Early Diagenesis of Sedimentary Lipid Constituents in Small Lake

Philip A. Meyers, Eileen S. Ho, Chris Sutton

Sedimentary lipid constituents have been obtained by extraction and by pyrolysis of dated intervals of a sediment core from a small pond on Coburn Mountain, Maine. The core represents the last 200 years of sediment accumulation, yet diagenetic effects are evident in lipid compositions, even though bulk organic carbon appears to be preserved well. From odd/even and long/short ratios, extractable fatty acids appear to undergo substantial postdepositional alteration. Fatty alcohols experience moderate amounts of diagenesis, with some production of secondary n-alkanols being evident. Aliphatic hydrocarbons are least modified and retain much of their original source character. Long-chain components reflect the importance of watershed land plants to the sediment lipid content, nd the small contribution of pristane is consistent with the faunal assemblage of the lake. Pyrolysis products of bulk organic matter indicate increasing condensation into macromolecular forms with greater age of sediment core intervals. Compositional changes are not otherwise consistently related to sediment age, indicating that conditions at the sediment-water interface at the time of burial control of the ultimate character of the lipid contents of these organic carbon-rich lake sediments.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.