Pioneer results of the comprehensive analysis of nodules from the Upper Paleozoic coaliferous association and the underlying Middle Paleozoic sequence in the southern Tunguska Basin (Siberian Craton) suggest the following: (1) sediments underlying the coaliferous association contain two (siliceous and carbonate) types of normal nodules and one type of allogenic nodules (redeposited chalcedony nodules in the kaolinite-chalcedony unit of the Beloyarsk Formation); (2) the coaliferous association includes four (calcite, siderite., pyrite, and goethite) types of nodules; (3) each nodule type is confined to a specific genetic type of sediment; e.g., siliceous nodules are confined to lagoonal sediments; calcite nodules, to lacustrine and lacustrine-boggy sediments; siderite nodules, to lacustrine-boggy and boggy sediments; pyrite nodules, to boggy sediments; and goethite nodules, to alluvial sediments; (4) the formation of goethite nodules is mainly related to the erosion and redeposition of siderite nodules; (5) the coefficient of carbon concentration shows a distinct positive correction with the coefficient of nodule content; (6) nodules appeared in the coaliferous association during diagenesis and epigenesis; the calcite and pyrite nodules are enriched in sandy material, as suggested by the high content of insoluble residue; (7) combustion of coal seams promoted the melting of the adjacent siderite nodules and the formation of magnetite ores; consequently, the thermally altered mudstones, siltstones, and sandstones were transformed into a high-quality building material that is used as road fill.
