Investigation of the origin and sedimentary environment of marine sediments from coastal areas of western Japan by INAA

Trace elements such as Sc, lanthanoids, Th and U were determined by means of instrumental neutron activation analysis (INAA) in marine sediment core samples collected from 5 coastal areas in western Japan mainly facing the Pacific. The origin of the coastal sediments and the sedimentary environment are discussed in terms of such parameters as the La*/Lu* and Ce*/La* ratios, the Th/Sc ratios and the Th/U-Ce/U plot obtained from the analytical data. In particular, it was confirmed that the Th/U-Ce/U plot introduced in this work is extremely useful for estimating the sedimentary environment, including redox conditions.