Conceptual scientific models of clay and clay fabric development can be constructed profitably by considering chemical and physical systems in terms of an ordered hierarchy. We develop here a hierarchical model of early stages of marine sediment development identifying processes and focusing on mechanisms. While the focus of our model is on mechanisms, the physical aspects of the hierarchy are cast in terms of the nanometer (nanofabric) level of organization of sediment fabric. This level is nested below the micrometer (microfabric) level that includes aggregates of clay signatures and is nested above the molecular level that includes edges and faces of clay layers characterized by atomic, ionic, and molecular organo-clay interaction. The model provides a vehicle for identifying mechanisms with the spatial levels at which they operate in order to understand the interactions of these mechanisms both within and across these levels. For example, electrochemical mechanisms that affect the assembly of clay layers and multi-layers operate at the molecular level manifesting as covalent and ionic bonding, London-van der Wal's attraction, and very short range Born repulsion. In contrast, the mechanisms of interface dynamics operate at nanometer to micrometer spatial levels of organization. These mechanisms include mass fluid flow, laminar flow, and shear forces of micro-turbulence. In fact, the rates and types of mechanisms operating at each level in general hierarchical modeling typically do not form a continuum across spatial scales, but rather are qualitatively distinct and seem to operate in discreet and natural ranges within each spatial level. A hierarchical model can enhance understanding of this complex interplay of mechanisms and delimit the dominant mechanisms and processes during the formation of organo-clay mud-to-shale during their great planetary cycles.
Curry, K. J.,
Bennett, R. H.,
Smithka, P. J.,
Hulbert, M. H.
(2009). Hierarchical Modeling: Biogeochemical Processes and Mechanisms that Drive Clay Nano-and Microfabric Development. .
Available at: http://aquila.usm.edu/fac_pubs/75