GEOLOGIC CONTROLS ON MID-CONTINENT RESOURCES FOR THE ENERGY TRANSITION, THE OKLAHOMA PERSPECTIVE

The mid-continent is enriched in critical minerals and elements, as well as valuable non-hydrocarbon resources that do not fall into supply-chain-restricted categories. The geologic controls on these resources fall into three broad categories: (i) the spatiotemporal distribution of the Proterozoic mid-continent rift, (ii) the stratigraphic and geochemical evolution of the mid-Paleozoic intracontinental seaway, and (iii) diagenetic processes, occurring from the Mesozoic to Recent time. For (i), the Wichita Mountains provide rare outcrops of basement rocks, such as granitic units that host hydrothermal veins rich in PGEs, REEs, as well as other metals. The structural geology and geophysics of the region point to a more widespread system, including well-documented gravity and magnetic anomalies of the mid-continent rift. Regionally, surface exposures are limited due to several thrusts that cut off mafic units that may have their own distinctive magmatic-hydrothermal mineral systems. Detailed field mapping of the area’s surface and/or near-surface exposures will result in a more coherent resource model. For (ii) mid-Paleozoic (Mississippian-Permian) seaways lead to the extensive shale and carbonate deposits. Coal and associated underclays, including Phosphate nodules that are potentially rich in REEs. To the west, the edges of the extensive Permian salt deposits may host important resources such as Li. The evolution of organic-rich materials and evaporitic sections depended on the evolution of the intracontinental seaway through the late Paleozoic. Lastly, (iii) knowledge about elemental enrichment in the Oklahoma subsurface stems from concentrations of produced water. These data are semiquantitative given their derivation from large-scale, regional hydrocarbon production, but anomalies in He, Li, and other elements are common, especially in the north-central areas of the state. Elsewhere in the state, anomalies in Iodine – OK is the only domestic producer of commercial I – as well as Ba (OK “Rose Rocks”) point to the manner in which diagenetic fluid flow superposes depositional controls, resulting in elemental and mineral enrichment. A regional resource model will require an understanding of the tectonomagmatic, depositional, and fluid-flow history over geologic time.