The vertical and lateral changes of vitrinite reflectance, sporinite fluorescence and maceral content were studied concerning the Honso coal seam of the Harutori coal-bearing formation at the Taiheiyo coal mine. There is inverse correlation between vitrinite reflectance and degradinite content. That is to say, concerning the lateral change of vitrinite reflectance, vitrinite reflectance shows low at the center of the coal basin where degradinite content is high, but it is gradually getting higher and higher toward the margin of the basin while degradinite content is getting lower and lower. Concerning the vertical change of vitrinite reflectance has also inverse correlation with degradinite content. That is to say, vitrinite reflectance shows high when degradinite content is low, while on the other hand vitrinite reflectance shows low when degradinite content is high. Contrary to the case of vitrinite reflectance, sporinite fluorescence does not show any definite correlation with vitrinite reflectance and degradinite content respectively. As a result, the lateral variation of maceral component is supposed to represent the difference of plant communities which are closely associated with physical and chemical properties of vitrinite producing effect on vitrinite reflectance. Near the margin of the original swamp of the coal basin, trees and shrub were rich in woody tissue which were transformed to be vitrinite showing high reflectance after undergoing coalification. On the other hand, near the center of the swamp reed plants poor in lignin were dominated, which were transformed to be vitrinite showing low reflectance. On the other hand, nearly similar assemblage of spores and pollens were supposed to be distributed in swamp irrespective of depositional environment, because they mingled and spread while flying in the air. In spite of the fact that sporinite fluoerscence depends upon types of spores and pollens, sporinite fluorescence shows nearly same within certain limited geologic time and area. In that sence, sporinite fluorescence is more reliable parameter as coalification degree rather than vitrinite reflectance.
In this paper, as a series of studies concerning the origin of petroleum in carbonate rocks, various problemes on the time and conditions of generation, migration, and accumulation of oil from carbonate sediments are discussed and the present author's opinions concerning those problemes are given.
Dramatically changing geophysical techniques are overviewed. In recent years, because of the well known big exploration surge for oil and gas, every explorationist has been forced to clarify almost all types of petroleum traps. Seismic reflection method has been the most extensively improved to delineate more precise three dimensional (3-D) subsurface structures and to obtain 3-D well-log-like infor-mation. One of the outstanding features is a ever increasing computer utilization for the full processing of seismic data. Besides seismics, standard geophysical methods, gravity and magnetic, are also effectively used. In addition to these, greatly improved new MT method has become a powerful tool at various areas with thick volcanic cover and/or of extremely complex geology.