The Lithosphere-Asthenosphere System in the Calabrian Arc and Surrounding Seas - Southern Italy.

A fairly detailed structural model of the lithosphere-asthenosphere system (thickness, S- and P-wave velocities of the crust and of the uppermost mantle layers) has been defined in the Calabrian Arc region (Southern Tyrrhenian Sea, Calabria and the northwestern part of the Ionian Sea) in Southern Italy using seismic data from literature as a priori constraints of the nonlinear inversion of surface-wave data. The main features identified by this study are: (1) A very shallow (less then 10 km deep) crust-mantle transition in the Southern Tyrrhenian Sea and a very low vs just below a very thin lid, in correspondence of the submarine volcanic bodies Magnaghi, Marsili and Vavilov, while the vs in the lid is quite high in the area that separates Marsili from Magnaghi-Vavilov; (2) a shallow and very low vs layer in the uppermost mantle in the areas of the Aeolian Islands, Vesuvius, Phlegraean Fields and Ischia, which represents their shallow-mantle magma source; (3) a thickened continental crust and lithospheric doubling in Calabria; (4) a crust about 25-km thick and a mantle velocity profile versus depth consistent with the presence of a continental rifted lithosphere, now thermally relaxed, in the investigated part of the Ionian Sea; (5) the subduction towards northwest of the Ionian lithosphere below the Southern Tyrrhenian Sea; (6) the subduction of the Adriatic/Ionian lithosphere underneath the Vesuvius and Phlegraean Fields

Tomographic Study of the Adriatic Plate

4Two well-known methodologies have been used, for the first time, to derive a detailed and reliable lithospheric model of the Adriatic Plate, consistent with the thus far available data: non linear inversion of phase and group velocity dispersion curve obtained from surface-wave tomography, and body-waves tomography. To carry out the body-waves tomography, about 16500 P phases and 2000 S phases from 1219 seismic events, 73 seismic stations located at the border of the investigated region and a vertically heterogeneous starting model derived from the nonlinear inversion of average dispersion measurements, are used. The 3-D velocity model of the upper lithosphere, obtained from the combined analysis, shows a rather clear structural anomaly on the northeastern side, where the crust is thicker, and an uprising of the top of the lid in the northern part of the plate with a very thin, if any, transition zone from crust to mantle.nonemixedVENISTI N.; CALCAGNILE G.; PONTEVIVO A.; PANZA G.Venisti, N.; Calcagnile, G.; Pontevivo, A.; Panza, Giulian

The lithosphere-asthenosphere: Italy and surroundings

The velocity-depth distribution of the lithosphere-asthenosphere in the Italian region and surroundings is imaged, with a lateral resolution of about 100 km, by surface wave velocity tomography and non-linear inversion. Maps of the Moho depth, of the thickness of the lithosphere and of the shear-wave velocities, down to depths of 200 km and more, are constructed. A mantle wedge, identified in the uppermost mantle along the Apennines and the Calabrian Arc, underlies the principal recent volcanoes, and partial melting can be relevant in this part of the uppermost mantle. In Calabria a lithospheric doubling is seen, in connection with the subduction of the Ionian lithosphere. The asthenosphere is shallow in the Southern Tyrrhenian Sea. High velocity bodies, cutting the asthenosphere, outline the Adria-lonian subduction in the Tyrrhenian Sea and the deep-reaching lithospheric root in the Western Alps. Less deep lithospheric roots are seen in the Central Apennines. The lithosphere-asthenosphere properties delineate a differentiation between the northern and the southern sectors of the Adriatic Sea, likely attesting the fragmentation of Adria

Coexisting contraction-extension consistent with buoyancy of the crust and upper mantle in North-Central Italy

The juxtaposed contraction and extension observed in the crust of the Italian Apennines and elsewhere has, for a long time, attracted the attention of geoscientists and is a long-standing enigmatic feature. Several models, invoking mainly external forces, have been put forward to explain the close association of these two end-member deformation mechanisms clearly observed by geophysical and geological investigations. These models appeal to interactions along plate margins or at the base of the lithosphere such as back-arc extension or shear tractions from mantle flow or to subduction processes such as slab roll back, retreat or pull and detachment. We present here a revisited crust and upper mantle model that supports delamination processes beneath North-Central Italy and provides a new background for the genesis and age of the recent magmatism in Tuscany. Although external forces must have been important in the building up of the Apennines, we show that internal buoyancy forces solely can explain the coexisting regional contraction and extension

Structure of the lithosphere-asthenosphere and volcanism in the tyrrhenian sea and surroundings

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Coexisting contraction-extension consistent with buoyancy of the crust and upper mantle in North-Central Italy

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

The lithosphere-asthenosphere: Italy and surroundings

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal