INVESTIGATING THE PLATE KINEMATICS OF THE BAY OF BISCAY USING DEFORMABLE PLATE TECTONIC MODELS

The ongoing debate regarding the Iberian plate kinematics during rifting and subsequent opening of the southern North Atlantic has caused uncertainties to arise when investigating the plate kinematics of the Bay of Biscay. Constrained by previous plate reconstruction, and independent geophysical and geological studies, deformable plate tectonic reconstructions of the Bay of Biscay-Parentis rift system are built in this study using the GPlates software. These deformable plate models are used to investigate the plate kinematics of the Landes High, Le Danois High, and Ebro Block as independent continental blocks within deformable regions from 200 Ma to present day. Following a comparison of present day crustal thickness results calculated by deformable plate models with previously published and newly presented gravity inversion crustal thickness estimates, a preferred plate kinematic model of the Bay of Biscay is proposed. This preferred plate kinematic model implies a transtensional Bay of Biscay-Parentis rift system from the Jurassic to Early Cretaceous, with the main rift phase initiating during the Late Jurassic subsequently evolving into hyperextension during the Early Cretaceous related to the independent motion of the Landes and Le Danois High. In addition, the timing and extent of deformation experienced within the Bay of Biscay suggested by deformable plate models is analyzed in comparison with that derived from previously published interpretations of seismic and well data. This investigation provides valuable insight regarding the kinematic role of continental blocks during rifting. In particular, their importance on the distribution of sub-basins and strain partitioning, and their interplay with inherited structures and horizons during formation of the Bay of Biscay.