Global warming of the mantle beneath continents back to the Archaean

Abstract

Throughout its history, the Earth has experienced global magmatic events that correlate with the formationof supercontinents. This suggests that the distribution of continents at the Earth's surface is fundamental inregulating mantle temperature. Nevertheless, most large igneous provinces (LIPs) are explained in terms ofthe interaction of a hot plume with the lithosphere, even though some do not show evidence for such amechanism. The aggregation of continents impacts on the temperature and flow of the underlying mantlethrough thermal insulation and enlargement of the convection wavelength. Both processes tend to increasethe temperature below the continental lithosphere, eventually triggering melting events without theinvolvement of hot plumes. This model, called mantle global warming, has been tested using 3D numericalsimulations of mantle convection [Coltice, N., Phillips, B.R., Bertrand, H., Ricard, Y., Rey, P. (2007) Globalwarming of the mantle at the origin of flood basalts over supercontinents. Geology 35, 391–394.]. Here, weapply this model to several continental flood basalts (CFBs) ranging in age from the Mesozoic to theArchaean. Our numerical simulations show that the mantle global warming model could account for thepeculiarities of magmatic provinces that developed during the formation of Pangea and Rodinia, as well asputative Archaean supercontinents such as Kenorland and Zimvaalbara.