ELECTRON MICROSCOPY INVESTIGATION OF THE MICROSTRUCTURE IN SEDIMENT SAMPLES FROM THE GULF OF MEXICO.
TEXAS A AND M UNIV COLLEGE STATION DEPT OF OCEANOGRAPHY
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Sediment samples were taken from Gulf of Mexico cores. From these samples smaller ones were cut, freeze-dried and impregnated with Maraglas, an epoxy resin. Ultrathin sections of the impregnated samples were cut, and viewed in an electron microscope. Micrographs of the ultrathin sections revealed that the microstructures of most of the samples had a loose, open, random arrangement of particles. Differences in appearance of some of the microstructures are attributed to grain size variation, desiccation, remolding, and shearing of the sediment. Associated with this last factor is the formation of oriented domain structures. Variations among the samples in depth of burial, rate of deposition, and, particularly, clay mineralogy were generally small and resulted in no obvious differences in their microstructures. Cohesion, water content, and consolidation characteristics of samples were found to be generally indicative of the type of microstructure observed. Laboratory consolidation and desiccation of samples caused a collapse of the microstructure and preferred, as well as non-preferred, orientation among the particles. Remolding of a sediment resulted in clumping of the particles, parallelism among the particles, and large voids. No evidence was observed in the micrographs which would substantiate the existence of a precipitated chemical cement. Author
- Physical and Dynamic Oceanography