porphyroclastic type, fine-porphyroclastic type and fine-grained type. The porphyroclastic type is characterized by coarse-grained feldspar porphyroclasts in a fine-grained matrix containing quartz, feldspar and phyllosilicate aggregates. The fine-porphyroclastic type seems to be well-deformed porphyroclastic mylonites, so that the size of feldspar porphyroclasts is smaller than that within the porphyroclastic type due to intense grain size reduction. The fine-grained type contains only a few feldspar porphyroclasts in a well-banded fine-grained matrix. There exists no systematic difference between the chemical compositions of these three types of mylonites. The SiO₂ contents range from 51 to 73 wt.%. Concentrations of TiO₂, FeO, MnO, MgO, K₂O and P₂O₅ Were proportioned to SiO₂ content but tend to be scattered at SiO₂ > 70 wt.%. The chemical compositions of the Hiji tonalites are indistinguishable from those of the mylonites, consistent with the idea that the Hiji tonalite is a source rock of the three types of mylonites.

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We report 24 radiocarbon ages using the benzene liquid scintillation method developed at Shizuoka University by FUKUHARA et al. (1995).
Benzene was synthesized from buried wood from the Older-Fuji-Mud Flow, charcoals in the Sekotsuji Lava Flow, Kotengu Lava Flow, Fujikawabashi Lava Flow (Mt. Fuji) and Kawagodaira Pyroclastic Flow, and fossil land snail shells (Kikai Island).
The ¹⁴C activity was measured using a low background liquid scintillation counter (Aloka-LBl) at the Radiochemistry Research Institute of Shizuoka University. Beta decay from benzene with respect to the standard and background with a window between 150 and 550 channels were detected every 20 minutes and repeated 73 to 225 times to obtain a sufficient count for statistical error estimation.
Correction for δ¹³C value was carried out. The standard used was NIST oxalic acid SRM 4990C, and the half-life used was Libby’s half life.
The ¹⁴C ages of buried woods and charcoals of Fuji Volcano were between 1,240 ± 80yr. B.P. and 27,900 ± 600yr. B.P.
The ¹⁴C ages of charcoal in the Kawagodaira pyroclastic flow was 2,900 ± 110yr. B.P..
The ¹⁴C ages of fossil land snails of Kikai Island were 29,800 ± 400yr. B.P. and 3,910 ± 60yr. B.P..

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Geologic classification and distributions of the effusives of Fuji Volcano were com-piled mainly based on Tsuya (1968, 1971) and the framework of geologic age by Miyaji (1988). The effusives can be classified into those of the Ko-Fuji and Shin-Fuji Volcanos, and that of the Shin-Fuji Volcano can be divided into 3, old, middle and young. The age of the boundary between the old and middle of Shin-Fuji Volcano is ca. 6300 years, and between middle and young is ca. 2200 years. The enormous amount of effusives of Fuji Volcano is related to the collision tectonics in central Japan, induced by motion of the Philip-pine Sea Plate.
Paleomagnetic samples were collected from 11 sites of the old lavas and 3 sites of the middle aged lavas of the Shin-Fuji Volcano. Three oriented blocks were sampled from each site. The intensities of natural remanent magnetization (NRM) of most of the samples ranged from 5 to 25 A/m, and median destructive field (MDF) was 15–40 mT. The direction of stepwise demagnetized NRM is stable and can be used for paleomagnetic studies. The positions of the virtual geomagnetic pole (VGP) are distributed around North Pole within latitudes higher than 60°N. VGP distributions are significantly different for the sites on the “same” lava. NRM intensities, MDF, anisotropy of magnetic susceptibility, and anhysteretic remanent magnetization (ARM), are useful to characterize the rock magnetism of lavas.
The 3 blocks from 2 sites of the middle aged lavas of the Shin-Fuji Volcano have extremely strong intensities ranging from 40 to 80 A/m and different rock magnetic character from the other samples with 5–25 A/m of a NRM intensity. The sampling sites are located near the lower margin of the lava flows. The strong NRM can be estimated by the precipitation of reduced iron in the lava flow, contaminated by growing vegetation.

