Thermal and chemical evolution of the oceanic lithosphere

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The cooling of Earth's interior controls many planetary scale processes such as plate motions and the geodynamo. The plate tectonic paradigm involves the cooling of Earth's core and mantle largely through the subduction of cold plates. Further heat loss occurs via conduction through the plates. The relative importance of these processes depends principally on the cooling of the oceanic lithosphere between its creation at mid-ocean ridges and demise in subduction zones. However, the cooling and chemical evolution of the oceanic lithosphere are poorly understood. This is largely because the primary data used to constrain this, seafloor heat flow and bathymetry, cannot distinguish between existing models. I propose to use petrological and geochemical studies of the oceanic lithosphere to better understand the thermal and chemical evolution of the oceanic lithosphere. Studies of mantle xenoliths will constrain P-T-t paths in the deep portions of oceanic plates. Quantitative models of low-temperature hydrothermal alteration of the upper oceanic crust will help to constrain fluid fluxes in the off-axis. These data, combined with existing seafloor heat flow and bathymetry data, will be integrated into a model of the thermo-chemical evolution of oceanic plates and thus allow new insights into the thermal evolution of our dynamic planet.