New Kinematic Model of the Early Opening of the Equatorial Atlantic Realm

Abstract The opening of the Equatorial Atlantic Ocean constitutes the final stage of Gondwana's breakup, leading to the separation of the African and South American continents. The early spreading has been debated due to the absence of magnetic anomalies related to the Early Cretaceous opening at low latitude, and an incomplete fracture zone record, hidden by volcanic overprint and/or partially subducted. This study proposes a novel kinematic reconstruction dedicated to the Equatorial Atlantic rifting refined from an existing model. Our approach integrates seismic and gravimetry data from the margin of the Equatorial Atlantic. We propose a new segmentation of the Equatorial Atlantic, with the St Paul Fracture Zone delineating the northern and southern Equatorial Atlantic domains. Based on the continental margin obliquity of the northern Equatorial Atlantic, and the Cretaceous Jurassic Line dividing the Equatorial Ocean from the Central Atlantic Oceans, we propose an early opening history of the northern Equatorial Atlantic in two phases. A primary Early Cretaceous phase involves strike‐slip movement between West Africa and the Guyana block. This rifting phase is accommodated by introducing intraplate deformation in the Amazon basins. In the Albian, a kinematic reorganization associated with the northward propagation of the South Atlantic leads to a secondary and final opening phase of the entire Equatorial Atlantic. This new model enhances the understanding of the regional tectonics and kinematics history, with potential implications on the Lesser Antilles Arc subduction geohazards, and on the evolution of the triple junction between the Equatorial Atlantic, Central Atlantic, and proto‐Caribbean oceans.