Paleoenvironment of the New Albany Shale Group ( Devonian- Mississippian) of Illinois.

The distribution of lithofacies was determined by wave energy, bottom oxygenation, and bottom topography in a deep water stratified anoxic basin. At the basin margin high energy, very shallow conditions are recorded by oolitic-skeletal grainstones and packstones with abundant brachiopods, crinoids and trilobites. Offshore, less agitated areas are represented by highly bioturbated carbonate wackestones, argillaceous quartz siltstones, and greenish-gray mudstones. Calcified invertebrates are generally rare, indicating dysaerobic conditions. Basinward, slope areas are characterized by olive-gray to black, weakly bioturbated shales commonly interbedded with thickly laminated black shales. Trace fossils are abundant. Anaerobic conditions prevailed in the deepest areas where finely laminated, undisturbed, pelagic black shales were deposited.- from Author