2007 年 22 巻 p. 31-42
The chemical compositions of woody fossil fragments collected by picking manually and density centrifugation from sandstones of the Lower Cretaceous Yezo Group in Oyubari, central Hokkaido, Japan were analyzed by KOH/methanol hydrolysis (saponification) after solvent extraction. Organic compounds bound in macromolecules of the woody fragments with ester bonds, obtained by saponification, were mainly composed of short-chain (C14 to C18) fatty acids and series of n-alkanols ranging from C12 to C28 homologues. These ester bound constituents are attributed to moieties of polyester parts of selectively preserved resistant macromolecule like cutin or suberin. Even carbon-number predominance was observed in both compounds, which indicated that biological components were well preserved. The bound fatty acids showed similar distribution patterns among all samples, indicating that these moieties might have been altered by strong diagenetic processes. On the other hand, the distribution patterns of n-alkanols significantly varied. In particular, those of long-chain (>C20) n-alkanols varied possibly depending on plant taxonomy. Thus, we suggest that these parameters are strongly useful as molecular paleobiological indicators for chemotaxonomic analyses. Also, the distributions of short-chain n-alkanols and the ratios of short to long-chain homologues are presumably useful indicators for diagenesis, taphonomy and environment.