Investigating the role of the Galicia Bank on the formation of the North West Iberian margin using deformable plate tectonic models

Abstract

The kinematic evolution of the West Iberian margin during the opening of the southern North Atlantic has been of interest for several decades and provides a well-constrained environment to study and develop new concepts related to the formation of non-volcanic (magma poor) passive margins. Building upon previous rigid and deformable plate tectonic modelling studies, the aim of this work is to create deformable plate tectonic models of the West Iberian margin using previously published constraints in GPlates to investigate the role of the Galicia Bank as an independent continental ribbon during deformation of the West Iberian margin from 200 Ma to present day. A comparison of present day crustal thickness results calculated from deformable plate tectonic reconstructions with those obtained from gravity inversion has allowed the plate kinematics of the Galicia Bank relative to the Flemish Cap to be investigated. Additionally, this comparison provided detailed insights into the most probable kinematic scenarios for the Galicia Bank continental ribbon, including its impact on the deformation experienced within the Galicia Interior Basin. Two preferred kinematic models for the Galicia Bank are proposed. One that implies synchronous motion with the Flemish Cap until ~160 Ma after which the Galicia Bank begins to move southward, causing crustal thinning within the Galicia Interior Basin. The other preferred model, despite its discrepancies with gravity inversion results, implies synchronous motion of the Galicia Bank and southeastern Flemish Cap until breakup between the southeastern Newfoundland and Iberian margins initiating ~140 Ma. In addition to the deformation induced by the motion of the Galicia Bank, this study demonstrates the influence of inherited Variscan structures and their impact on rift segmentation experienced within the Galicia Interior Basin. This is inferred through attempts to discretize triangular meshes within regions of deformation in areas where inherited structures have been previously interpreted.