Current Research in Earth, Environmental and Planetary Sciences: Georgia Peterson, The University of British Columbia
Volcanism and Effects on Magnetic Field and Atmosphere Evolution of the Terrestrial Planets
Mercury, the closest planet to the Sun and the smallest planet in our solar system is in many ways enigmatic. MESSENGER, the first spacecraft to orbit Mercury, revealed an early evolution marked by widespread volcanism, contractional tectonics, and a magnetic field. Current thermal evolution models for Mercury attempt to match the total amount of contraction over time inferred from images, but they cannot sustain a magnetic field at ~4.0 Ga. A critical omission of previous models is that they do not include the key constraint provided by extensive volcanic resurfacing that formed Mercury’s thick basaltic crust. In this talk, I revisit the thermal history of Mercury. In particular, I incorporate mantle melting and effusive volcanism (volcanic cooling) and show that it drives a period of strong mantle cooling that both favors an ancient dynamo and explains Mercury’s basaltic crust.
In discussing future work, I will address the potential importance of volcanic cooling in reconciling the strongly contrasting dynamo and atmospheric evolutions of early Mars, Venus and Earth. Widespread mantle melting and related volcanism resurfaced these planets and produced global crusts on Mars by ~4.0 Ga and on Venus relatively recently (~0.5 Ga). On Earth there is evidence of an increased basaltic crustal production phase early in the planet’s history. In exploring the mechanics and implications of volcanic cooling I will also discuss how this heat transfer process is modulated by the extent to which melts are stored in the lithosphere or erupted at the surface. Crustal production and dynamo constraints on this “eruption efficiency” also bound processes governing volcanic outgassing, atmospheric production and evolution. A future research goal is to develop a self-consistent modelling framework that will enable rigorous investigations of the coupled magnetic, volcanic and ultimately climatic evolutions of each of the inner solar system planets.