Significance of Upper Triassic to Lower Jurassic salt in the identification of palaeo-seaways in the North Atlantic

• Published in: Marine and petroleum geology Vol. 123; p. 104705
• Main Authors: Walker, Olivia A., Alves, Tiago M., Hesselbo, Stephen P., Pharaoh, Tim, Nuzzo, M., Mattos, Nathalia H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2021
• Subjects: Continental rifting; Depositional facies; Early Jurassic; North atlantic; Seaways; Subsidence curves; Early Jurassic; Continental rifting; North atlantic; Seaways; Subsidence curves; Depositional facies
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2020.104705

This work uses high-quality reprocessed 2D data, tied to borehole information, to address the development of North Atlantic Jurassic seaways on the continental margin of West Iberia. The seismic data reveal the full thickness of Mesozoic syn-rift strata filling deep-offshore basins in this latter region. Tectonic subsidence resulted in the separation of the seaway into distal and proximal sectors. As a result, backstripped curves for West Iberia document important tectonic subsidence during the Late Triassic-earliest Jurassic. The Lusitanian and Peniche basins were part of the same seaway during the early stages of rifting, with important rift-shoulder exhumation occurring between the seaway and the distal margin from Late Jurassic onwards. We estimate 5 km subsidence in the deep-offshore Peniche Basin during the Late Triassic-Early Jurassic when compared to the ~1.1 km recorded in the proximal Lusitanian Basin. Critically, borehole stratigraphy shows that early Mesozoic basins in West Iberia, Newfoundland, and the North Sea show a tripartite depositional evolution of stacked continental, evaporitic, and marine strata. The similar Early Triassic-Jurassic seismic and stratigraphic records of the Lusitanian and Peniche basins suggest a co-genetic evolution with other early Mesozoic basins along the North Atlantic margin.