Some New Data on the Genesis of Granitic Pegmatites

The correlation between the type of mineralization in granitic pegmatites and the depth of their formation is supported with new data. The fluid pressure in pegmatites is 2-3 times greater than that of the calculated lithostatic pressure due to the over-pressure of volatiles in the closed pegmatite system. Experimental work shows that during cooling the pegmatite melt saturated with volatile components divides into two or three fluids. Such a 'liquation' provides an explanation for many of the complex structures and peculiarities of the mineral composition obsei ved in pegmatites.

In many regions heterogeneous pegmatites (primarily magmatic or metamorphic) may converge through the processes of albitization and muscovitization. A specific group of post-magmatic pegmatite-like bodies can be formed as well.