Assessing the Geologic Setting of the Circum-Diapir Carbonates of the Moab Valley, Southeastern Utah–Paradox Basin

The salt walls and adjacent strata of the Paradox Basin are important repositories for natural resources such as petroleum, potash, and uranium and hold considerable potential for H2 and CO2 storage. Despite their importance, the geologic origin and history of salt diapirism, sediment deposition in adjacent minibasins, and fluid flow are only recently being re-assessed in the context of a modern salt tectonic framework. This work re-evaluates the origin and geologic setting of carbonate units exposed around the Moab Valley salt wall within the Paradox Basin of southeastern Utah, where those on the southwest vs. the northeast side are distinctly different. The southwestern carbonates are meter-thick dolomite beds locally interbedded with dark gray carbonate mudstones typical of outcrops of the Paradox Formation. In contrast, the northeast side displays attributes not typical of the Paradox Formation, such as isolated pods of microcrystalline, non-fossiliferous dolomite either surrounded by gypsic diapiric caprock or concordant with Triassic Chinle Formation strata. These carbonates were previously mapped and grouped together as part of the Hermosa Group. However, our new mapping shows there are at least three distinct carbonate units in the area: one that appears to be lacustrine facies within the Chinle Formation, another belonging to the layered evaporite sequence of the Paradox Formation, and a third without any known stratigraphic correlation to any of the basin’s formations. Further analyses will involve petrography, carbon and oxygen isotopes, and 2D seismic to clarify the origin(s) of the carbonates.