Abstract

The northern Paradox Basin is characterized by a variety of salt-related structures ranging from deeply buried salt pillows to faulted diapirs and salt walls exposed at the surface that evolved as a result of basement uplift, loading, creation of accommodation space, differential sedimentation, and salt movement.

Seismic, well, and published data define the proximal Cutler Group (Permian) as a basinward prograding unit that caused underlying salt within the Paradox Formation (Pennsylvanian) to flow in the same direction, i.e. towards the southwest. The highest rates of sediment accumulation, salt wall growth, salt evacuation (in the welded areas), salt area decrease, and subsidence occurred during Cutler time, when uplift and erosion of the Uncompahgre massif was most active. Sequential structural restorations indicate that the more proximal salt structures (e.g. the Onion Creek salt wall) evolved earlier than the more distal ones (e.g. the Moab salt wall). The degree of salt withdrawal was dependent on the amount of mobile salt available within the Paradox Formation, which varied with complex facies development across the basin. Areas that contained little or no original mobile salt persisted as platforms within the basin, significantly influencing subsequent progradation within the Cutler Group sequences. A revised model for the deposition of the Pennsylvanian and Permian sequences in the northern Paradox Basin shows a complex evolution of minibasin depocenters through time and space, intimately related to the growing salt structures in the basin.

This new understanding of the salt system evolution in the northern Paradox Basin impacts future petroleum exploration targets by defining a series of play concepts within the Paradox Formation, Honaker Trail Formation, and Cutler Group (particularly the White Rim Sandstone).