Date of Award


Degree Name

Master of Science




Diane I. Doser


The Onion Creek salt diapir lies within the Paradox Basin of Utah where it forms part of a series of salt walls that separate the Paradox Basin into smaller sub-basins. These sub-basins and associated salt diapirs remain key to several oil and gas traps in the region. A series of anomalous tight folds occur on the northern side of the Onion Creek diapir within the Permian Cutler Group Undifferentiated. These folds are thought to be associated with a shallow detachment horizon with three possible origins:1) a weak shale layer within the Cutler Group, 2) a salt shoulder, or 3) a salt namakier. I use gravity and magnetics methods to better determine the extent and geometry of the Onion Creek salt body in order to constrain the origin of the detachment horizon. Since the salt is less dense than the Cutler Group siliciclastics, gravity methods are some of the best at defining the extent of salt in the subsurface, while magnetic methods help delineate the more highly magnetic Cutler siliciclastics. Gravity data collected shows a low gravity anomaly over the diapir and then a gradual increase in gravity readings as more of the Cutler Group covers the subsurface salt. Magnetic data display a similar trend with a low over the diapir with values that generally increase with more Cutler sediment cover. By modeling these data in 2D with a newly developed software, a best-fit model can be chosen for the concealed salt structure on the northern margin at Onion Creek. This modeling process indicated a salt shoulder model best fit the geophysical data. These results suggest gravity and magnetic methods are a low-cost alternative to seismic surveys to evaluate what subsurface salt structure can be present for oil and gas exploration studies. Knowing these salt geometries are key to developing a safe, effective, and high-recovery drilling plan.




Received from ProQuest

File Size

99 pages

File Format


Rights Holder

Julia Michelle Astromovich