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| Mesozoic rifting | |
|---|---|
| Name | Mesozoic rifting |
| Era | Mesozoic |
| Main locations | Pangea margins, North Atlantic, South Atlantic, North America, Europe, Africa |
| Time period | Triassic–Cretaceous |
| Processes | continental rifting, break-up, basin formation, magmatism |
Mesozoic rifting Mesozoic rifting denotes the widespread episode of continental extension, lithospheric breakup, and basin formation that accompanied the fragmentation of Pangaea during the Triassic, Jurassic, and Cretaceous, linking processes active along the future margins of North America, South America, Africa, Eurasia, and Antarctica. This tectonic episode produced rift basins, passive margins, flood basalts, and transform systems that influenced the distribution of sedimentary environments, the emplacement of igneous provinces, and the geographic context for paleontological assemblages such as those found in Solnhofen, La Brea Tar Pits, and the Hell Creek Formation.
Mesozoic rifting initiated as intra-continental extension across the supercontinent Pangaea and progressed to oceanic spreading that created the Atlantic Ocean, the Indian Ocean, and peripheral basins adjacent to Gondwana and Laurasia. Key large-scale tectonic reorganizations during the reign of Triassic, Jurassic, and Cretaceous stages produced linear rift provinces such as the Central Atlantic Magmatic Province associated with the initial opening between North America and Africa. Continental rift systems evolved into passive continental margins exemplified by the eastern margin of North America and the western margin of Africa.
Drivers of Mesozoic rifting included intraplate tensional stresses related to mantle convection beneath the lithosphere documented in studies of the Iberian Peninsula, plume-related upwelling inferred beneath the Central Atlantic Magmatic Province, and far-field forces caused by plate reorganizations at the margins of Gondwana and Laurasia. Mantle plume hypotheses often appeal to candidates such as the proto-Iceland-scale upwellings that contributed to voluminous magmatism and weakening of continental lithosphere. Strike-slip reactivation of pre-existing suture zones and the influence of Neoproterozoic shear zones in regions like the North China Craton and the West African Craton localized rift initiation.
Notable Mesozoic rifted domains include the Central Atlantic rift system that produced basins along the coasts of Maryland, Nova Scotia, and Morocco; the North Atlantic rift responsible for the formation of basins offshore of Greenland and Norway; the South Atlantic rift separating Brazil and Angola; and the East African–Gondwana linkages affecting Madagascar and India. Individual basins illustrate diversity: the Newark Basin in the eastern United States and adjacent basins in Nova Scotia record Triassic–Jurassic lacustrine deposits, the Lusitanian Basin in Portugal preserves marine transgressions, and the Karoo Basin in South Africa documents extensive sediment fill and magmatic interactions.
Rifting progressed through several stages: pre-rift thermal uplift and crustal thinning during the Late Triassic, syn-rift fault-bounded subsidence with sediment accumulation in the Jurassic, and post-rift thermal subsidence and passive-margin development through the Cretaceous. Chronostratigraphic markers such as Triassic continental redbeds, Jurassic marine transgressions recorded in the Kimmeridgian and Tithonian, and Cretaceous chalk and carbonate deposits provide temporal constraints. Radiometric dating of flood basalts and intrusive complexes in provinces like the Central Atlantic Magmatic Province and the Paraná–Etendeka flood basalts refines the timing of rift-related magmatism.
Magmatism accompanying Mesozoic rifting ranged from basaltic flood eruptions producing large igneous provinces—e.g., the Central Atlantic Magmatic Province and the Paraná–Etendeka—to intrusive rift-related sills and dykes documented in the Karoo and North Sea regions. Syn-rift sedimentation produced alluvial, fluvial, lacustrine, and restricted marine sequences that later became hydrocarbon-bearing units in basins such as the Gulf of Mexico, the Campos Basin, and the North Sea. Rift-driven volcanism influenced sediment provenance and diagenesis, with volcaniclastics preserved in formations like the Deccan-related successions and coeval sequences in the Indian subcontinent.
Mesozoic rift basins host significant hydrocarbon systems, with source rocks, reservoirs, and traps developed in the rift-to-passive-margin transect of locations such as the North Sea, the Gulf of Mexico region, the Campos and Santos basins off Brazil, and the West African margin near Gabon. Rift-related magmatic intrusions created mineral systems including Ni–Cu–PGE sulfide deposits in rift-hosted complexes and geothermal resources in extensional provinces. Sedimentary fill in rift basins also preserves coal seams and evaporite deposits that have been economically exploited in regions like Germany and Spain.
The geographic reconfiguration driven by Mesozoic rifting modified ocean circulation, climate gradients, and habitat connectivity, influencing the distribution and evolution of marine faunas documented in the Solnhofen Limestone and terrestrial faunas such as early Dinosauria assemblages across rift basins in North America, China, and Argentina. Sea-level changes induced by basin subsidence and global eustatic shifts affected carbonate platform development along margins like the western Europe shelf. Volcanism and greenhouse gas fluxes associated with large igneous provinces contributed to climatic perturbations that coincide with biotic crises and radiations recorded in stratigraphic boundaries preserved in many Mesozoic basins.