Abstract: A New Interpretation of the Subsidence History of the Michigan Basin Based on Thermal Modeling
EVERHAM, WILLIAM D., and JACQUELINE E. HUNTOON, Michigan Technological University.
The large-scale thermal history of the Michigan Basin was investigated as part of a DOE-funded project to increase recovery from the Devonian Dundee Formation. Previous studies of the Michigan Basin's thermal history have suffered from an inability to generate models that match observed data from the entire stratigraphic section.
The results of this study suggest that models assuming high heat flow during the basin's early history, and using burial histories that incorporate deposition and subsequent erosion of sediment at stratigraphic levels now represented by unconformities can accurately predict observed levels of thermal maturity for the entire stratigraphic section. Modeling was performed using a finite difference solution to the one-dimensional heat conduction equation. The model allows the user to specify the surface temperature and basal heat flow boundary conditions, as well as the timing, duration and magnitude of deposition and erosion events, and the thermal conductivities of sediments and basement rocks. Original depositional thicknesses of sedimentary units are calculated by decompacting units from their present-day thicknesses.
Wells containing publicly available vitrinite reflectance data were modeled in this study. Models incorporated a time-dependent heat flow history that produced the best-fit to observed data when an elevated heat flow (120 mW/m2) was assumed from the start of the model at 510 Ma until the Late Silurian (407 Ma). Heat flow in the models reached an equilibrium value of 56 mW/m2 at 403 Ma. Results of the modeling indicate that burial histories incorporating deposition and subsequent erosion of approximately 2.0-2.5 km of material at the Silurian/Devonian boundary, and on the order of 2.0 km of Late Carboniferous/Permian material produce models which match observed data from throughout the basin.
AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah