Eclogitization

Thickening of continental crust can cause high-pressure metamorphic reactions that essentially break down plagioclase and orthopyroxene and produce garnet and clinopyroxene, forming eclogite. The primary result of eclogitization reactions is a density increase, reducing the buoyancy of the affected part of the crust. The lower crust can possibly even become negatively buoyant with respect to underlying mantle, and if it is weak enough, can founder gravitationally over 10-Myr timescales. Crustal foundering can affect important geological processes such as mountain building and sedimentary basin development. But the tectonic conditions that lead to eclogitization and foundering of the lower crust over relevant timescales are not currently well understood, partly because the coupled thermodynamic-geodynamic system is difficult to model.

A major part of my current research consists of modelling how this process operates using thermodynamic and geodynamic simulations. The goal of this research is to understand how and where foundering may have occurred on Earth, and then to better constrain the predicted consequences in the upper crust and geologic record.