Multidisciplinary seismological and gravimetric investigations in the Western Alps: a new view on the Ivrea geophysical body

Séminaire de Matteo Scarponi, post-doctorant à l’Université de Lyon

Résumé:
The Western Alps (Europe), and the Ivrea-Verbano Zone in particular
(IVZ, Piedmont, Italy), constitute one of the best open-air natural
laboratories for the study of the continental crust, spanning from local
(sub-km) to regional (100s of km) spatial scales. The IVZ exposes at the
surface an almost unique, and nearly complete, cross-section of the
continental crust, ranging from upper-crustal to lower-crustal (and
mantle) composition rocks. Below the surface, both gravimetric and
seismological investigations reveal the existence of a dense, fast
structure. This outstanding crustal anomaly extends along the whole arc
of the Western Alps, and it is known as the Ivrea Geophysical body
(IGB). Important scientific questions concern the IGB and its
relationship to the surface geological observations: what is the link
between the anomalous IGB structure and the surface lower-crustal
outcrops? Furthermore, how is the IGB structure and composition changing
at depth? New gravimetric and seismic data provide the opportunity for
further advances on this topic, via Bouguer gravity, seismic receiver
functions and ambient noise analysis and modeling.