Modern Fluid Indicators of Sources and Migration of Paleofluids in the Colorado Plateau

Jihyun Kim1, Ambria Dell'Oro1, Chandler Noyes1, Jennifer McIntosh1, Rebecca Tyne2, Chris Ballentine2, and Zheng-Tian Lu3

1Department of Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ

2University of Oxford, Oxford, England, UK

3University of Science and Technology of China, Hefei, China

The Paradox Basin, located in SE Utah and SW Colorado, contains iconic regional sandstone bleaching, evidence of basinal-scale hydrocarbon and metal migration, and extensive evaporite deposits. Brines associated with the Paradox Formation (salt) are mostly connate waters derived from evaporated paleoseawater. There is also evidence of brines formed by salt dissolution associated with meteoric recharge. As part of a large, interdisciplinary project recently funded by the Keck Foundation, we aim to identify the sources, residence time, and migration mechanisms of modern (remnant) fluids in the Paradox Basin to better understand the paleofluid flow history of the Colorado Plateau. Our study will focus on characterizing the chemical and isotopic composition of formation waters and associated hydrocarbons, noble gases, and carbon dioxide. Krypton isotopes (81Kr) will be used for the first time to ‘date’ near-surface saline fluids and better constrain crustal 4He fluxes and ‘ages’ of deeper fluids. Various sample locations and depths will be considered to characterize the spatial and depth distribution of modern fluids. Results will be used to validate a basin-scale hydrodynamic model and coupled to evidence of paleofluid flow in the rock record.