Organic matter sequestered in potential energy fields predicted by 3-D clay microstructure model: Direct observations of organo-clay micro- and nanofabric

Transmission Electron Microscopy (TEM) observations confirm theoretical predictions of the location of organic matter (OM) sequestered in fine-grained sediment. Organo-clay micro- and nanoscale fabric images validate for the first time the protective adsorption model of OM preservation. Preservation of OM against enzymatic digestion is demonstrated predominately at locations consistent with our model of the potential energy field that is developed through interactions of clay minerals, the OM, and pore water chemistry. Pores observed in 2-D fabric TEM images of clay muds commonly appear to be totally encapsulated. However, the great majority of these pores are clearly demonstrated to be open in one or more directions when observed in rotated 3-D images. Despite the scarcity of completely closed pores, OM is preserved against enzymatic attack in those locations where the predicted 3-D potential energy of interaction between clay domains and OM is attractive.

► TEM images of clay sediment confirm OM preservation consistent with model.
► Prediction of sequestered OM at high interaction-energy clay domain sites: supported.
► As observed, OM is protected against enzymatic attack at clay fabric signatures.
► Most pores are open in multiple directions: observed in rotated 3-D fabric images.