Mapping a proximal breakaway complex: Evidence of inherited basement fabric reactivation and polyphase rifting leading to the opening of a V-shaped basin at the Campos rifted margin proximal domain

While proximal domains in rifted margins are commonly associated with moderate crustal thinning, those developed along ancient orogenic belts, for example,can show more complex architectures influenced by pre-existing heterogeneities. Here, the interplay between inherited and rift-related structures is crucial, contributing to the complexity of these proximal marginal domains. This study investigates the role of pre-existing Gondwana structures in the development of a proximal breakaway complex, and the formation of a V-shaped basin within the Cretaceous Campos Basin. We use seismic reflection data and potential-field maps to characterize the structural framework of the study area. By combining observations regarding basement morphology, fault systems, and intracrustal reflectors, with gravity and magnetic sources, the study proposes a three-segment structural model (north, central, south) for the central Campos proximal domain. Wediscuss the reactivation of pre-existing basement fabric that led to the exhumation ofa middle ductile crust coeval to a localized shift of depocenters in the Barremian. These processes influenced the spatial distribution of faults and the development of a secondary WNW-ESE transfer zone, as well as the opening of a V-shaped basin associated with adome-shaped Central High. This study delineates a boundary for the Campos proximal domain and discusses, for the first time in the Campos Basin, the opening of a V-shaped basin as a result of differing vertical mechanical behavior combined with a sequence of tectonic reactivations of pre-existing basement structures. This contribution aims at enhancing our understanding of structural responses of a heterogeneous crust during the initial stages of rifting. • We characterized a proximal breakaway complex at the central Campos rifted margin. • ⁠Pre-existing basement fabric reactivation drove middle crust exhumation. • ⁠Rift structures include a minor E-W transfer zone and detachment faults. • Tectonic reactivations led to shifting depocenters and opening of a V-shaped basin.