Volcanism as a new constraint on the rheology of continents

Our knowledge of lithospheric rheology comes mostly from laboratory data using small-scale samples that are extrapolated to crustal and lithospheric scales, which requires careful analysis of the differences in boundary conditions. In the search for constraints on large-scale continental rheology, one useful observation has been neglected. That is the occurrence of volcanism genetically related to faulting activity, which can be used to obtain information about the rheology of the continents. The volcanism can be explained by a “Process zone heating” mechanism that occurs at fault system complexities. The rate of heating directly depends on the rheology, and we explore which conditions produce sufficient heat to melt independently the crust and the mantle of the continental lithosphere as required by the observations. By comparing the source depth given by modelling with the geochemical and petrological features of the volcanic products, we are able to discuss the strength profile required for the genesis of the magmas. A shift appears between the power flow law parameters obtained in the laboratory and the ones that are required for melting to occur. We describe and model here instances of volcanism along the North Anatolian Fault, Turkey, but the scope can be broadened to other cases.