Fred Gaidies, Department of Earth Sciences

Some of the most elemental properties of our planet’s crust include its behaviour during plastic deformation, the way it transmits seismic waves, or the rate with which thermal anomalies form and dissipate in response to tectonic processes. I will use this talk to introduce you to modern metamorphic petrology – that branch of geology that is concerned with the mineralogical and microstructural changes that occur when rocks of our planet’s crust get buried and heated inside the Earth. Unmetamorphosed rocks like granite or mudstone turn into metamorphic rocks when involved in the collision of continents. One of the most spectacular examples of metamorphism that is currently ongoing can be studied in the Himalayas where India collides with Asia. Rocks get heated and deformed during burial and recrystallize into metamorphic rocks such as gneisses or schists forming the roots of the mountain chain. Erosion of the mountains exposes metamorphic rocks at the surface where we can study their mineral content and microstructure to infer the tectonic processes responsible for their formation. Considering that tectonic processes have been documented over most of our planet’s history, the correct deciphering of the mineralogical and microstructural information contained in metamorphic rocks helps us to understand how Earth’s crust has behaved since its birth.

Wednesday, February 8, 2017 in
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