Early opening of the Central Atlantic and its connection to the Western Tethys

                Deciphering the dynamics of continental breakup is fundamental to understanding how oceanic basins initiate, segment, propagate and connect to the global oceanic system. However, constraining the spatial and temporal evolution of continental rupture is challenging as it precedes the establishment of continuous oceanic spreading and reliable kinematic markers such as marine magnetic anomalies. Here we focus on the earliest stage of Pangea breakup, with the aim of constraining basin segmentation during the initial opening of the Central Atlantic Ocean (CAO), prior to its connection with the main Panthalassa Ocean through the Western Tethys.

                The CAO corresponds to the earliest opened branch of the Atlantic.  The timing of its continental breakup and onset of oceanic spreading remains debated, with proposed breakup ages ranging from 195 Ma to 175 Ma. This uncertainty leads to major ambiguities in the geodynamic context of continental rupture, with consequences for the interpretation of rifted and nascent oceanic basins segmentation, connectivity, and associated depositional environments. It also affects the interpretation of major Jurassic magnetic anomalies identified across the CAO: the East Coast Magnetic Anomaly (ECMA) and Blake Spur Magnetic Anomaly (BSMA), which are commonly used as kinematic markers in early Atlantic reconstruction.

                To address these issues, we have compiled a regional database to integrate major rift structures and basins, Upper Triassic salt distribution, and variations in the nature of the ocean-continent-transition and magmatic type. We present interpretations of seismic reflection data along the Central Atlantic rifted margins, calibrated using available drilling results. These data allow us to constrain rift basin age and architecture, fault system development and the distribution of rift-related salt provinces. In parallel, regional crustal thickness maps derived from gravity inversion are used to investigate along-strike variations in magmatic budget during continental breakup and the early stages of oceanic accretion, relation with the spatial distribution of the ECMA and BSMA.

                Our first results confirm pronounced along-strike variations in magmatic volumes emplaced during continental breakup and the initial phases of oceanic spreading. The newly compiled database will provide key constraints for paleogeographic reconstructions, with the aim of clarifying the duration of oceanic basin isolation, the timing of basin connectivity through the Western Tethys and sedimentation pathways associated with the early Atlantic evolution.