Aptian flood basalts in Bacalhau oil and gas field: petrogenesis and geodynamics of post-rift tholeiites in the pre-salt sequence of Santos Basin, Brazil

Ecosystem transformation upon Aptian seawater ingress into the Proto-South Atlantic Ocean

“…The initial interval, previously identi ed in several studies 40,47,48 , is attributed to distinctly continental sources, serving as a signi cant geochemical indicator supporting the interpretation of the carbonate succession as having a lacustrine origin in the Campos and Santos basins. Despite the limited understanding of the paleo-tectonic context, the notable variability in the strontium isotope signal indicates a depositional system in uenced by a range of sources, including continental cratonic rocks and contemporaneous basaltic volcanism as potential contributors 37,49 . The second interval, however, exhibits notably reduced radiogenic Sr values, predominantly around 0.709, indicating a distinct decrease in radiogenic sources entering the basin.…”

“…However, there is a lack of unequivocal marine evidence in the SE Brazilian marginal basins (e.g., Campos and Santos Basins). Accordingly, a series of southward marine transgressions from the equatorial Tethys Ocean was hypothesized 7,8 divergent from the tectonic evidence of a marine pathway extending from south to north on the basis of sea-oor spreading patterns and geodynamic reconstructions 16,17,18,19 , recently acquired geochronological data 37,49 and from evidence gathered from the conjugate margins of West Africa 9 .…”