Prediction Model for Compositional Changes within Coal from Core Data. Quarterly Report, July--September 1978

摘要

The salt water marsh area at Wallop's Island, Virginia, represents restricted back barrier environment that extends almost continuously from Ocean City, Maryland to Florida. The environment is not a coal forming type swamp; it is a salt water marsh. However, it does have many of the basic geologic, geochemical, and physiologic of a peat swamp. The mechanisms of pyrite and clay mineral formation within this environment are thought to be the same as those of the coal-type swamps and offer therefore an excellent natural laboratory for the initial study. Sediment samples were collected from a variety of environments including the relatively open, marine-dominated bays, the more restricted, shallow bays (still marine dominated), the marsh surface, and the estuary channels of streams flowing off the mainland. The chemistry of the waters in all the areas was quite similar; all areas were marine dominated. The basic mineralogy of the bottom sediments was similar in all sites except in the more open bay. Most significant was the presence of pyrite. The last significant finding was that the plant materials collected contained mineral matter and that the composition of the mineral matter was the same as that of the accumulating sediment except for the presence of abundant pyrite. The plant materials were thoroughly washed of all adhering sediment so that the mineral matter observed was not that collected on the plant's surface but came from within the plant. This supports the theory that a significant portion (and perhaps a major portion) of the mineral matter in coal is not clastic in origin derived from the surrounding landmass, but rather has its origin in the plants themselves and that the concentration of ash in a coal is therefore a combination of what plant types contributed to the original peat plus the degree of chemical degradation to which the original plant materials were subjected after burial. (ERA citation 04:040124)