Middle Ordovician of the Michigan Basin

The Michigan Basin in its present form began during the late Middle Ordovician time. During Glenwood time, the basin area experienced the initial transgression of the Middle Ordovician sea over the pre-Middle Ordovician unconformity surface. Basinal subsidence created an embayment of the Middle Ordovician sea in the area during Black River time. Increased subsidence created a closed basin centering in southern Lake Huron during Trenton time.;Basement block movement took place during Trenton time in the northern Lower Peninsula, creating wrench faulting in the overlying sediments. Due to the similarity of this structure to the structure in the Albion-Scipio trend of petroleum production, it is viewed as a prime area for future petroleum exploration. With this structural model in mind, several other possibly similar structures are suggested.