A stratigraphic analysis of Paleozoic and Mesozoic strata in the northern Denver basin shows that recurrent movement on basement faults influenced sedimentation, especially during major sea-level changes. The research integrates surface and subsurface data for an area of approximately 30,000 mi2 (77,700 km2).
Twenty stratigraphic intervals in the Paleozoic and Mesozoic were identified from well data. Areas of thickness variations on isopach maps within these stratigraphic intervals are caused by onlap, offlap, convergence, and subtle unconformities which may be directly related to the development of paleostructure. In general, thin areas on isopach maps correspond to paleohighs and thick areas correspond to paleolows. In the northern Denver basin, four major northeast-trending paleostructures had recurrent movement during the Permian and Cretaceous, and three major northwest-trending paleostructures had recurrent movement during the Pennsylvanian, Permian, Triassic, and Cretaceous. Wedge-outs of Cambrian, Ordovician, Mississippian, and Triassic strata were also controlled by the northeast-and northwest-trending fault systems. In addition, the late Paleozoic stratigraphic sequence is thicker in the subsurface than in surface measured sections which is evidence for major paleostructure movement.
The tectonics and sedimentation model of recurrent fault-block movement will aid in the exploration for hydrocarbons in the Denver basin by predicting the distribution of both source and reservoir rocks and by identifying early traps associated with paleostructures. Moreover, the large number of wells which penetrate only the Cretaceous section may be used in some areas to predict the Paleozoic paleostructure.