Distribution of Naturally Occurring CO2 in Shallow Marine Sediments in the US deep-water Gulf of Mexico

The Gulf of Mexico is a widely studied and well-known carbon sink, but regional examination of seepage comprises a critical data gap. CO₂ concentrations from over 1,000 piston cores are displayed to illustrate levels of naturally-occurring CO₂ in shallow marine sediments throughout the US deep-water Gulf of Mexico. Measured CO₂ concentrations display a wide range of values, from less than 500 to over 150,000 ppmV, and vary spatially with isolated anomalies dispersed throughout, but a cluster of elevated concentrations in the abyssal plain are observed. Given the recent rise in interest for carbon capture and storage (CCS) programs in the Gulf of Mexico, it is essential to understand the natural occurrence of CO₂ in marine sediments, which will enable us to better constrain pre-existing natural leakage, identify sites that may serve as natural laboratories for further investigation, and guide efforts into potential CCS site selection.