Investigating the role of continental blocks and their interplay with the Iberia, Newfoundland and Irish offshore margins using plate tectonic reconstructions

King, Michael (2023) Investigating the role of continental blocks and their interplay with the Iberia, Newfoundland and Irish offshore margins using plate tectonic reconstructions. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Rifted margins encompass significant architectural variabilities and represent a transition zone between Earth’s continents and oceans. Due to the abundance of natural resources that are hosted within their overlying sedimentary basins (e.g., hydrocarbons, carbon-capture targets, geothermal reservoirs, mineral deposits, and natural hydrogen), rifted margins are also highly influential regions for meeting our planet’s energy needs. Furthermore, the structure and morphology of rifted margins during compressional re-activation can have a significant impact on the closure of oceans and the creation of continental landmasses. As a result, investigations that aim to explore their present-day architecture and the processes responsible for their formation are significantly important. The Newfoundland, Irish, and Iberian rifted margins represent some of the best studied examples of rifted margins in the world. However, despite being relatively well-studied, their complex present-day crustal structure has made it difficult to unravel their plate kinematic history and crustal evolution. As well, the majority of previously published plate reconstruction studies within these regions have primarily focused on the kinematics of large, rigid tectonic plates, ignoring the fact that tectonic plates are often significantly deformed and partitioned into micro-plates and smaller continental blocks over geological time. In this thesis, deformable plate tectonic reconstructions that account for 3-D kinematics and deformation are used to investigate the plate kinematic role of continental blocks (e.g., Flemish Cap and Galicia Bank) and their interplay with the Iberian micro-plate during the opening of the southern North Atlantic Ocean. A collection of deformable plate modelling investigations focussed iii on Iberia’s present-day offshore continental margins (West Iberian margin and Bay of Biscay), and former margins that have been re-activated by compressional deformation (e.g., Pyrenees and Iberian Ranges) provide a comprehensive assessment of Iberia’s plate kinematic history and the influential role of continental block kinematics. In addition, this thesis introduces new deformable plate tectonic modelling workflows that can be used to reduce their geologically unsatisfying assumptions and make quantitative comparisons between their results (e.g., crustal thickness and extension estimates) and similar, but independently obtained, estimates calculated using methods such as 2-D structural restorations of seismic interpretations. The application of these newly presented workflows to study the formation of the Newfoundland, Irish, and West Iberian margins provides new insights into the partitioning of deformation within continental blocks, their potential origin, and their interplay with inherited structures during rift-related deformation experienced within neighbouring sedimentary basins.

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