Triple junctions of Bay of Biscay and North Atlantic; new constraints on the kinematic evolution

Recently surveyed triple junction trajectories in the Bay of Biscay and newly available magnetic maps constrain the early oceanic evolution of the North Atlantic and Bay of Biscay from chrons M0 to A33o (118 to 80 Ma). The opening of the Bay of Biscay is of the scissors-opening type with a pole of rotation located near Bordeaux (lat 44.6 degrees N, long 0.3 degrees W) and predicted simultaneous compression in the central and eastern Pyrenees. Structural directions west of Iberia do not fit the North America-Iberia motion. Therefore, a second triple junction, of the ridge-ridge-fault type, is postulated just south of the first one, which propagated north-ward from a more southerly position.