『Abstract
　Geochemical mapping of Shikoku in the SW Japan Arc was conducted using stream sediments (＜0.18 mm fraction) with sample densities of 1 site per 106 km². Concentrations of 51 elements in 173 stream sediments were determined. Areas with especially high Cr, Ni, Mg and Co concentrations run intermittently and linearly through Shikoku, and coincide with exposures of the Mikabu greenstone complex composed of oceanic basaltic and gabbroic rocks with minor ultramafic bodies. Areas with higher concentrations of Fe, V, Sc, Ti, Mn, Cr, Ni, Mg, Co and Eu are distributed widely along the Shikoku Island axis; they mainly overlap with the zones of the high-pressure type metamorphic rocks (Sanbagawa Belt) and the Jurassic accretionary complexes with sedimentary rocks (Chichibu Belt): in contrast, areas with lower concentrations spread over the northern coastal zone of Cretaceous granitoids (Ryoke Belt) and in the southern coastal zones of Cretaceous-Paleogene accretionary complexes (Shimanto Belt). Distribution patterns of these elements reflect that various amounts of mafic and ultramafic materials, possibly of oceanic origin, are associated with the rocks in the Sanbagawa and Chichibu Belts, although such components occur sparsely in the Shimanto and Ryoke Belts. Calcium, Sr, Na, Nb, Sm and Gd contents are lower along the southern coastal zone. High values of Th, U, La, Ce and Ba are associated with granitic rocks. The positive anomalies of Cu and Cd coincide with the distribution of stratabound Cu deposits in the Sanbagawa Belt. Positive anomalies of Sb in the northern area are associated with Sb deposits near the large Median Tectonic Line fault zone. A high-Hg zone is present in the southern fore-arc area. The median concentrations for stream sediments in Shikoku are higher in Hg, Cu, Ni, Cr, Rb, Li, Cs, K, slightly higher in Nb, Ta, La, Ce, Sn and lower in Ca than those for average Japanese stream sediments. The median concentrations for the four geologic zones show systematic wide variations of mafic associated elements, and narrow variations of lithophile elements generally more abundant in felsic rocks. The chemical compositions of the stream sediments in Shikoku largely reflect the concentrations in the pre-Neogene accretionary complexes and in the high-P metamorphic rocks mainly formed from clastic materials derived from continental margins, and ratios of mafic and ultramafic materials within surface rocks; they are partly influenced by sulfide mineralization and fluid migration.』

1. Introduction
2.Geological setting
3. Samples, analyses and map presentation
4. Results
　4.1. Chemical compositions of the stream sediments from Shikoku
　4.2. Geochemical maps
　　4.2.1. Siderophile and lithophile elements abundant in mafic rocks
　　4.2.2. Lithophile elements abundant in felsic rocks
　　4.2.3. Chalcophile elements
　4.3. Chemical variations related to the geologic zones
5. Discussion
　5.1. Variations of siderophile and lithophile elements and their origin
　5.2. Variations of chalcophile elements and their origin
　5.3. Regional geochemical characteristics
6. Conclusions
Acknowledgements
References

Fig. 2. Geological map of Shikoku with sample localities. (1) Quaternary sediments, (2) Tertiary volcanic and sedimentary rocks, (3) Cretaceous sedimentary rocks, (4) Silurian.Jurassic sedimentary rocks, (5) Paleogene accretionary complex, (6) Cretaceous accretionary complex, (7) Jurassic accretionary complex, (8) Permian accretionary complex, (9) metamorphic rocks (low-P), (10) metamorphic rocks (high-P), (11) felsic plutonic rocks, (12) mafic plutonic.volcanic rocks, and (13) ultramafic rocks. Fig. 3.1. Elemental distribution maps of Shikoku for T-Fe2O3, TiO2, V, Sc, CaO and MnO. Boundaries of the geologic zones in this study are shown with broken lines. Distribution of rocks is from the Geological Survey of Japan (1992, 2003). Mikoshiba et al.(2011)による『Geochemical mapping in Shikoku, southwest Japan』から