The Nature of Organic Matter in Sediments

Abstract

While biologists, oceanographers and those concerned with early diagenesis are mainly interested in the labile organic fraction that is consumed prior to burial, most geologists focus their attention on the much smaller fraction that survives diagenesis to become a potential source of hydrocarbons. However, the significance of the general terms ‘refractory’ and ‘labile’ (what is, or is not, degradable) depends very much upon one’s viewpoint and working time-scale. The views expressed in the literature reflect the differing perspectives of the laboratory, modern surficial sediments and geological timescales (that is, from hours to millions of years). Many of the short-term observations made in the laboratory and on the upper few tens of centimetres of Recent sediments are of limited relevance to long-term geological considerations of carbon burial and source rock potential.