The Cenozoic East African Rift System (EARS) extends from the Red Sea to Mozambique. Here we use seismic reflection and bathymetric data to investigate the tectonic evolution of the offshore branch of the EARS. The data indicate multiple and time transgressive neotectonic deformations along~800 km of the continental margin of northern Mozambique. We observe a transition from a mature rift basin in the north to a juvenile fault zone in the south. The respective timing of deformation is derived from detailed seismic stratigraphy. In the north, a~30 km wide and more than 150 km long, N-S striking symmetric graben initiated as half-graben in the late Miocene. Extension accelerated in the Pliocene, causing a continuous conjugate border fault and symmetric rift graben. Coevally, the rift started to propagate southward, which resulted in a present-day~30 km wide half-graben, approximately 200 km farther south. Since the Pleistocene, the rift has continued to propagate another~300 km, where the incipient rift is reflected by subrecent small-scale normal faulting. Estimates of the overall brittle extension of the matured rift range between 5 and 12 km, with an along-strike southward decrease of the extension rate. The offshore portion of the EARS evolves magma poor, similar to the onshore western branch. The structural evolution of the offshore EARS is suggested to be related to and controlled by differing inherited lithospheric fabrics. Preexisting fabrics may not only guide and focus extension but also control rift architecture.

We present a new plate tectonic model for the breakup and dispersal of East and West Gondwana and subsequent formation of the Indian Ocean, focussed on the early evolution of the Eastern Margin of Africa. We start from a tight reconstruction of all the Precambrian pieces. Using primarily ocean-floor fracture zone data, the development of the ocean between India and Antarctica is resolved into four distinct spreading regimes and that between Antarctica and Africa into seven distinct regimes. The movement of Madagascar against Africa is then investigated as part of the plate–circuit closure between Africa and India in the Madagascar–Africa–Antarctica–India–Madagascar system. We conclude that a distinct change in plate tectonic regime off East Africa occurred at about 153 Ma (Kimmeridgian) when transforms were first activated offshore. Before this time, East and West Gondwana were separated by a rift, propagating from NE to SW and starting between 188 and 170 Ma. The model is defined by Euler interval poles, published here for the first time, and a refined global animation that may be inspected and copied from the URL www.reeves.nl/Gondwana. The analysis points to a small number of disruptive events in the otherwise inexorable growth of the oceans.

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Petroleum systems analysis and maturity modelling is used to predict the timing and locations of hydrocarbon generation in the underexplored offshore Zambezi Delta depression and Angoche basin, northern Mozambique. Model inputs include available geological, geochemical and geophysical data. Based on recent plate‐tectonic reconstructions and regional correlations, the presence of Valanginian and Middle and/or Late Jurassic marine source rock is proposed in the study area. The stratigraphy of the Mozambique margin was interpreted along reflection seismic lines and tied to four wells in the Zambezi Delta depression. Thermal maturity was calibrated against measured vitrinite reflectance values from these four wells. Four 1‐D models with calibration data were constructed, together with another five without calibration data at pseudo‐well locations, and indicate the maturity of possible source rocks in the Zambezi Delta depressions and Angoche basin. Two 2‐D petroleum systems models, constrained by seismic reflection data, depict the burial history and maturity evolution of the Zambezi Delta basin. With the exception of the deeply‐buried centre of the Zambezi Delta depression where potential Jurassic and Lower Cretaceous source rocks were found to be overmature for both oil and gas, modelling showed that potential source rocks in the remaining parts of the study area are mature for hydrocarbon generation. In both the Zambezi Delta depression and Angoche basin, indications for natural gas may be explained by early maturation of oil‐prone source rocks and secondary oil cracking, which likely began in the Early Cretaceous. In distal parts of the Angoche basin, however, the proposed source rocks remain in the oil window.