DRIVERS OF SUBSIDENCE AND SEDIMENTATION IN THE PARADOX BASIN DURING THE LATE PALEOZOIC

The Paradox Basin is a key feature of the enigmatic swath of late Paleozoic North American intraplate tectonic deformation termed the Ancestral Rocky Mountains (ARM). We evaluate several fundamental questions in the Paradox Basin using the record of subsidence and sediment routing to understand the geodynamic mechanisms that drove ARM tectonics. Outstanding questions include: 1) What were the subsidence patterns and mechanisms throughout the basin in the late Paleozoic? 2) How did mobile salt bodies affect accommodation? 3) What does the distribution of basement-derived sediment in the basin tell us about exhumation of the adjacent Uncompahgre Uplift (UU) and associated sediment routing to Paradox Basin depocenter(s)? We address these questions using new and published detrital zircon data, sediment source maps, and 1D and 2D subsidence models. Previous work in the Paradox Basin has demonstrated that flexure, driven by the bounding UU to the east, was the primary driver of subsidence. We extend this analysis along strike, creating pseudo-3D flexural subsidence maps using multiple parallel subsidence profiles. We show that flexure alone cannot account for accommodation patterns through time, and a full accounting of subsidence requires inclusion of salt movement in the deeper part of the basin, proximal to the UU. Paleocurrent and sediment provenance data indicate that the UU was the primary sediment source. However, the range of Cambrian to Paleoproterozoic crystallization ages exposed in the UU, revealed through bottom-up sediment source modeling, allows us to map late Paleozoic sediment routing systems in the basin. Sediment source maps created with these data illustrate the distribution of basement ages exposed along the UU, sediment routing pathways, and downstream mixing of detrital zircon age populations. Further, these maps show that there was little or no connectivity between siliciclastic sediment systems in the Paradox Basin to the north and the adjacent San Juan Trough to the south although they have previously been considered a unified depocenter. This study reconstructs development of both the Paradox Basin and the UU, and in turn provides insight into the spatial and temporal evolution of ARM tectonics