POTENTIAL FOR AMORPHOUS KEROGEN FORMATION VIA ADSORPTION OF ORGANIC MATERIAL AT MINERAL SURFACES

The traditional model for the formation of kerogen in sediments is that biopolymers undergo biochemical degradation, followed by polymerization and condensation, resulting in an insoluble product. An alternative method of kerogen formation has been postulated, based on observations that certain biopolymers may be highly resistant to microbial degradation, indicating that these components can be selectively preserved. Clay minerals have strong adsorption and catalytic properties, with a high effective surface area, and are commonly abundant components of organic-rich sediments. Hence, clays are likely to adsorb organic matter in sediments. Following mineral dissolution of a sediment, clay-adsorbed organic material may give rise to an insoluble polymer, which would possess many of the characteristics of amorphous kerogen. Although the quantitative importance of clay adsorption as a vector of carbon preservation is currently unclear, in certain environments this process could account for the formation of amorphous kerogen.