Continental Subduction in the Western Alps: Facts and Theories

Once that continental subduction was largely accepted (by the end of the 1980’s), it immediately opened a range of major questions, amongst which the most important are summarized below.

• Is continental subduction always succeeding oceanic subduction, the buoyant continental crust being dragged down by the subducting slab of oceanic lithosphere?
• Which parts of the continental crust are subducted? Is it the entire palaeomargin, or just parts of it, for example extensional allochthons? What is the role of the inherited structures associated with the rifting history of the palaeomargin?
• What is the petrological record of burial and exhumation in the continental crust? Dehydration takes place during a first orogenic cycle. How can we develop (U)HP parageneses in continental (polycyclic) basement? What role plays the fluid phase in the preservation of the pre-Alpine and early-Alpine assemblages?
• What is the age of the HP/UHP metamorphism? What are the rates of exhumation?

This talk will answer to some of these questions in the specific case of the European Alpine belt.

Short bio: Paola Manzotti is Associate Professor at Stockholm University (Sweden). After completing her PhD at the University of Bern (Switzerland) in 2012, she worked at the University of Rennes (France) for three years, then she was awarded a Swiss NSF Ambizione Fellowship at the University of Lausanne (Switzerland) for three years. Her research focuses on the mechanisms of mountain building and, especially, on the rock record of burial and exhumation cycles. She combines fieldwork, metamorphic petrology, and geochronology in order to decipher the complex evolution of subducted continental crust.