Mitchell McMillan

Continental tectonics and geodynamics

Earth’s largest orogens are excellent natural laboratories, because they offer our most complete record of geodynamic processes, from active collision (Himalaya—Tibet) and Cordilleran shortening (Andes) to post-orogenic collapse (Western US). My research addresses two fundamental questions: (1) What are the ultimate drivers of continental deformation and orogenesis? and (2) How is topography modified by both tectonics and climate over geologic time?

In addition to the well-known forces that build up and tear down mountains, I’m also interested in more poorly understood (in some cases overlooked) processes that may nevertheless control major aspects of mountain building and topography. These include wind erosion, eclogitization (the formation of a dense crustal root), and lithospheric foundering (the removal of the root).

To investigate these phenomena, I utilize a combination of numerical modelling and field work, integrating data from low-temperature thermochronology, geochronology, and geologic mapping with cutting-edge numerical simulations of geodynamic and thermodynamic processes. The most comprehensive synthesis of this research is currently my Ph.D. thesis, which can be accessed here.

The following articles describe some of these topics in more detail.

Lithospheric foundering
A deep-seated geodynamic process that may affect the evolution of mountain belts.
geodynamics, orogenesis, numerical modelling
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Thermodynamics of lower crustal buoyancy.
thermodynamics, fluid-mediated reactions, crustal metamorphism
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Wind erosion
Hyperarid regions, such as orogenic plateaus, are mainly eroded by wind, rather than rivers or glaciers
eolian processes, climate-tectonics interactions
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Streambank erosion (M.Sc. thesis)
Applying models to predict streambank erosion rate in the Gulf Coastal plain.
fluvial geomorphology, numerical modelling, environmental geology
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