Tectonic escape of Sicily Microplate in the context of Africa-Europe collision

<p>Sicily is in the centre of an area where complex geodynamic processes work together, these are: the Tyrrhenian-Apennine System evolution, the African-Ionian slab subduction and Africa-Europe collision.</p><p>During the last 5 Ma it was involved in a process of escape towards east-southeast: while on one side Africa acted as an intender pushing toward north, on the other side the fragmentation and retreat of the African-Ionian slab created space to the east.</p><p>The aim of this study is to reconstruct the kinematic evolution of Sicily, here considered as an independent plate starting from 5 Ma ago, and its role in the context of the Tyrrhenian-Apennine system.</p><p>The plates and microplate involved in the evolution are Europe, Africa and Calabria. The boundaries between these and Sicily are the margin of the Sicily microplate and are lithospheric structures known from the literature and identifiable from high resolution bathymetric maps, seismic sections, geodetic data, focal mechanism of recent earthquakes, gravimetric maps, lithosphere thickness maps and so on.</p><p>Briefly the margin between Sicily and Europe is along the Elimi chain, a E-W trending morpho-structure with transpressive kinematics, the margin with Calabria microplate is along the right-lateral Taormina line and the margin with Africa is expressed along the Malta Escarpment, south of Etna Mount, with transpressive kinematics and along the Sicily Channel, where a series of troughs (Pantelleria, Linosa and Malta) were interpreted in literature as pull-apart basins related to a dextral trascurrent zone.</p><p>The Euler pole of rotation between Sicily and Africa was found starting from the structures in the Sicily Channel and using the GPlates software, then we were able to find also Sicily-Europe and Sicily-Calabria poles and the respective velocity vectors and to compare these with the geological data and better refine the model.</p>

Eastward Tectonic Escape of Sicily Microplate: preliminary results

<p>The complex processes affecting the Tyrrhenian-Apennine System are inevitably reflected in Sicily, here considered as an independent plate starting from 5 Ma and located between Europe and Africa plates and Calabria microplate.</p><p>In particular the retreat of the Adriatic-Ionian slab and its fragmentation involve Sicily in a process of escape towards east-southeast due to the space that the slab is creating. At the same time Africa acts as an intender during its convergence with the European plate.</p><p>We show here the preliminary results of a study that aims to reconstruct the kinematic evolution of Sicily and its role in the framework of the Tyrrhenian-Apennine System.</p><p>First of all we found the margins of the plate, searching for lithospheric structures that can be considered as plate boundaries, using different types of data (high resolution bathymetric maps, seismic sections, geodetic data, focal mechanism of recent earthquakes, gravimetric maps, lithosphere thickness maps…) together with the literature.</p><p>The margins are:</p><p>-The Sicily Channel, characterized by a series of pull-apart basins related to a dextral trascurrent zone (Sicily-Africa margin);</p><p>-The Malta escarpment and the Taormina Line characterized by transpression (Sicily-Calabria margin);</p><p>-The Drepano-Ustica seamount also characterized by transpression (Sicily Europe margin).</p><p> </p><p>Starting from the structures in the Sicily Channel, we found the Euler pole of rotation between Sicily and Africa using the GPlates software. Thanks to the software we were able to find also Sicily-Europe and Sicily-Calabria poles and the velocity vectors.</p><p>Finally, we compared the Euler poles and the velocity vectors with the geological data, trying the best fit of the two and better refine the model.</p><p> </p><p><strong>Key Words</strong>: Sicily microplate, Sicily Channel, Malta Escarpment, Tyrrhenian-Apennine System.</p>

Conductive anomalies related to the Mérida Andes derived from the 3D inversion of a magnetotelluric profile

<div><span>Abstract</span> <div>The geodynamic settings of north-western Venezuela are conditioned by the expulsion of the North Andean Block (NAB), and the deformational structures related to the Caribbean – South America plate interactions. The most prominent feature is the 100 km wide Mérida Andes (MA) that reach from the Colombian border to the Caribbean coast over more than 500 km. We present the analysis of a magnetotelluric (MT) profile acquired at 72 broadband sites along a 240 km long profile with station spacing between 3 and 5 km across the central part of the MA, including the sedimentary Maracaibo (MB) and Barinas-Apure (BAB) basins. Phase Tensors (PT) are consistent with 1D/2D dimensionality above the MB and the BAB, however, stations above the MA show a clear 3D dimensionality, with the induction vectors indicating the presence of off-profile structures. Following the dimensionality analysis, 3D inversions of the entire dataset were performed, employing the finite differences code ModEM. The results are in agreement with prominent geological structures, and are particularly effective in modelling the depth extensions of major fault systems. A conductive structure east from the profile at mid crustal levels seems to correlate with the tectonic escape of the Trujillo block, which is part of the NAB.</div> </div>