抄録
The bromine and iodine contents were determined simultaneously by neutron activation analysis on two boreholes of the Tertiary marine siltstones and marine tuffs collected from Tomioka, southwestern Gunma Prefecture, and the relationship between these elemental contents and the organic carbon content was investigated. The arithmetic means of the bromine and iodine contents of siltstone samples were 1.9ppm and 2.0ppm, respectively. Tuff samples gave averages of 0.69ppm for the bromine content and 0.75ppm for the iodine content. The positive correlations were observed between the halogen contents and the organic carbon content of the sedimentary rocks analyzed. This suggests that the bromine and iodine in the sedimentary rocks originate from marine plants and microorganisms incorporated during sedimentary processes.
