Geological Basis of Coal Occurence and its Nature

Abstract

Because the coal is composed of several macerals which altered in multifarious grades during the coalification process divided into two stages, bio- and dynamo-chemical one, coals of really manifold physico-chemical natures turn up, according to assemblage of macerals and to degrees of their alterations. Due to recent artificial coalification experiments dynamo-chemical process is governed primarily by temperature and the time during which plant materials were heated, and pressure retards such reactions.The same maceral in the same coal seam must have experienced the same dynamochemical reaction through the geological progress, it is, therefore, hardly possible to explain existences of the same macerals having different physico-chemical properties, and also of vitrinite and fusinite which are originated equally from woody materials. Intensity of degree of alteration of maceral in the biochemical stage must be accordingly evaluated more seriously.As biological reactivities in this stage are essentially influenced by geographical and geological circumstances of the depositional basins like as location or movement of the basin, height or nature of ground water, etc, occurence of coal basin is discussed from geotectonical point of view, and coalification process and resulted natures of coals in respective type of basins are also mentioned.From such discussion and consideration, characteristic nature of Japanese coal may be quite well understood.