Major and trace element abundances in the <180μm and sand fractions of stream sediments from the Hino River, Tottori, Japan

X-ray fluorescence analyses for major elements and 14 trace elements were made of both the ＜180μm and sand fractions of 103 stream sediment samples collected from active channels of the Hino River，west Tottori Prefecture．Combined histograms of elemental abundances show clear dependence ofcomposition on grain size，with the fine factions containing greater abundances of all elements except SiO_2，K_2O，Ba，Pb，and Rb．Distributions are representative of fractions taken from river sediments，with mainly positively skewed pattetns．Bimodal or polymodal distributions in the sand fractions for a number of elements（Sr，SiO_2，K_2O，Al_2O_3，CaO，Na_2O，and Rb）reflect the influence of local source rocks on composition，as one of the modes is related to samples with catchments draining Mount Daisen．Variation diagrams also clearly display fractionation between the fine and sand fractions．The results show that samples originating from Mount Daisen are the most distinctive，especially with respect to high Sr abundances and relatively low Y，which reflect the adakitic nature of the source volcanics．Intermediate abundances in samples from the lower main channel renect mixing and homogenization of detritus from two areas with contrasting lithologies，felsic granitoids and volcanics to the south，and volcanic products from Daisen to the northeast．Values of Cr are high in the upper reaches of the main channel，reflecting a strong provenance fingerprint from ultrabasic rocks．Abundances of this element then decrease steadily downstream due to dilution from Cr-poor lithotypes．