PETROGRAPHIC CHARACTERISTICS OF COAL AND COAL FACIES ANALYSIS OF THE UPPER MEMBER OF THE LATE PERMIAN COAL FORMATION IN TIANBA AND TUCHEN

The upper member of the Late Permian coal formation is a set of shallow water delta deposits in studied area. The sedimentary environments of the coal seams belong to three facies. In the upper member of the coal formation there are ten coal seams and the main seams are number 3. 6 and 12. The layers of the coal seams are stable. Their thickness varies obviously and the structures are from simple to complex. The anamal and plant fossils are contained both in seam tops and floors. There is 1-2 clayrock with cash in the seam. The coal seams contain: water (W^f) 0.81-2.47%, ash (A⁸) 9.16-26.42%, volatile (V^r) 26.47-41.63*5, gelatinlayer (Y) 8.0-42.5mm, the total surfur content (S_Q⁸) 0.103-3.935%. The R⁰max of the vitrinite (0.76-1.11%,) shows that the metamorphic grade of the coal is II-IIIstage. The coal -forming matters are mostly gelatificated, so that thick cell-walls are common. The maceral mainly consists of the nonstructural gelatinized matrix and vitrain. Barkinite, cutinite and sporinite are commonly seen. Fusain and xylovitrain-fusain are locally gathered as lens. Also there are a certain amount of transitional macerals in the coal. All of the macerals can be found in broken and crumbled occurences ect. The occurcnces of mineral impurities in the coal which assume as clastic, nodular, filled and lenticular forms are comples and variable. The peat swamp facies which formed the main coal scams are unstable environments covered by relatively deep water, in which the water level and medium properties are changable. The peat swamp faeies in the studied area belong to two types of coal facies: The upper delta facies and the coalffacies from upper-lower delta transitional zone to lower delta. In accordance with genetical marks, The peat swamp facies can be subdivided into eight kinds. The coal seam number 3 is a good example to show the characters and changes in the peat swamps facies as it was forming.