Abstract
Paleozoic-Cenozoic sedimentary rocks from the Chugoku and Shikoku districts contain 1.5-3.5 ppm tin in general (avg. 2.4 ppm, n=179). Those occurring near Paleozoic limestone plateau in the Chugoku district, and containing mafic volcanics are much lower in tin, reflecting their tindepleted source materials. Shales from the chert-dominant strata in Ota-gawa area give highest values for tin (3.8-6.4 ppm) and potassium oxide (3.8-4.9%). Most of the tin may be transported in the form of particulate together with fine sediment fractions during the weathering. Thus, tin is more abundant in the shales and slates than sandstones.
Compared with Recent sediments collected from the lakes and sea areas from the Japanese Islands to Central Pacific, tin contents of sedimentary rocks are more or less similar to those of the lake sediments (2.5 ppm, n=70). The Recent marine sediments have much lower values in tin (1.5 ppm, n=193). Tin is distributed more abundantly in the terrigenous environments than in the oceanic ones.
