SEDIMENTOLOGIC AND PETROLOGIC CHARACTERIZATION OF A MAJOR GEOLOGIC CARBON SINK: THE PALUXY FORMATION, CITRONELLE DOME, GULF OF MEXICO BASIN, ALABAMA

This study is aimed at understanding the potential of Lower Cretaceous redbeds to store commercial quantities of anthropogenic CO₂ in the Gulf Coast. Citronelle Dome is a simple salt-cored anticline in south Alabama that hosts the ongoing SECARB Anthropogenic Test, in which CO₂ from a coal-fired power plant is being captured, transported, and injected into a saline formation. The dome is a salt-cored anticline that lacks faults, contains multiple reservoir sandstone units and a range of mudstone, evaporite, and carbonate seals. The Paluxy Formation was deposited in continental, environments that included bedload-dominated fluvial systems and interfluvial paleosols. The Paluxy is a coarsening-upward succession composed of numerous stacked, aggradational sandstone-mudstone packages. Individual sandstone bodies have sharp bases, typically fine upward, and range in thickness from less than 10 feet to over 40 feet.

Petrographic analysis of indicates that the sandstone units are composed of arkose to quartzarenite. Porosity and permeability are well-developed in the sandstone, with values commonly exceeding 20% and 200 mD, respectively; permeability locally exceeds 3800 mD. Intergranular pores predominate, and intragranular pores are common in feldspar. Secondary porosity is attributed mainly to dissolution of feldspar. Quartz is the most abundant authigenic cement and is expressed primarily as overgrowths; pore-filling calcite and ferroan dolomite also are common. Authigenic clay includes grain-coating illite and pore-filling kaolinite. Provenance analysis indicates that most of the detritus originated in transitional continental to craton interior settings. Most diagenesis occurred during pedogenesis, and ferroan dolomite preciptated during later burial. Many Cretaceous sandstone units in the eastern Gulf Coast resemble the Paluxy Formation at Citronelle, indicating exceptional storage capacity exists in the Cretaceous redbeds of the region.