Springfield Coal Geology Near Galatia Channel at Wabash Underground Mine

Marvin B. Thompson

Regional exploration of the Springfield Coal during the 1960s indicated underground minable low-sulfur coal adjacent to the Galatia channel in southwestern Indiana and southeastern Illinois. The AMAX Coal Company Wabash Mine, located near Keensburg, Illinois, commenced production in 1973. Mine development has since spread south of and alongside the main channel body over a distance of approximately 5 mi. Mining has proven the early regional exploration mostly accurate. As predicted, coal thickness increases and sulfur content decreases near the channel where the overlying Dykersburg Shale Member thickens.

Understanding the common depositional history of the Galatia channel, Springfield Coal, and Dykersburg Shale Member roof has been a key to successful mine planning. Shale partings within the coal and elongate roof rolls locally protrude from the channel and impede mining. Within the mined area, the Dykersburg Shale Member varies from a weakly laminated sandstone-shale roof, to a homogenous silty gray shale that forms an excellent roof. Local high-sulfur cells, which seem to contradict the regional low-sulfur explanation for the Springfield Coal, can be attributed to thin pyritic shale lenses traceable back to the channel.

Geologic models are continually updated. Annual core drilling and mine mapping remain the best sources of data. A rigorous program of core description, geophysical logging, and mechanical rock testing has evolved. Numerous oil-well electric logs augment the modeling database. Core photography has proven essential to engineer-geologist communication.

AAPG Search and Discovery Article #91023©1989 AAPG Eastern Section, Sept. 10-13, 1989, Bloomington, Indiana.