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

Olivia A Walker,Tiago M Alves,Stephen P Hesselbo,Tim Pharaoh,M Nuzzo,Nathalia H Mattos

doi:10.1016/j.marpetgeo.2020.104705

Olivia A Walker, Tiago M Alves + Show 4 more

Open Access

https://doi.org/10.1016/j.marpetgeo.2020.104705

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Abstract

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.

Highlights

Extensive seaways can form during continental rifting, providing a marine passage between two pre-existing oceans (Korte et al, 2015)
The data in this study reveals that Triassic–Early Jurassic continental rifting in the North Atlantic coincides with the establishment of a ~200 km wide seaway in West Iberia
New reprocessed data and tectonic subsidence curves for the Lusitanian, Porto and Peniche basins, West Iberia, reveal the palaeo-position and width of this Triassic-Early Jurassic seaway, which was divided in two distinct sectors

Summary

Introduction

Extensive seaways can form during continental rifting, providing a marine passage between two pre-existing oceans (Korte et al, 2015). The Hispanic Corridor is another such seaway developed in the Early Jurassic, and provided a connection between the Palaeo-Pacific and the western Tethys Ocean This corridor was likely established between North America, South America and Africa as early as the Hettangian based on the analysis of mixed bivalve fossil populations occurring in these three continents (Sha, 2002). It is one of the few Jurassic seaways described in the literature that is clearly associated with the breakup of the supercontinent Pangea. Younger seaways include: 1) the Red Sea, which has provided a connection between the Indian and the Atlantic Ocean via the Mediterranean Sea since the Late Paleogene (Gerges, 2002), and 2) the Arctic Gateway, which forms a connection between the Pacific and the Arctic Ocean since, at least, the Late Miocene (Marincovich and Gladenkov, 1999; Woodgate and Aagaard, 2005)

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