Orogenic lithosphere and slabs in the greater Alpine area – interpretations based on teleseismic P-wave tomography

Abstract. Based on recent results of AlpArray, we propose a new model Alpine collision that involves subduction and detachment thick (∼ 180 km) European lithosphere. Our approach combines teleseismic P-wave tomography existing local earthquake (LET), allowing us to image the slabs their connections with overlying orogenic lithosphere at an unprecedented resolution. The images call into question conventional notion downward-moving comprise only seismically fast We is heterogeneous, locally containing layered positive negative Vp anomalies up 5 %–6 %. attribute this heterogeneity seismic anisotropy and/or compositional differences inherited from Variscan pre-Variscan cycles rather than thermal anomalies. lithosphere–asthenosphere boundary (LAB) Plate therefore lies below conventionally defined seismological LAB. In contrast, Adriatic thinner has lower approximately base strong 100–120 km. Horizontal vertical tomographic slices reveal beneath central western Alps, slab dips steeply south southeast still attached However, in eastern Alps Carpathians, completely detached crust north northeast. This along-strike change attachment coincides abrupt decrease Moho depth Tauern Window, being underlain by pronounced anomaly reaches eastward Pannonian Basin area. interpreted as representing hot upwelling asthenosphere heated crust, it accommodate Neogene orogen-parallel lateral extrusion thinning ALCAPA tectonic unit (upper plate crustal edifice Carpathians) east. A origin northward-dipping, segment likely since its down-dip length matches estimated Tertiary shortening accommodated originally south-dipping Dinarides There no evidence Alps. Northern Apennines, also origin, hangs subvertically Apenninic foreland. Except for northernmost where overlies southern end clearly separated latter broad zone low velocities located Po Basin. Considered whole, chain are highly attenuated, largely sheets continental margin Tethyan oceanic reach down graveyard mantle transition (MTZ).