Seismic anisotropy beneath southern Iberia from SKS splitting

摘要: Abstract Seismic anisotropy of the south Iberian upper mantle is investigated using shear-wave splitting SKS phases. We analyzed teleseismic events recorded by sixteen permanent broadband stations installed on southern Peninsula and in northern Africa, we determined fast polarization directions ϕ, delay times δ t between slow components. The area investigation extends across two important geological structures Variscan Peninsula: Massif its center, Gibraltar arc Southeast, that represents most westerly Alpine belt western Mediterranean. Shear-wave measurements from Betic domain show homogeneous ENE–WSW nearly parallel to trend mountain belt, smooth spatial variations. Stations North, toward part however trending NS NE–SW, different those Betic. These observations may reflect a post-Hercynian (Variscan) deformation Ossa-Morena zone, related main stages tectonic evolution this part, namely transpressional stage, transtensional stage shortening episode, or posterior orogeny. Along arc, observe smoothly varying ϕ changing Eastern Betics Ceuta, following more less general around Alboran Sea, coastline. Since similar rotation also visible results Pn anisotropy, suggests vertically coherent starting just below Moho. Comparing pattern expected various geodynamic models with observed best explained model slab rollback, rather than delamination models.