Gravity redistribution of orogenic lower crust – Laterally Forced Overturns
The HP granulites are spatially, temporally and genetically related to ultrapotassic magmas which testify for complex interactions between lower crust and upper mantle in hot orogens. Heating of relaminated radiogenic triggers Rayleigh-Taylor instability and melting of underlying metasomatized mantle. The gravity redistribution of granulitic lower crust is a major problem of many large hot orogens all over the world starting from Archean to recent. The causes of gravity overturns, mechanisms, P-T-D-t records of vertical material and heat transfers are hotly debated. Laterally Forced Overturning is a main process responsible for exhumation of granulitic lower crust in the Bohemian Massif which becomes a world class field laboratory where details of this spectacular mechanism can be studied.