Clay Fabric and Environment

Abstract

The clay microstructure of flocculated, suspended sediments and of sedimentary deposits depends on a long series of geologic and/or oceanographic processes and events, and on the types of source material available, and on the environmental setting. These processes and factors produce primary and postdepositional sediment properties in time and space. The primary depositional properties include textures, mass physical and mechanical properties, and soil state (fluid-plastic-solid), and they are determined by particle size, mineralogy, particle size distribution, and microstructure. As such, the microstructure is a critical element in determining the fundamental properties of aeolian, fluvial, lacustrine, terrestrial, and submarine deposits. Sedimentary particles, detrital and biogenic, interact in response to mechanical and electrical forces during transport to depocenters. These forces are important in determining the fabric of the transported material and the freshly deposited sedimentary material. Deposited particles establish the primary properties of the sediment. Once deposited, postdepositional processes come into play. Postdepositional processes and effects can be grouped into three major categories—biogeochemical, physical- mechanical, and mechanical (fig. 5.1, Bennett and Nelsen 1983).