Evolution of mantle-crust fluid systems

Mantle-crust fluid systems are associated with zones of decompression melting above hot spots. The place and duration of their development are different at the progressive and regressive stages of the related melting zone (asthenospheric lens or plume). Mass exchange and metasomatism in lithospheric rocks ( structure of metasomatic column), including the degree of granitification, are controlled by the structural pattern of permeable zones above the fluid systems. Strong metasomatic alteration of mantle rocks can change their density as much as to make the anomalous high and low densities in the temperature field different from the rho= f ( T, P) functions used in tomographic interpretations. Local melting of metasomatized lithospheric rocks above melting zones (plumes) appears to be quite common to the mantle-crust fluid systems.