Late Triassic to Early Jurassic Sedimentological and Geochemical Evolution of the Syn-Rift Series of Berrechid Sub-Basin

Summary The Berrechid sub-basin, situated along the Central Atlantic Margin (CAM), represents a significant extensional basin formed during the late Triassic to early Jurassic break-up of Pangea. This study focuses on reconstructing the evolution of its syn-rift series, characterized by red beds and evaporites, and situating these findings within the broader context of Atlantic rift basins and the CAM. By using an integrated approach combining sedimentological and geochemical analyses, this research identifies two primary depositional environments and six sub-environments, interrupted by the Central Atlantic Magmatic Province (CAMP) basalt flows. These environments include proximal to distal alluvial-fan siliciclastic deposits and a shallow ephemeral hypersaline lake-salt pan-mudflat complex, reflecting a restricted continental setting from the Carnian? to the Hettangian-Sinemurian?. The study defines three evolutionary stages: early syn-rift, rift climax, and late syn-rift. Geochemical analyses of halite and red beds provide insights into paleoenvironmental conditions, including paleoredox, paleosalinity, paleoclimate, and terrigenous inputs. Isotopic 87Sr/86Sr data suggest non-marine sources for evaporite parent-waters, contrasting with Triassic-Jurassic seawater signatures. Comparisons with contemporaneous CAM basins reveal shared half-graben geometries but different depositional patterns, attributed to regional tectonic variations and climatic shifts due to the northward drift of the Pangea.