Early history of the Michigan Basin; subsidence and Appalachian tectonics

Geometries of Cambrian to Silurian stratigraphc sequences in the Michigan basin record discrete episodes of basin-centered subsidence separated by periods of regional tilting. Backstripping reveals irregular subsidence rates that argue against a simple thermal contraction model. Depositional facies architecture also reflects episodic subsidence patterns, basin-centered facies tracts dominating during subsidence reactivations. These three lines of evidence indicate that subsidence cessations and reactivations characterize the early history of the Michigan basin. Periods of episodic subsidence correlate temporally with orogenic events in the Appalachians, suggesting that reactivation of basin subsidence is related to tectonic activity. We propose that Appalachian orogenic activity caused the episodic subsidence of the Michigan basin, possibly through weakening of the lower crust and reactivation of a preexisting upper-crustal isostatic imbalance.