Magma transport through tectonic plates: decoding messages from Earth's deep interior

One of the most important processes in the evolution of rocky planets is partial melting. It is the key to the layered structure of the planetary interior, including formation of continents on Earth (and possibly on rocky extrasolar planets too). Continents comprise some of the most buoyant materials found at Earth’s surface and, once formed, they stay at the surface for billions of years. Interestingly, melting and magma transport are also implicated in plate tectonics—the destruction/reshaping of continents—yet we lack a quantitative understanding of these linkages. For example, we do not know how much magma can be transported through a tectonic plate, and for how long, before it completely weakens and destabilizes it.

I present some simple ways in which physicists can help decode clues from the chemistry of magma and from the magma transport process itself. Using a simple set of coupled differential equations to represent the transport process, I argue that there may be very special circumstances required to actually heat, weaken, and destabilize a continental plate by flushing it through with molten material. I will end by speculating on some examples from Earth history where such destabilization may have occurred, such as the break up of supercontinents. Most importantly, my talk will outline some key problems that remain unanswered and how physicists can help model and interpret noisy Earth science data.