Numerical Experiments on Archean Transmogrification and Craton Building

Transmogrification is a continent-shaping process in which thick sedimentary basins form on oceanic lithosphere, radioactively heat themselves and their underlying crust and mantle, and then partially melt to form ‘transmogrified continental crust’. Here we explore thermochemical models of crustal evolution in the Archean and Hadean by coupling 1-D thermal evolution models to a thermodynamic PerpleX model for the chemical changes that take place as (mostly) terrestrial and/or arc-derived sediments are buried and heated. We focus on exploring a Hadean evolution scenario in which plate tectonic processes started near the end of Earth’s accretion phase, consistent with a geochemically significant amount of early atmospheric Xe and Kr having been recycled by subduction into the mantle sources of modern mantle-derived basalts.

Preliminary results indicate that early Archean transmogrification can rapidly (<~50 Ma) induce a thick sediment pile to partially melt and differentiate. Transmogrification will also shape the thermal evolution of underlying cratonic mantle, and perhaps even trigger a lithospheric delamination event associated with renewed basaltic/komatiitic volcanism. We are currently exploring to what extent this mode of crustal and lithospheric evolution could lead to the formation of Archean-typifying TTG-Greenstone Belt assemblages.