Abstract
Amino acids in solution are adsorbed by Miocene argillaceous rock fragments which contain clay minerals of mica-smectite mixed layer. The order of the adsorption is as follows; lysine > glycine > alanine > valine, leucine > aspartic acid. Since basic amino acids are selectively adsorbed in the rocks, the amino acid composition could not be an indicator for determining the depositional environment, contrary to the studies of Sasaki (1978, 1974).
