Seismic evaluation of the Flemish Cap and Goban Spur pre-rift relationship prior to the opening of the North Atlantic, with support from plate reconstruction
Abstract. Recent geophysical investigations of the NE Newfoundland-Irish Atlantic rifted margin pair (North Atlantic) have called into question the previously assumed conjugate relationship and rift-perpendicular extension between the Flemish Cap and Goban Spur. In this study, we present multichannel seismic reflection profiles across the margins of the Flemish Cap, Porcupine Bank, and Goban Spur, and define their structural domains (proximal, necking, hyperextended, and/or exhumed mantle domains), which display varying degrees of asymmetry along strike. Observed intra-crustal reflectivity patterns are interpreted to be related to Paleozoic orogeny and/or orogenic collapse prior to the major Mesozoic rifting, consistent with this rift system having been strongly influenced by inherited Appalachian-Caledonian and Variscan structures. Reflective features within each structural domain are strikingly different across both margins, however similarities are most pronounced for the necking domains of the Porcupine Bank and Flemish Cap, which is consistent with a connection between the Porcupine Bank and Flemish Cap during Early Jurassic rifting. This inference is compatible with recently published deformable plate reconstruction models, which are used herein to relocate and reconstruct the representative seismic sections back through time to the onset of rifting. The changes of paleo-positions and geometric shapes of the seismic sections in deformable plate reconstruction models over time further show complicated 3D plate kinematics for the NE Newfoundland-Porcupine Atlantic margins, highlighting interplay of inherited structures, oblique extension, and poly-phase margin evolution between the Porcupine Bank, Goban Spur, and Flemish Cap and their intervening rift basins during the southern North Atlantic opening.
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