Abstract We investigate the evolution of the Iberia–Newfoundland margin from Permian post-orogenic extension to Early Cretaceous break-up. We used a Quantitative Basin Analysis approach to integrate seismic stratigraphic interpretations and drill-hole data of two representative sections across the Iberia–Newfoundland margin with kinematic models for lithospheric thinning and subsequent flexural readjustment. We model the distribution of extension and thinning, palaeobathymetry, crustal structure, and subsidence and uplift history as functions of space and time. We start our modelling following post-orogenic extension, magmatic underplating and thermal re-equilibration of the Permian lithosphere. During the Late Triassic–Early Jurassic, broadly distributed, depth-independent lithospheric extension evolved into Late Jurassic–Early Cretaceous depth-dependent thinning as crustal extension progressed from distributed to focused deformation. During this time, palaeobathymetries rapidly deepened across the margin. Modelling of the southern and northern profiles highlighted the rapid development of crustal deformation from south to north over a 5–10 myr period, which accounts for the rapid change in Tithonian–Valanginian, deep- to shallow-water sedimentary facies between the Abyssal Plain and the adjacent Galicia Bank, respectively. Late-stage deformation of both margins was characterized by brittle deformation of the remaining continental crust, which led to exhumation of subcontinental mantle and, eventually, continental break-up and seafloor spreading.

The Puna Plateau, a high-elevation portion of the central Andean Plateau, possesses some of the thickest crust on Earth, and its structural growth should be reflected in the adjacent foreland basin (present-day Eastern Cordillera and Santa Bárbara system) as a flexural response to crustal thickening via contractional deformation. The Cretaceous–Cenozoic stratigraphy preserved within the Eastern Cordillera and Santa Bárbara system also records the influence of the Cretaceous Salta Rift system, which heavily influenced depositional patterns in the region, particularly during postrift thermal subsidence. The Eastern Cordillera and Santa Bárbara system were significantly modified by Neogene inversion of Salta Rift basins, which subdivide the foreland basin and localize depocenters. Here, we examine results of two-dimensional kinematic models of basin formation and fill that proxy the thermal and mechanical behavior of the Salta rifting, and superimpose upon this rifting event two different scenarios for the temporal growth of the Puna Plateau—one with crustal thickening predominantly in the Eocene, and another with progressive crustal thickening beginning in the early Miocene. The two models attempt to forecast the combined effects of inherited rift history and growth of the Puna Plateau on the development of accommodation within the adjacent foreland basin. A Neogene (Miocene-age) Puna Plateau scenario creates a coeval foredeep within the Salta Rift system, but its magnitude and wavelength are influenced by crustal thickening in the Eastern Cordillera and Santa Bárbara system. In contrast, a Paleogene (Eocene-age) growth scenario for the Puna Plateau results in a substantial amount of coeval flexural accommodation in the adjacent Eastern Cordillera that extends across most of the Salta Rift system, which is broken up by subsequent loading in the Eastern Cordillera and Santa Bárbara system. Thermal subsidence associated with thinned or delaminated mantle lithosphere in the Late Cretaceous also contributes to accommodation and is most prominent during periods of tectonic quiescence. Our modeling results show that: (1) Neogene topographic growth of the Puna Plateau produces a basin subsidence history that is consistent with the geologic record, (2) the Salta Rift system was not buried deeply prior to Neogene exhumation, (3) the eastward advance of the flexural foreland can be related to crustal thickening and elevation gain of the Puna Plateau and Eastern Cordillera at ca. 15 Ma, and (4) interpretations of foreland subsidence history across the Eastern Cordillera may need to consider the influence of thinned mantle lithosphere during Late Cretaceous Salta rifting, which continues to create some accommodation in the region through subtle thermal subsidence.

Abstract Satellite-derived gravity anomalies were used to map the location and distribution of rift subbasins comprising the Campos and Santos Basins of the southeastern Brazilian continental margin. Free-air and crustal Bouguer gravity anomalies define several features. A negative–positive gravity gradient along the southeastern Brazilian margin correlates generally with termination of oceanic fracture zones, the boundary of synrift evaporites, and an abrupt change in anomaly trends from east-west to margin-parallel. The gravity gradient thus defines the location of the ocean–continent boundary and suggests that much of the São Paulo Plateau is underlain by thinned continental crust. Second, a major offshore tectonic hinge zone, consisting of a series of short-segment, en echelon, high-standing blocks subparallel to the Brazilian margin demarcates the western limit of significant continental extension. The Badejo High of the Campos Basin is part of this hinge zone trend. The Serra do Mar and Serra da Mantiqueira mountains represent an onshore hinge zone. Third, a series of major rift subbasins exist seaward of both the Campos and Santos hinge zones. These have limited along-strike continuity, implying that synrift lake communication, water chemistry, and possibly source quality and preservation were restricted to each subbasin. Extension between west Africa and Brazil occurred during the Early Cretaceous as a series of rift pulses that culminated in the initiation of sea floor spreading. The Congo–Cabinda margin of west Africa and the Camamu–Almada margin of eastern Brazil are characterized by a common tripartite rift history: Berriasian–Hauterivian, Hauterivian–middle Barremian, and late Barremian–early Aptian. Early depth-independent, broadly distributed, and increasingly focused brittle deformation (rift phases I and II) was replaced by depth-dependent deformation dominated by plastic thinning of the lower crust and lithospheric mantle (rift phase III). The nonmarine part of the Lagoa Feia Formation correlates with rift phase II while the “transitional” part is associated with rift phase III. The intervening pre-Alagoas unconformity is equivalent to the pre-Chela unconformity on the Congo margin. The possibility of a mid-crustal detachment beneath the Brazilian margin active during rift phase III has profound implications for the hydrocarbon maturation history of the margin. Seismic reflection data from the São João da Barra Low (Campos Basin) have helped define an early synrift depositional package that likely equates with rift phase I.