Chapter 27 - Coal deposits of the Newark rift system

Abstract

Detailed biostratigraphic analysis, updated knowledge of the subsurface, calculation or recalculation of resources using updated distribution data, and reinterpretation of depositional environments using data from modern swamps of active rifts have been applied to the coal deposits of the Newark rift system. Bituminous coal mined from Newark rift-system basins played an important role in the early economic history of the United States. More than ten million short tons were mined from the Richmond and Deep River basins, and our resource estimates suggest that about 4 billion tons of coal remain in the Richmond, Deep River, Dan River-Danville, Farmville, and Taylorsville basins. However, the coal beds are faulted, dips are steep, methane explosions have been a major factor in loss of lives, and the sulfur content of many beds is high. For these reasons, the coal probably never will be mined again, even though methane may be a future economic resource. The dominant plants found in the coal beds are horsetails, quillwort-like plants, and cycadeoids. A characteristic suite of palynomorphs including Calamospora nathorstii, Convolutisporites affluens, Cyclotriletes oligogranifer, Tigrisporites dubius, Colpectopollis ellipsoideus, Plicatisaccus badius, ‘Placopollis raymondii’ (Koob, 1961), and Cycadopites ‘sp. 103’ (Cornet, 1977) in the coal beds and associated carbonaceous shales shows that the main stage of peat accumulation occurred during the middle Carnian age of the Late Triassic (as used by Cornet, 1977). The environments in which the Late Triassic peat accumulated are typical of those around modern rift lakes. River delta swamps, lake fringe swamps, and the filling-in stage of lake death swamps appear to have been the most important depositional environments.