Tortonian-Pleistocenic oceanic features in the Southern Tyrrhenian Sea: magnetic inverse model of the Selli-Vavilov region |
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Authors: | L Cocchi F Caratori Tontini C Carmisciano M Marani |
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Institution: | (1) Istituto Nazionale di Geofisica e Vulcanologia, U.P. Geofisica e Tecnologie Marine, Via Pezzino Basso 2, 19025 Fezzano (SP), Italy;(2) Sezione di Geologia Marina, ISMAR-CNR, Via Gobetti 101, 40129 Bologna, Italy |
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Abstract: | We show the magnetic model of the Selli-Vavilov region. The Selli Line is known as the northwestern edge of the southern Tyrrhenian
Basin. The tectonic evolution of the Tyrrhenian Basin is dominated by a Tortonian-Quaternary extension through the eastward
movement of the Apennine subduction system. This migration has generated a diffuse stretching of the continental crust with
the emplacement of new oceanic material. This latter occurred in several localized zones where the eastward retreating of
the Ionian subduction system produced a strong depletion of the crust with formation of basins and correlated spreading. Nowadays
the presence of oceanic crust is confirmed through direct drilling investigation but a complete mapping of the oceanic crustal
distribution is still lacking. The Selli-Vavilov region shows a differentiated crustal setting where seamount structures,
the oceanic basement portions and continental crust blocks are superimposed. To this aim, a 2D inversion of the magnetic data
of this region was conducted to define buried structures. The magnetic susceptibility pattern was computed by solving the
least squares problem of the misfit between the predicted and real data for separated wavebands. This method produced two
2D models of the high and low frequency fields of the Selli-Vavilov region. The two apparent susceptibility maps provide different
information for distinct ranges of depth. The results of the inversions were also combined with seismic data of the Selli
region highlighting the position of the highly magnetized buried bodies. The results confirm a role for the Selli Line as
a deep crustal boundary dividing the Sardinian passive domain from the easternmost active region where different oceanic structures
are located. The Selli Line has worked as a detachment fault system which has moved eastward. Finally, the Selli-Vavilov region
may be interpreted as a tectonic result due to a passive asymmetrical rift occurred between the Tortonian and Pliocene. |
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Keywords: | Geomagnetism Tectonics Geodynamics Inversion Volcanic structure Oceanic crust |
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