Tectonic, foreland-basin origins of Upper Ordovician black gas shales in the Appalachian Basin of eastern United States

Abstract

Black gas shales are major parts of many foreland-basin sequences and comprise important components of unconformity-bound tectophase cycles, which reflect sedimentary/stratigraphic, flexural responses to deformational loading and relaxation in an orogen. Using as examples Upper Ordovician black gas shales, deposited during the Taconian orogeny in the Appalachian Basin of the eastern United States, black-shale origins and their importance in understanding the tectonic framework are discussed. Foreland-basin black shales are clearly the product of distinctive tectonic frameworks and histories, and aside from economic value, may provide important controls on the timing and location of tectonic events.

Keywords

• black gas shales
• tectophase cycles
• taconian orogeny
• upper ordovician
• appalachian basin
• tectonic framework