Structural and Stratigraphic History of a Deformed Diapir Margin, Onion Creek Salt Diapir, Paradox Basin, Utah
The Onion Creek Salt Diapir (OCSD) located in the northern Paradox Basin in Utah is a 0.6 km wide × 3.6 km long × 1.6 km tall salt diapir surrounded by variably deformed Paleozoic through Cenozoic strata. The area is a classic area for the study of deformation around salt diapirs. This study uses high-resolution GPS-enabled-tablet and 3D photogrammetric outcrop model-based field mapping, section measuring, thin section petrography, structural restorations, and newly developed 3D modelling workflows to document the styles, timing, nature, and distribution of deformation in strata surrounding the OCSD. Permian Cutler Group sediments on the northern margin of the diapir are differentiated into 14 informal units which document fluvial system interactions with an abruptly narrowing diapir. Burial wedges deposited above a 600m wide instep of the diapir margin are composed of 8 wedge halokinetic sequences within 4 tapered composite halokinetic sequences that thin, but do not change facies across an instep of the diapir margin and are syndepositionally folded. Eight radial-fault bounded structural domains are recognized, each containing syndepositional folds. Folds vary in style and wavelength both stratigraphically, and laterally across the diapir margin. Synclines form microbasins adjacent to the diapir that increase in wavelength in younger strata. Radial faults offset fold axes and allow structural domains to move variably against each other. Isopach, facies, and paleocurrent data show that fluvial systems progressively onlap and erode into the top of the diapir through the entire Permian Cutler stratigraphy, suggesting that the OCSD did not serve as a topographic barrier to fluvial systems. This study uses a newly developed workflow to apply thin section derived rock composition data to a 3D model for the purpose of investigating potential relationships between porosity, cement and fault distributions. Thin section petrology point counts and 3D interpolation of porosity data across faults suggests that near-diapir faults may have served as conduits for near-diapir fluid systems. On the SW margin of the diapir Permian Cutler Group strata are fault truncated against isolated slivers of Paradox salt that form a salt horn structure, not a salt glacier as previously thought. Mesozoic strata thin towards the diapir, showing that passive diapirism continued into the Jurassic. Variations in collapse block geometry from the SW margin of the OCSD to the SE margin of the OCSD suggest that the underlaying megaflap morphology may have served as a partial control on collapse block geometry and distribution. This work provides an example of how salt tectonics influences accommodation space near a salt diapir and is applicable in the mineral, resource storage, carbon capture and energy industries. This work also introduces a unique workflow for the visualization of field-derived attribute data onto 3D outcrop models for the purpose of data interpolation and visualization.
Lankford-Bravo, David Felipe, "Structural and Stratigraphic History of a Deformed Diapir Margin, Onion Creek Salt Diapir, Paradox Basin, Utah" (2021). ETD Collection for University of Texas, El Paso. AAI28865438.