ABSTRACT

Analysis for purines and pyrimidines was carried out with Neogene sediments in a 1600 m thick stratigraphic sequence in the Shinjo basin. Adenine, guanine, thymine, and cytosine were detected at the 100 ng/g level in the top sediment of the sequence, while guanine and occasionally adenine were chiefly detected at the 10 ng/g level in the remainder of the sediments. The assemblage of these nitrogen bases and their amounts are quite different from those found in recent sediments. These characteristics indicate that the nitrogen bases recovered survived diagenesis and are indigenous to the Neogene sediments.