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The Australian National University

Dating deformation and metamorphism

To understand the tectonic evolution of the Earth we need to know when events occur, and how fast they take place.

The 40 Ar/ 39 Ar system is unique in that it allows both geochronology and geospeedometry, as well as direct dating of fabrics, where the effect of different deformational events can be preserved in a single rock, or grain. Regional metamorphism as well as short-lived metamorphic events can be distinguished and dated using SHRIMP. Microstructural analysis with 40 Ar/ 39 Ar geochronology offers a powerful and complementary tool to determine the temporal evolution of mountain belts.

Understanding high-grade metamorphic processes is fundamental for the comprehension of the dynamics of plate tectonics and the differentiation of the Earth. The continental crust records extreme metamorphic conditions and extensive partial melting in various tectonic settings such as subduction, collision and continental break up.

Detailed knowledge of such high-grade metamorphic processes thus provides evidence for how continents work and how mineral resources form.

Updated: 16 December 2011/ Responsible Officer:  Director / Page Contact:  Webmaster