The Structure of the Continent‐Ocean Transition in the Gulf of Lions From Joint Refraction and Reflection Travel‐Time Tomography

The Gulf of Lions—Ligurian basin, in the Western Mediterranean, opened from end Oligocene to Miocene as a back-arc basin driven by rollback Ionian slab. Geophysical surveys across margin have explored crustal structure and continent-ocean transition (COT), but its location petrological nature is still matter debate. Here, we apply joint refraction reflection travel-time tomography that combines travel-times multichannel seismic wide-angle data provide improved constraints on P-wave velocity sediment cover geometry top basement with respect previous studies. Similar earlier works, model shows three domains, their internal differ. We identify ∼100 km-wide domain oceanic crust an anomalously high upper possibly caused porosity-canceling processes triggered 7–8 km thick overlying cover. vertical thickness are similar back-arcs Pacific Mediterranean. In contrast interpretations, propose this confined between two domains ultra-thin (4–5 km-thick) continental crust, COT <10 wide either side crust.