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| Titel |
Crust-mantle decoupling in the Alps, Carpathians, Dinarides and Hellenides - the next targets of AlpArray? |
| VerfasserIn |
Mark R. Handy, Eduard Kissling, Wim Spakman, Kamil Ustaszewski, Eline Le Breton, Joerg Giese |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250153106
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| Publikation (Nr.) |
 EGU/EGU2017-18044.pdf |
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| Zusammenfassung |
| The junctions of the Alps, Carpathians, Dinarides and Hellenides have disparate subsurface and surface structures that indicate decoupling of the crust and lithospheric mantle during Adria-Europe convergence. The complexity of subsurface structures at these orogenic junctions make them inviting targets for the next generation of integrated seismological-structural studies.
Travel-time and receiver-function tomography at the Alps-Carpathians junction suggest that the NE-dipping “Lippitsch” positive anomaly beneath the Eastern Alps may connect eastward to a subvertical positive anomaly reaching down to the Mantle Transition Zone beneath the Pannonian Basin. The length of this slab-like anomaly exceeds known Neogene shortening in the overlying crust which is masked by Miocene Pannonian upper-plate extension. This suggests that either Neogene N-S shortening in the eastern Alps, western Carpathians and northern Dinarides has been underestimated and/or that this anomaly is an amalgam of subduction of both European and Adriatic lithospheres; these may have melded during a Miocene switch in subduction polarity beneath the eastern Alps. Neogene crustal deformation north of the Periadriatic Fault in the Tauern Window (Austria) involved north-directed crustal wedging and eastward orogenic escape, whereas south of this fault deformation involved large (≤ 130°) clockwise block rotations, S-directed thrusting and overturned Eocene Dinaric thrusts (Medvenica mountains, northern Croatia).
Most global P-wave tomographic models indicate no Adriatic slab anomaly in the northern Dinarides and only a short (≤ 150 km long) NE-dipping anomaly in the southern Dinarides. The short length probably reflects the obliquity of Neogene Adria-Europe convergence, whereas the lack of an anomaly may be due to thermal erosion during asthenospheric flow since late Paleogene slab delamination or breakoff.
At the Dinarides-Hellenides junction, the NE-dipping Adriatic slab has retreated SW-ward since this breakoff event, as indicated in cross sections by offset between the slab anomaly and the Sava suture. This junction is marked by orogen-parallel and –normal extension, and clockwise block rotation localized along a normal fault oriented transverse to the orogen (Shkoder-Peja Normal Fault, SPNF). Faulting has been active since mid-Miocene time according to clastics in the hangingwall of the SPNF, earthquake focal mechanisms and GPS motion vectors. The junction has been interpreted as a hinge zone at the NW end of the Hellenic arc that links arc-parallel extension to Adriatic subduction during radial expansion of the SW-retreating Hellenides. |
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