A tectono-stratigraphic review of continental breakup on intraplate continental margins and its impact on resultant hydrocarbon systems

• Published in: Marine and petroleum geology 2020-07, Vol.117, p.104341, Article 104341
• Main Authors: Alves, Tiago, Fetter, Marcos, Busby, Cathy, Gontijo, Rogerio, Cunha, Tiago A., Mattos, Nathalia H.
• Format: Article
• Language: English
• Subjects: Continental breakup; Continental margins; Hydrocarbons; Sedimentation; Structure; Subsidence
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2020.104341

Intraplate Continental Margins comprise fully rifted areas of continents and cratons recording the tectonic events associated with plate breakup and subsequent continental drift. In contrast to extensional basins, this tectonism post-dates the initial stages of continental rifting of tectonic plates and is specifically associated with the breakup and ‘drifting’ of continents. Seismic and outcrop data from eight (8) Intraplate Continental Margins are reviewed in this work and tectonic-subsidence models are compiled to highlight their large-scale structural and depositional variability. Specific geological aspects that enhance the hydrocarbon potential of Intraplate Continental margins include: a) syn-rift strata that are strikingly thicker, and presumed older, than previously assumed on vintage seismic profiles, b) an important control of basement type and fabric on tectonic subsidence and subsequent reactivation after continental breakup is achieved, and c) widespread extensional collapse accompanying the continental breakup process to generate a phase of important sediment bypass into relatively deeper, distal depocentres. There is evidence on seismic data that the continental breakup process per se overprints older syn-rift structures to create a complex mosaic of uplifting and subsiding basins that may not coincide in location and extent with early syn-rift depocentres. This character has the potential of generating vast amounts of reservoir strata during tectonically active periods, at the same time enhancing the influx of organic matter to basins distant from point-sources of sediment during continental breakup. As a corollary, a classification of breakup sequences is presented in this work and a new case-study from South California is developed to acknowledge the varied hydrocarbon-generating settings of Intraplate Continental Margins when continental breakup is established. •Intraplate Continental Margins comprise fully rifted areas of continents and cratons.•They record the tectonic events specifically associated with plate breakup and continental drifting.•Syn-rift strata on Intraplate Continental Margins are strikingly thicker than previously assumed.•There is an important control of basement type and fabric on tectonic subsidence after continental breakup.•Widespread extensional collapse accompanies the continental breakup process, triggering sediment bypass.