In this study, ten newly acquired long-offset multichannel seismic profiles extending across the western Porcupine Bank margin, combined with potential field data, are used to investigate the crustal architecture, tectonic history, and rift-related magmatism along the margin. While the offshore Irish Atlantic margin and related rift basins have been intensively studied for several decades, the Porcupine Bank, straddling between the well-studied Porcupine and Rockall basins, is a poorly understood region due to lacking sufficient geophysical data coverage. The final locally updated plate model supports the hypothesis of compartmentalization of the continental region of the Goban Spur margin, highlights the significant role of inherited structures, and renews linkages between the Goban Spur and its potential conjugates during oblique rifting. The present-day crustal thicknesses on the Goban Spur from the locally updated plate model agree with those derived from gravity inversion, providing a possible remedy for the crustal thickness discrepancy generated by existing models. In addition, the seismic reflection data are used to assist in adjusting the geometry of the modelled zone of deformation on the Goban Spur. More importantly, the seismic reflection data show zones of focused faulting, which are incorporated into the plate model as inherited weakness zones. The new long-offset seismic reflection data reveal the complex architecture of the Goban Spur basins, which are filled with highly variable sediment thicknesses, suggestive of a protracted and polyphased rifting history. This study seeks to resolve this discrepancy by locally updating an existing plate model of the southern North Atlantic by incorporating constraints from four newly-presented seismic reflection profiles. Specifically, crustal thicknesses calculated for the Goban Spur from existing plate models show a discrepancy with those derived from independent geophysical methods like gravity inversion and seismic refraction modelling. To date, kinematic plate reconstruction models have struggled to restore the tectonic evolution of the Goban Spur, offshore Ireland. In total, five distinct crustal zones related to different rifting stages are identified and their regional extents are evaluated, providing a more detailed characterization of this margin. Magmatic contributions are interpreted to increase from NW to SE, based on contrasting basement characteristics observed on the seismic profiles. Toward the southeast, the zone of peridotite ridges pinches out. In the northwest, the transitional zone between oceanic crust and stretched continental crust consists of a narrow zone of shallow peridotite ridges and a wider zone of the deeper exhumed serpentinized mantle, much like the conjugate Iberian and Newfoundland margins. These seismic profiles reveal significant along-strike structural variations along the Goban Spur margin, suggestive of different extension rates, rifting styles and stages. Here, six newly acquired multi-channel seismic reflection lines are processed and interpreted, along with vintage seismic profiles, to characterize its structure and evolution. The crustal architecture of the margin is complicated due to its multi-staged tectonic history. However, the along-strike extent of this serpentinized zone has, until now, been unknown due to insufficient data coverage. Published studies demonstrated that a 70-km-wide zone of exhumed serpentinized mantle lies between oceanic crust and stretched continental crust at the seaward limit of Goban Spur. The Goban Spur, offshore Ireland, is a magma-poor rifted continental margin conjugate to the well-studied Newfoundland margin, offshore Canada.

Free goban windows