Phyterals of humic coals in the U.S.S.R.

Abstract

The results of a study of plant remains found in coals of Devonian to Neogene age, which were studied mainly by the method of phyteral analysis, are presented. Most of phyterals discussed and illustrated in this paper are from coal basins in the U.S.S.R. However, a discussion of occurrences of phyterals in coal basins worldwide is also included. Middle Devonian coals contain fungal remains and phyterals of the enigmatic vascular plant Orestovia. The most characteristic phyterals of Euramerican Carboniferous coals are the following: periderm of stems and rhizomes of lepidophytes, wood and cortex of gymnosperms of uncertain systematic position, rachides of pteridosperms, and fructifications of spore-bearing plants. Vitrinized phyterals predominate over fusinized phyterals in Carboniferous coals. In Permian coals of Gondwana and Angarida, vitrinized and fusinized woods, bark tissues and leaves of pycnoxylic gymnosperms are characteristic phyterals. Differences in phyteral composition of Early and Late Permian coals indicate that phyterals from vitrinized leaves were more dominant in Late Permian coals. Triassic coals rarely contain phyterals of known affinity. Jurassic and Early Cretaceous coals are similar in phyteral composition. Periderm and cork of conifers and ginkgoaceous plants are typical phyterals. Phyterals of vitrinized and fusinized gymnospermous wood played a significant role in these coals as well. Leaf phyterals usually compose layers of the paper and “fall-of-leaves” coals. Distinctive characteristics of phyteral composition of Cenozoic coals are: (1) wide distribution of lignitized woods; (2) constant presence of well identified and very specific root remains; (3) high content of plant attritus; (4) commonly occurring and distinctive fungal phyterals. Further study of coal phyterals is suggested for correlation of coal seams and coal-bearing strata and for the prediction of coal quality.