Plutonism and the origin of metamorphic core complexes

The formation of metamorphic core complexes may be triggered by plutonic activity during episodes of continental extension. Pulses of ductile deformation have taken place during short-lived thermal events initiated by the heat input from intruded plutons, sills, or dikes. Such intrusions may be the underlying cause for differential uplift of the footwall during tectonic denudation of metamorphic core complexes. Heterogeneity of ⁴⁰ Ar/ ³⁹ Ar apparent ages can be explained by rapid cooling of deforming mylonites formed at shallow crustal levels in the thermal aureoles of intruded sills. -from Authors