From underplating to delamination-retreat in the northern Apennines
- Autor(en)
- Claudio Chiarabba, Jenny Giacomuzzi, Irene Bianchi, Nikola Agostinetti Piana, Jeffrey Park
- Abstrakt
Recordings of teleseismic earthquakes from a dense set of temporary and permanent broadband seismic stations reveal the lithospheric structure of the northern Apennines and support the scenario of a retreating detachment within the mid-crust. Lithospheric delamination appears crucial to the formation and evolution of the Apennines orogen. Receiver-function (RF) stacks outline a continuous west-dipping Ps converted phase from a positive velocity jump that we interpret as the top of the lower crust and mantle of the Adria continental lithosphere, which is descending into the shallow mantle. The correlation of seismicity with two RF profiles across the northern Apennines suggests distinct stages of lithospheric delamination. Active penetration of the detachment into the Adria lithosphere seems evident in the south/east, with induced shallow-mantle flow facilitated by slab dehydration. Penetration of the detachment in the north/west seems to have arrested, and is possibly marked by crustal underplating. This layer atop the Apennines slab is visible only down to 80 km depth and suspends above an oppositely-dipping paired positive/negative Ps converted phase in stacked receiver functions. The break in the west-dipping Adria lithosphere conflicts with a westward-subduction scenario continuous from the Oligocene. Lateral changes of deep structure and seismicity along the northern Apennines suggest that underplating of crustal material and delamination-retreat are distinct mechanisms active today in the western and eastern sectors, respectively, of the northern Apennines. Negative Ps-pulses at 100-120 km depth help to define a seismic lithosphere-asthenosphere boundary (LAB), but cross-cut a volume of high-velocity mantle rock, as inferred from tomographic models. We hypothesize that this seismic LAB is a rheological discontinuity that affects the frequency band of seismic body waves, but not the long-term viscous response that governs the evolution and eventual detachment of the continental slab.
- Organisation(en)
- Institut für Meteorologie und Geophysik
- Externe Organisation(en)
- Istituto Nazionale di Geofisica, Roma, Istituto Nazionale di Fisica Nucleare (INFN), Roma, Dublin Institute for Advanced Studies, Yale University
- Journal
- Earth and Planetary Science Letters
- Band
- 403
- Seiten
- 108-116
- Anzahl der Seiten
- 9
- ISSN
- 0012-821X
- DOI
- https://doi.org/10.1016/j.epsl.2014.06.041
- Publikationsdatum
- 10-2014
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105102 Allgemeine Geophysik
- Schlagwörter
- ASJC Scopus Sachgebiete
- Geochemistry and Petrology, Geophysics, Earth and Planetary Sciences (miscellaneous), Space and Planetary Science
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/be4a4bf7-2085-4787-ae1f-186ceb0e785b