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

European Geosciences Union General Assembly 22-27 April 2012, Vienna, Austria.-- 1 pageLocated between Italy, Corsica, Sardinia and Sicily the Tyrrhenian Sea is a Neogene back-arc basin formed by continental extension related to the southeastward rollback of the subducting Ionian oceanic plate. This basin is an ideal place to study the evolution of extension process. The basin structure displays different amount of extension along its length, from the low-extension episodes of continental rifting in the northern areas to break up and exhumation of the mantle in the deepest part of the basin. Here there also seems to be evidence of extension-associated volcanism. In order to study the nature of the crust and the 4D evolution of the Tyrrhenian basin, a survey to collect multichannel (MCS) and wide-angle seismic (WAS) data was carried out into the framework of the MEDOC project 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 both Ocean Bottom Hydrophones and Seismometers (OBH/S) and simultaneous land recordings in Corsica, Sardinia and Italy. In this work we present modeling results along two WAS lines that cross the central and deepest area of the basin. The models, which are obtained by joint refraction and reflection travel-time tomography, unveil the seismic structure of the crust and uppermost mantle and the geometry of the Moho boundary. The data selected for the inversion are arrival times of phases refracted through the crust and upper mantle (Pg and Pn phases), and those reflected at the Moho boundary (PmP phases). A statistical uncertainty analysis has been also performed to account 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 has allowed defining various different crustal domains. In the western side of the profiles, the models show a progressive transition between a 23 km-thick continental crust, and a thinned, and apparently magmatically-intruded crust 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-developed Moho boundary. In this area, the velocity model indicates that the basement is mainly made of exhumed upper mantle rocks such as those described in the ODP Leg 107 in 1990. Finally, in the central part of the basin where the exhumed mantle domain is larger we find three low-velocity anomalies attributed to the extension-related magmatismPeer Reviewe

Updating temperature and salinity mean values and trends in the Western Mediterranean: the RADMED project

Postprin

Rifting of the Tyrrhenian Basin, a complex interaction among faulting, magmatism and mantle exhumation

European Geosciences Union General Assembly 22-27 April 2012, Vienna, Austria.-- 1 pageThe Tyrrhenian basin has been created during the extension of continental lithosphere driven by the retreat of a Ionian slab across the mantle. The basin does not seem to be actively extending, but its preserved crustal structure provides information of the time evolution of the processes involved in rifting. The basin rifted from north to south, with rifting stopping after progressively larger stretching factor towards the south. The northern region stopped opening after a relatively low extension factor. Towards the south extension increased up to full crustal separation that produced mantle exhumation. The final structure displays two conjugate margins with asymmetric structures. Thus, the basin provides a natural laboratory to investigate a full rift system, that displays variable amounts of extension. We present observations from a two-ship seismic experiment that took place in spring 2010. The cruise took place on two legs. In the first leg, the Spanish R/V Sarmiento de Gamboa and the Italian R/V Urania collected five E-W trending wide-angle seismic (WAS) profiles across the entire basin using 17 Ocean Bottom Seismometers and 25 Ocean Bottom Hydrophones and a 4800 c.i. G-II gun array. The profiles were extended with land stations that recorded the marine shots. During a second leg the R/V Sarmiento de Gamboa collected 16 Multichannel Seismic Reflection (MCS) profiles using a 3.75 km-long streamer and a 3000 c.i. G-II gun array. MCS profiles were acquired coincident with the WAS profiles, and a number of additional lines concentrated in the central region of the basin where mantle exhumation took place. The seismic profiles were located to cover regions of the basin that displays different amount of extension, and the coincident wide-angle and MCS transects cross the entire basin to image the two conjugate margins. In this presentation we compare observations from different transects mapping the structures produced at different extension factors. A comparison of the different transects permits to trade space (different transects mapping different extension factors) for time (different transects provide an evolutionary snapshot of the extension process). Each transect provides the tectonic structure, the geometry of sedimentary deposits, and P-wave seismic velocity distribution. This information allows to interpret the mechanisms of deformation, infer the importance and potential role of magmatism in the rifting process, and estimate the region of mantle exhumation, currently inferred from one drill site. The analysis of the data provides insight in the process of formation of asymmetry structure conjugated marginsPeer Reviewe

Synthesis of exo‐Enamides from Protected Lactams Using a Modified Julia Olefination Reaction: Application to the Synthesis of Spiroaminal Fragments

International audienceA modified Julia olefination (Julia–Kocienski) reaction involving lactams has been developed, which gives the corresponding substituted exo-enamides in moderate to good yields. An application of this versatile transformation in the synthesis of spiroaminal fragments is also demonstrated

The Tyrrhenian Basin structure: continental rifting , seafloor spreading and mantle exhumation

8th workshop of the ILP-Task Force on Sedimentary Basin, 14-18 October 2013, MarseillePeer Reviewe

The structure of the Tyrrhenian from integration of multichannel seismic images, wide-angle seismic data, and gravity modeling

86° Congresso della Società Geologica Italiana, 18-20 Settembre 2012, Arcavacata di RendePeer Reviewe