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X-ray fluorescence analysis (XRF) is one of the easiest and most rapid analytical methods that can be used for major and trace element analyses of rock samples. This paper presents an analytical technique for major elements in rock samples by XRF.
Grinding experiments were done by the planetary ball mill Fritsch P-5,and granodiorite and andesite were used as hard and less hard samples. First, samples were crushed into small pieces (< 4 mm in diameter). Approximately 20–25 g of samples were set in containers made of tungsten carbide (WC) and agate. A rotation speed of 200–300 rpm and a grinding time of 20 min yielded rock powders with an average grain size of 3.7–8.4 µm and a dispersion of 11.7–122 µm² for WC containers, and an average grain size of 5.9–6.2 µm and a dispersion of 34.8–69.2 µm² for agate containers. However, agate containers could not grind granodiorite samples completely.
Rock powder was fused into a glass bead by a glass-bead sampler Philips THG-5. The rock powder was put into an oven and dried overnight at 110°C. The mixing ratio of the sample:flux was chosen to be 1:10 to reduce matrix effects and 0.5000 g of the sample and 5.000 g of Li₂B₄O₇ were weighed and put into a Pt cup. After trial and error, the most suitable conditions of fusion were determined.
To correct for variations in X-ray intensity, three corrections were made: monitor and drift corrections to adjust the temporal variations for long and short periods, and a bead correction to cancel variations arising from the roughness of the bottom of the Pt cup. Among these, the drift correction was found unnecessary because of the stabile X-ray intensity during the measurement. The bead correction is expected to be useful, but its effect could not be confirmed.
36 samples ranging in composition from basalt to dacite were analysed by XRF machines of Shizuoka University and the Institute of Earthquake Research, University of Tokyo. Both gave consistent results with relative errors of ± 5% for SiO₂, TiO₂, Al₂O₃, Fe₂O₃, MgO and CaO. The relative errors are less than ± 10% for MnO (> 0.1 wt%), Na₂O (> 2 wt%), K₂O (> 0.5 wt%) and P₂O₅ (> 0.2 wt%).

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A newly developed technique for analyzing trace amounts of Nb and B in rock samples is described. Samples were decomposed using HF-mannitol method. Nb and B were chemically separated from the major cations using ion-exchange chromatography and then measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES) with analytical lines of 269.706 nm and 249.773 nm, respectively. In the whole analytical procedure, recovery yields of these elements were 97 to 100% and procedural blanks were undetectable. Detection limits of Nb and B were both 0.1 ppm in rock when 0.5 g of sample was used. Nb and B concentrations determined for GSJ rock reference samples showed good agreement with the recommended values, and the analytical errors were less than 5%. The present, method enables us to precisely determine the B/Nb of various rocks, which is especially useful for elucidating subduction zone processes.

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Rain water contains various insoluble particles. Detection and observation of in-soluble organic particles in rain water with a fluorescence microscope has been studied. A laser scanning microscope was used for observation of fluorescent particles. Rain water was collected from July 1996 to December 1996 in Shizuoka, and 17 rain water samples were collected. Fluorescent particles in rain water were characterized as organic matter using a Fourier transform infrared (FTIR) microscope. It was found that about 90% of fluorescent particles in rain water were organic matter and about 70% of non-fluorescent particles in rain water was inorganic matter, and also it was found that some of fluorescent particles were biological particles. These results indicate that most fluorescent particles in rain water reflect organic particles. Some fluorescent particles in rain water are cedar pollen and pine pollen, but the compound or material of majority couldn’t be identified. The mean concentration of fluorescent particles with radii 2 µm ≦ r < 128 µm in rain water was 960 cm⁻³. The number of fluorescent particles in rain water was influenced by the amount of rainfall and wind speed, and the some cases is also influenced by rainfall intensity.

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Cosmic ray produced ³²P (t_1/2 = 14.3 days; E_max = 1.71 MeV) is a powerful tracer of physical and biological processes and the short time scales of atmospheric and upper ocean P cycling. In spite of their tremendous potential for tracing processes involving phosphorus in the environment, the very low activities in nature have impeded their use in biogeochemistry. In order to determine the low-level beta activities of ³²P in nature, sample concentration and/or extraction from large volumes of samples are required with a low-level β counting in the field. Preconcentration of the activity in aerosol is achieved here by various concentrating methods. Low-level β counting is achieved by liquid scintillation counting and low background counting. The result of measurement of the activity in aerosol by liquid scintillation counting at Shizuoka University (34°58'N, 138°24'E) ranged from 0.0010 ± 0.0002 to 0.003l ± 0.0002 dpm/m³ (dpm: disintegrations per minute). Decay-curve in low background counting confirms the existence of ³³P (t_1/2 = 25.3 days; E_max = 0.25 MeV).

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