29 January 2016 – Seminar

When: 15:00 on Friday, 29 January 2016
Where: DIAS, Geophysics Section, 5 Merrion Square, Dublin 2, (library)

Speaker: Marcel Cembrowski (Goethe University of Frankfurt)
Title: Anisotropic Asthenosphere under the Pyrenees – A 3-D Magnetotelluric Modeling Study of the Orogen

Abstract:

The Pyrenees have formed due to the convergence and the subsequent collision between the Iberian and European plates from Late Cretaceous to Early Miocene. The collision resulted in the subduction of the Iberian continental lower crust below the continental European crust. The electromagnetic signature of the Pyrenees can reveal a lot about its tectonic history and therefore Magnetotelluric studies play an important role in understanding the evolution of the orogen. We perform 3-D resistivity modeling of the orogen and its surrounding areas by fitting phase tensors and induction arrows. The data reveal a good conductive lithospheric body along the axial zone of the Pyrenees that we interpret as being the partial melt body found by prior studies. For periods >1000 s the data feature an enormous phase split with its minimum and maximum phase oriented perpendicular and parallel to the strike direction of the orogen. We show that the split is partly caused by the induction effect of the surrounding oceans, but an anisotropic asthenosphere is needed to fully explain the phase difference. We analyze the cause of anisotropy and relate it to present day plate motion.