Kinematic plate modelling of the Goban Spur margin, offshore Ireland, with deforming zones constrained by seismic reflection data

Abstract

To date, kinematic plate reconstruction models have struggled to restore the tectonic evolution of the Goban Spur, offshore Ireland. 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. 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. 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. More importantly, the seismic reflection data show zones of focused faulting, which are incorporated into the plate model as inherited weakness zones. In addition, the seismic reflection data are used to assist in adjusting the geometry of the modelled zone of deformation on the Goban Spur. 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. 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.