No abstract

The paper presents the results of coal petrographic and geochemical studies of the Tutleim Formation rocks organic matter in the area of the Em-Egovskaya summit. Five macerals were identified that compose the organic matter of the studied formation: “standard” bituminite, “atypical” bituminite, radiolarian organic matter, alginite and vitrinite, as well as bitumen and bitumen films, which are the products of the original organic matter transformation. The metamorphosis in macerals during catagenesis is described, and the order of their entry into the generation phase is established. It has been shown that alginite starts transforming first, then “standard” bituminite, “atypical” bituminite, and the last one is the radiolarian organic matter. The results obtained were confirmed by the laboratory modeling of the further organic matter transformation. New bitumens are formed with different fluorescent properties compared to the initial ones. The results obtained in combination with the study of changes in the composition of both macerals and bitumen can make it possible to assess the contribution of individual organic matter microcomponents to the process of petroleum hydrocarbons generation.

The question of the correct terminology is highly relevant, since researchers should understand one another in communication with specialists in different branches of geology. An overview of the terms already existing in the English-speaking world for describing oil-prone macerals, such as alginite, bituminite, bitumen, solid bitumen, pyrobitumen, oil, was presented, and it is more convenient to combine all zooclasts into bioclasts, since it is not always possible to determine whether the remains belong to the animal or plant world. Particular difficulties emerged with the term “bitumen”, which in Russian has two meanings. Increasingly, the films between mineral grains can be named both bitumen and oil. It was also suggested to divide bituminite in pre-mature bituminite, mature bituminite and post-mature bituminite in order to emphasize the features of those transformations that occurred with the initial organic matter during thermal maturity. Due to the fact that in the process of thermal maturity, the reactive part of kerogen = bituminite will transform into a liquid and gas, its solid part (“residual organic matter”) was suggested to be called solid bitumen or pyrobitumen.