Phase 4: Transcurrent motion along the Northern Pyrenean Fault

This phase comprises two stages, the first being associated to the time interval from chron M21 (147.7 Ma, Middle Tithonian) to chron M16 (139.6 Ma, Upper Berriasian), while the second one ranges between 139.6 Ma and anomaly M10 (131.9 Ma, Valanginian-Hauterivian boundary). The regional velocity field is illustrated in Figure 11. As anticipated in the previous section, seafloor spreading in the Central Atlantic is now linked to the kinematic pattern of the Tethyan realm via the NPF. No other major tectonic events occurred in the Tethyan realm during these two stages. However, the spreading rate in the southern Central Atlantic diminished significantly with respect to the previous phase, from about 46 mm/yr to 30 mm/yr. The onset of an early compressional setting in the Liguride Ocean and the renewal of tectonic activity at the southern boundary of Iberia marked the end of this phase at anomaly M10. The acceleration field that was responsible of this event is shown in Figure 12. In the Vardar Ocean, an eastward directed variation of velocity of Eurasia determined a faster spreading rate at the beginning of the successive phase.

Figure 11. Reconstruction at 131.9 Ma (Lower Hauterivian)

Reconstruction at 131.9 Ma (Lower Hauterivian)

Vectors represent direction and magnitude of the relative velocity field between conjugate pairs of plates. Blue lines represents the modeled 172.0 Ma, 170.0 Ma, M25, M21 and M16 isochrons. The location of the Euler pole of relative convergence between Vardar and Eurasia is marked by a small empty circle.

Figure 12. Acceleration field at 131.9 Ma (Lower Hauterivian)

Acceleration field at 131.9 Ma (Lower Hauterivian)

Vectors represent direction and magnitude of the relative acceleration field of Africa with respect to Iberia and Eurasia with respect to Africa.