Almost all Paleozoic strata in the Michigan Basin display elevated levels of organic maturity that cannot be explained by present-day burial depths, geothermal gradients, and heat flow. Likewise, higher heat flow from the basement in the past is unsatisfactory as an explanation of the elevated maturities, particularly for the younger sediments. Previous studies have concluded that a significant amount of Permo-Carboniferous overburden has been removed from this region by early Mesozoic regional uplift and erosion. If the missing overburden were sufficiently thick and thermally resistive, a “thermal blanket” effect would have caused elevated temperatures throughout the underlying stratigraphic section during...