1981 Volume 90 Issue 4 Pages 225-234
Since the end of the second world war, coal and petroleum geologists in Japan have worked in different ways. To rehabilitate devastated japanese economy, prime importance was given to the increase of coal production which necessitated opening of new mines and development of new areas, until then remained undeveloped mostly because of unfavorable geological condition, therefore, this activated coal geology including coal petrology, and, geologist was required to submit more detailed and pragmatic geological informations to mining engineer, which rendered him to be inclined to mining geology than pure or academic geology.
On the other hand, petroleum geologist, confined in small oil fields in Japan for nearly 20 years, was obliged to learn in literature new conceptions advanced abroad after war years, such as sedimentary basin, sedimentology, subsurface geology, etc. Consequently, his interest inevidently parted from detailed geology and tended to pure geology, resulting the loss of conversation between coal and petroleum geologies. However with increased concern on appraisal of maturity of resource rock, geochemist found out in early 1970s the existence of parallelism between maturity of kerogene and coalification, and that reflectance of vitrinite, of which studies were advanced by coal petrologist especially in last twenty years, is a good indicator for determination of maturity.
This new geological (optical) method will allow petroleum geologist to have say not only on maturity, but also on maximum depth of subsidence, tectogenesis and geothermal history, if it is carried out pertinently.
The author emphasizes the necessity of full partipation of experienced coal petrologist with sufficient knowledge on macerals and coalification, (in petroleum exploration, ) because vitrinite in sedimentary rock is poor in volume and sometimes not easy to pick out true vitrinite from other resembling organic materials.