Seminář – Thomas Meier (University Kiel)

Imaging drivers of plate deformation in the Circum-Mediterranean

Thomas Meier (University Kiel, Germany)

Since the Lower Cretaceous, the Mediterranean – located between the converging Eurasian and African Plates – has been characterized by intense tectonic activity including orogenic belts, volcanism, and back-arc extension. Subduction of several oceanic basins in small-scale, strongly curved subduction zones resulted in highly time-variable plate configurations. Additionally, the size of the continental Adriatic Plate as promontory of the African Plate has been reduced by about 75 percent leaving only an about 200 km wide remnant beneath the Adriatic Sea undeformed. While the importance of oceanic subduction for the tectonic development of the Mediterranean has been recognized since the late 1970s, the driving forces for continental subduction and associated plate deformation remain a matter of debate. Passive seismic imaging of the lithospheric architecture of orogenic belts and of slabs in the uppermost mantle is key for the understanding of these processes. The current knowledge of the orogenic deep structure in the Mediterranean is reviewed, recent contributions by surface wave tomography are presented, and the relation between lithospheric thickness and intraplate volcanism is discussed. A brief introduction to AdriaArray, an initiative to obtain data for passive seismic investigation of the central Mediterranean, is given. Sedimentation, rifting, uplift, as well as Cenozoic volcanism are evidence that also the Eurasian lithosphere in central Europe is prone to considerable plate deformation. A model for the Mesozoic and Cenozoic evolution of continental lithosphere in the region accounting for dynamic lithosphere-asthenosphere interactions is discussed.

Figure: Vertical cross section of a 3D shear-wave velocity model obtained from surface wave tomography (El-Sharkawy et al., 2024) showing the variable lithosphere-asthenosphere system along a profile from the Paris Basin in the west to the East European Craton in the east. Triangles indicate intraplate volcanism.