The Early-Middle Mississippian Borden-Grainger-Fort Payne delta/basin complex: Field evidence for delta sedimentation, basin starvation, mud-mound genesis, and tectonism during the Neoacadian Orogeny

In latest Devonian time, the collision between Avalonia, the New York promontory and Carolina terrane under the impact of Gondwana, generated an orogeny that began in New England and migrated southward in time. Once thought to be the fourth tectophase of the Acadian orogeny, this event is now called the Neoacadian orogeny. Active deformational loading during the event initially produced the Sunbury blackshale basin, whereas subsequent relaxational phases produced the Borden-Grainger- Price-Pocono and Pennington-Mauch Chunk clastic wedges, which largely refl ect the dextral transpressional docking of the Carolina terrane against the Virginia promontory and points southward. The Sunbury black-shale basin and the infilling clastic wedges are among the thickest and most extensive in the Appalachian foreland basin. This trip will demonstrate differences in basinal black-shale and deltaic infilling of the foreland basin, both in more active, proximal and in more distal, sediment-starved parts of the basin. In particular, we will examine relationships between sedimentation and tectonism in the Early-Middle Mississippian Sunbury/Borden/Grainger/ Fort Payne delta/basin system in the western Appalachian Basin during the Neoacadian Orogeny. We will emphasize the interrelated aspects of delta sedimentation, basin starvation, and mud-mound genesis on and near the ancient Borden- Grainger delta front. Temporal constraints are provided by the underlying Devonian- Mississippian black shales and by the widespread Floyds Knob Bed/zone, a dated glauconite/ phosphorite interval that occurs across the distal delta/basin complex.