Precambrian intraplate magmatism: high temperature low pressure granulites.

Starting from the hypothesis that the lower continental crust is dominated by granulites, some essential features of granulites are recalled. Two general P-T-t paths are possible, clockwise and anticlockwise, of which the former is more common for high pressure granulites, the latter for low pressure granulites. For high temperature, low pressure granulites, granulite metamorphism appears to be a discrete event, caused by a sudden temperature increase in a more or less thickened crust. The complex granulite chemistry, characterised by the possible mobility of some elements (LILE, Ti), as well as the P-T-t evolution, are explained by two complementary mechanisms operating simultaneously in different domains and at a variable scale: fluid-absent melting and fluid-assisted metamorphism (high salinity aqueous fluid and high density CO