Abstract: Utilization of Geophysics in Coal Exploration and Development

Wilfred P. Hasbrouck

Because coals exhibit marked differences in physical properties relative to those of the material that either surrounds or intrudes them, and because the geometry of many coal deposits is relatively simple, coal seams are excellent geophysical targets. The techniques of coal geophysics have a wide range of application--from delimiting coaliferous basins and exploring for coals within known provinces to planning and developing mines, locating long-abandoned coal mines, and determining subsidence effects associated with the old workings. Four cost-effective geophysical techniques are in almost everyday use: (1) high-resolution seismic reflection methods, employed in Great Britain to map tectonically disturbed zones and thus avoid areas in which longwall mining would be unec nomic; (2) seismic seam-wave techniques, used underground in Europe to certify bed continuity and to detect minor faulting within seams; (3) borehole geophysical methods, used widely as correlation tools and more recently as means to indicate coal quality; and (4) magnetic methods, used in the western United States to map burn (clinker) facies.

Other geophysical methods of demonstrated usefulness include the electrical-resistivity method, to map anthracite subcrops; the gravity method, to locate the edge of strippable-depth coal beds, to find glacial channels that can cut out coal seams, and to indicate thickness variations of shallow lignites; and the high-resolution seismic method, to map channel sandstones within and above coal beds and to map growth faults which not only can displace coal seams but also may control their deposition.

AAPG Search and Discovery Article #90969©1977 AAPG-SEPM Rocky Mountain Sections Meeting, Denver, Colorado