de Franco, R.

Grevemeyer, Ingo

Guzman, M.

Prada, M.

Ranero, César R.

Sallares, V.

Zitellini, N.

English

OceanRep

Geophysical Research AbstractsVol. 14, EGU2012-10323, 2012EGU General Assembly 2012© Author(s) 2012Deep structure of the Tyrrhenian basin from 2-D joint refraction andreflection travel-time tomography of wide angle seismic dataM. Prada (1), V. Sallares (2), C.R. Ranero (3), M. Guzman (4), N. Zitellini (5), I. Grevemeyer (6), R. de Franco(7), and MEDOC Cruise Party ()(1) Unidada de Tecnología Marina, B-CSI, CSIC. Barcelona, Spain (mprada@cmima.csic.es), (2) Unidada de TecnologíaMarina, B-CSI, CSIC. Barcelona, Spain, (3) Instituto de Ciencas del Mar, B-CSI, ICREA at CSIC. Barcelona, Spain, (4)Instituto de Ciencas del Mar, B-CSI, CSIC. Barcelona, Spain, (5) ISMAR-CNR. Bologna, Italy, (6) IFM-GEOMAR. Kiel,Germany, (7) IDPA. CNR, Milan, ItalyLocated between Italy, Corsica, Sardinia and Sicily the Tyrrhenian Sea is a Neogene back-arc basin formed bycontinental extension related to the southeastward rollback of the subducting Ionian oceanic plate. This basinis an ideal place to study the evolution of extension process. The basin structure displays different amount ofextension along its length, from the low-extension episodes of continental rifting in the northern areas to breakup and exhumation of the mantle in the deepest part of the basin. Here there also seems to be evidence ofextension-associated volcanism.In order to study the nature of the crust and the 4D evolution of the Tyrrhenian basin, a survey to collectmultichannel (MCS) and wide-angle seismic (WAS) data was carried out into the framework of the MEDOCproject in 2010 with the coordination of 2 research vessels, the R/V Sarmiento de Gamboa and the R/V Urania.During the experiment a total of 17 MCS lines and 5 WAS lines were acquired, with 125 deployments of bothOcean Bottom Hydrophones and Seismometers (OBH/S) and simultaneous land recordings in Corsica, Sardiniaand Italy.In this work we present modeling results along two WAS lines that cross the central and deepest area ofthe basin. The models, which are obtained by joint refraction and reflection travel-time tomography, unveil theseismic structure of the crust and uppermost mantle and the geometry of the Moho boundary. The data selectedfor the inversion are arrival times of phases refracted through the crust and upper mantle (Pg and Pn phases), andthose reflected at the Moho boundary (PmP phases). A statistical uncertainty analysis has been also performed toaccount for the inverted model parameters uncertainty (velocity values and Moho geometry).The seismic structure of both models reveals a significant lateral variation of the velocity gradient that hasallowed defining various different crustal domains. In the western side of the profiles, the models show a pro-gressive transition between a 23 km-thick continental crust, and a thinned, and apparently magmatically-intrudedcrust with a well-defined Moho boundary. Thinning is more pronounced in the central, deepest part of the basin,where the abrupt thinning coincides with the absence of PmP reflections and, in turn, with that of a well-developedMoho boundary. In this area, the velocity model indicates that the basement is mainly made of exhumed uppermantle rocks such as those described in the ODP Leg 107 in 1990. Finally, in the central part of the basin wherethe exhumed mantle domain is larger we find three low-velocity anomalies attributed to the extension-relatedmagmatism.

Deep structure of the Tyrrhenian basin from 2-D joint refraction and reflection travel-time tomography of wide angle seismic data

Deep structure of the Tyrrhenian basin from 2-D joint refraction and reflection travel-time tomography of wide angle seismic data

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