An understanding of regional orogenic, climatic, and eustatic processes is critical to interbasinal correlation of Paleozoic strata in eastern North America. Tectonic activity associated with the culmination of Appalachian orogenic events has been shown to have regional influence on paleostructure and sediment dispersal in the Appalachian foreland basin and adjacent intracratonic Illinois and Michigan Basins. The culmination of the Acadian orogeny at the end of the Devonian represents the beginning of a period of general tectonic quiescence extending throughout the early and middle Mississippian in eastern North America. Early Mississippian strata in the Michigan Basin are distinctive and mark the transition from marine shale and carbonate-dominated sedimentation during much of the Late Ordovician through Late Devonian to siliciclastic-dominated deposition throughout much of the Carboniferous. The Osagean Stage Marshall Formation constitutes an important coarse-grained siliciclastic formation in the Michigan Basin. Despite numerous outcrop studies and early subsurface investigations, the Marshall Formation remains poorly understood in terms of depositional controls and stratigraphic relationships to related Mississippian strata in Michigan and correlative strata in adjacent basins.

This work documents sedimentological and sequence stratigraphic relationships in early–middle Mississippian, generally clastic-dominated strata of the Marshall and lower Michigan Formations (as described in previous literature). Utilizing 535 well logs and core-to-log calibration in conjunction with detailed descriptions of seven cored intervals spanning the Michigan Basin, new stratigraphic relationships are presented suggesting the Marshall Formation and informal stray sandstone units are genetically related and reflect tectonic, eustatic, and climatic processes that occurred in the Michigan Basin during the early Carboniferous.