Assessing the Rotation and Segmentation of the Porcupine Bank, Irish Atlantic Margin, During Oblique Rifting Using Deformable Plate Reconstruction

• Published in: Tectonics (Washington, D.C.) D.C.), 2021-12, Vol.40 (12), p.n/a
• Main Authors: Yang, Pei, Welford, J. Kim, King, Michael T.
• Format: Article
• Language: English
• Subjects: Crustal deformation; Crustal thickness; deformable plate reconstruction; Deformation; Gravity; Inheritances; Modelling; oblique rifting; Obliquity; poly‐phased rotation; Porcupine Bank; Restoration; rift segment; Rifting; Rotation; Seismic data; Seismological data; structural inheritance
• ISSN: 0278-7407; 1944-9194
• DOI: 10.1029/2020TC006665

Published plate reconstructions have provided insights regarding the formation of the North Atlantic, in which the motion of the Porcupine Bank, on the Irish Atlantic margin, underlain by orogenic pre‐rift crustal basement terranes, is investigated and restored. Previous reconstructions of the Porcupine Bank mainly relied on potential field data rather than seismic constraints and failed to reveal the role of inherited crustal terranes during rifting and subsequent crustal deformation. In this study, five deformable plate tectonic models with distinct structural inheritance trends are established in GPlates by adjusting a previously published restoration model for the North Atlantic. For each model, driving factors such as the inclusion of the Orphan Knoll, the Flemish Cap poles of rotation, and the motion of the eastern border of the Porcupine Basin are also considered. To assess the validity of deformable plate models, crustal thickness estimates obtained from gravity inversion and seismic data modeling are compared with those calculated via deformable plate models. The preferred deformable plate model proposes the subdivision of the Porcupine Bank into four blocks with each block experiencing poly‐phased rotation and shearing prior to the final continental breakup, implying strong inheritance and segmentation of the Porcupine Bank and Porcupine Basin. The reconstructed paleo‐positions of the Flemish Cap and Porcupine Bank within deformable regions reveal evolving conjugate relationships during rifting, which are assessed using regional seismic transects from both margins. Finally, extensional obliquity between both margins is quantitatively restored, showing time‐variant orientations due to the rotation and shearing of associated continental blocks. Key Points The Porcupine Bank experienced rotation and shearing during oblique rifting, strongly influenced by the inherited Caledonian sutures Crustal thickness between the Flemish Cap‐Porcupine Bank pair is quantitatively restored over time based on the deformable plate model Extension obliquity between the Porcupine Bank and Flemish Cap varies over time, accompanied by segmentation of the Porcupine Basin