12 Facts About Continental crust

Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves.

Continental crust is less dense than oceanic crust, whose density is about 2.

All continental crust is ultimately derived from mantle-derived melts through fractional differentiation of basaltic melt and the assimilation (remelting) of pre-existing continental crust.

The relative contributions of these two processes in creating continental crust are debated, but fractional differentiation is thought to play the dominant role.

Proponents of a steady-state hypothesis argue that the total volume of continental crust has remained more or less the same after early rapid planetary differentiation of Earth and that presently found age distribution is just the result of the processes leading to the formation of cratons.

The crust is thickened by the compressive forces related to subduction or continental collision.

The thinnest continental crust is found in rift zones, where the crust is thinned by detachment faulting and eventually severed, replaced by oceanic crust.

High temperatures and pressures at depth, often combined with a long history of complex distortion, cause much of the lower continental crust to be metamorphic – the main exception to this being recent igneous intrusions.

Continental crust is produced and destroyed mostly by plate tectonic processes, especially at convergent plate boundaries.

Continental crust is lost through erosion and sediment subduction, tectonic erosion of forearcs, delamination, and deep subduction of continental crust in collision zones.

Many theories of crustal growth are controversial, including rates of crustal growth and recycling, whether the lower crust is recycled differently from the upper crust, and over how much of Earth history plate tectonics has operated and so could be the dominant mode of continental crust formation and destruction.

The growth of continental crust appears to have occurred in spurts of increased activity corresponding to five episodes of increased production through geologic time.