ORIGINS OF MOAB VALLEY DOLOMITES: IMPLICATIONS FOR ENERGY RESOURCE EXPLORATION AND STORAGE

The well-exposed diapir-proximate dolomites of the Moab Valley, Utah provide an outstanding opportunity to gain insights into carbonate emplacement mechanisms within salt systems, fluid flow within diapir margins, and the extent of the heterogeneity of the Layered Evaporite Sequence of the Paradox Basin. These insights have significant implications for energy resource exploration and energy transition endeavors, such as CO₂ sequestration, H₂ storage, and nuclear waste storage.

At Moab Valley, these dolomites differ from one side of the valley to the other. They are distinct in regard to their stratigraphic position relative to other lithologies, their content of detrital material and dead oil, and their fabrics. Given that carbonates typically reflect their environment and conditions of formation, this sharp contrast in lithological expression across the valley raises questions about earlier works suggesting a common origin. Consequently, this study investigated potential different origins, ranging from Pennsylvanian carbonate megaflap and Pennsylvanian inclusion of non-evaporite lithology to Triassic lake deposits, Triassic replacement carbonate caprock, modern karst and spring tufa.

The study integrates geologic fieldwork, petrography, stable O & C isotope geochemistry, stratigraphy, drone imagery, and new geologic mapping. Following extensive fieldwork, 121 samples were analyzed for petrography and 50 for isotope fingerprinting. The data reveal three dolostone categories: (1) interlayered with gypsum, common on both sides of the valley; (2) finely laminated dolostone with algal mats on the southwest side, interfingering with the Chinle Formation without gypsum; (3) circum-diapir dolostone, unique to the northeast side, lacking clear regional stratigraphic correlation across the Basin.

These findings offer critical insights into the varied origins of Moab Valley dolostones. Their characteristics and distribution have implications for energy resource exploration and storage. Understanding the variability in these dolostone formations and their distribution can influence selection of suitable sites for CO₂ sequestration, H₂ storage, and nuclear waste storage in the Paradox Basin. Moreover, the presence of dead oil can offer insights into the timing of hydrocarbon maturation and migration within this part of the Paradox Basin.