oa Comparative Geochemical Analysis between the ParÁ-Maranhão Basin (Brazilian Equatorial Margin) and Tano Basin (Ghana)

The Pará-Maranhão Basin, located on the Brazilian Equatorial Margin, remains underexplored despite its potential as an analog to the hydrocarbon-rich Tano Basin (Ghana) on the African Equatorial Margin. This study evaluates the basin’s source rock potential through geochemical analyses (Rock-Eval pyrolysis, TOC, vitrinite reflectance) of three intervals: Aptian (Codó Formation), Albian (Caju Group), and Turonian-Santonian (Travosas Formation).

The Aptian shows moderate hydrocarbon generation potential with TOC up to 3.43 wt% (though most samples <1.20 wt%) and Type II kerogen, displaying the highest thermal maturity (Ro: 0.74-0.86%; Tmax: 440-464°C). The Albian emerges as the most promising interval, with high TOC (up to 2.73 wt%), Type II-III kerogen, and optimal maturity within the oil window (Ro: 0.7%; Tmax: 437-455°C). In contrast, the Turonian-Santonian exhibits lower hydrocarbon generation potential (TOC =3 wt%, HI <2.5 mg HC/g rock) with maturity (Ro: 0.5-0.6%) and mixed Type II-III kerogen.

Comparative analysis with the Tano Basin reveals similar kerogen types (mixed marine-terrestrial) but greater thermal maturity in Pará-Maranhão. All intervals show increasing TOC with depth (∼3,500 m), suggesting enhanced potential in deeper sections. Although limited to shelf data, this study highlights the basin’s hydrocarbon prospects, particularly in unexplored deep-water areas, mirroring trends observed in its African counterpart.