Rate of magmatism as a function of stretching rate and mantle potential temperature during and after continental rifting: insights from thermomechanical numerical models

Magmatism along divergent continental margins is mainly controlled by adiabatic decompression induced by the divergent motion of the continental lithosphere and the consequent upwelling of the asthenospheric mantle. Additionally, the mantle potential temperature, fertility, and volatile content also affect the rate of magmatism. Due to the complexity of the geodynamic evolution of the margin with the concomitant magmatism, the use of numerical models represents an appropriate approach. To quantify the rate of magmatism through time, since the onset of lithospheric stretching, during and after the rifting phases, we performed a series of numerical simulations considering different stretching rates, rheological structures for the lithosphere and mantle potential temperature.   To perform the numerical simulations, we used the thermomechanical numerical code Mandyoc, considering recent implementations of calculation of melt fractions, incorporation of latent heat in the energy conservation equation, and influence of melt depletion on density and viscosity.  The volume of magmatism obtained in the numerical simulations is  compared with different segments of the Brazilian margin with variable degree of magmatism,  based on interpreted seismic data published for these portions of the continental margin.