Plate kinematic modelling of the Atlantic and Arctic Oceans for conjugate margin studies

The Iberian and Newfoundland conjugate margins are undoubtedly some of the best
studied margins globally. Despite this, there is still very little consensus as to Iberia’s
Mesozoic position during its early stages of divergence from North America.
Inconsistencies in modelling early stages of plate divergence in this region stem from
the extensive transition zones bordering the southern North Atlantic Ocean.
Uncertainties in modelling the Iberian plate branch out of the region, making for more
complex and questionable regional frameworks in which to interpret geological events
in regions such as the Bay of Biscay or Pyrenees.

Using three newly acquired seismic profiles from the southern Newfoundland Basin I
assess the suitability of commonly used break-up markers (M-Series and J-Anomaly) for
plate kinematic reconstructions. Interpretations suggest crustal structure at times
coinciding with these breakup markers to comprise exhumed mantle with magmatic
additions of an unknown age. Although the events from which these break-up markers
originate immediately precede first seafloor spreading, they are neither instantaneous
in time nor isochronous along the margin. Taking this analysis one step further, I derive
potential seismic conjugates profiles using an already published seismic profile from the
conjugate Tagus Abyssal Plain. Conjugate pairing shows there is little benefit as to a
data versus model approach when deriving ‘conjugate’ profiles for the Iberia –
Newfoundland margins. To work around the Iberia problem I propose the creation of a
new, multi-plate circuit constraining the plates surrounding the smaller Iberian plate.

To test and validate the plate circuit approach I close the Atlantic – Arctic plate circuit
and test its outputs, the relative motions of the Greenland and North American plates
against magnetic anomaly data of the Labrador Sea region. This model provides a
regional context to study both divergent and convergent phases affect the SW
Greenland margin with quantified uncertainties attached to the model.

I go on to apply this proven plate circuit technique to the Iberia – Newfoundland
problem. By generating three new plate circuits using the African, Moroccan, Iberian
and North American plates I provide a statistically quantifiable context in which to
study the evolution of plate boundaries along the northern and southern Iberian
margins as well as in NW Africa. These findings provide rational as to modelling the
earliest stages of divergence between Iberia and Newfoundland.