Granite magma formation, transport and emplacement in the Earth's crust

The origin of granites was once a question solely for petrologists and geoc hemists. But in recent years a consensus has emerged that recognizes the es sential role of deformation in the segregation, transport and emplacement o f silica-rich melts in the continental crust. Accepted petrological models are being questioned, either because they require unrealistic rheological b ehaviours of rocks and magmas, or because they do not satisfactorily explai n the available structural or geophysical data. Provided flow is continuous , mechanical considerations suggest that-far from being geologically sluggi sh-granite magmatism is a rapid, dynamic process operating at timescales of less than or equal to 100,000 years, irrespective of tectonic setting.