GEOCHEMISTRY OF PETROGENESIS OF GRANITOID S OF THE MUYA COMPLEX (EASTSIBERIA)

The geological structure, mineralogy, and petrogeochemical peculiariti es of granitoids of the Muya gabbro-tonalite-plagiogranite complex in the eastern art of the Baikal-Muya ophiolite belt are considered. Acid ic plutonic rocks of the Muya complex belong to typical granitoids of the M-type and have isotope-geochemical characteristics close to the m antle ones. Formation of granitoids of the Muya complex proceeded unde r the conditions of developed volcanic are, whose most probable modern analog is the Aleutian Islands-Alaska system. It is shown that the ma in types of the complex rocks - tonalites, plagiogranites, and two-fel dspathic granites - formed as a result of the pulsation intrusion of m agma portions of different composition into the upper horizons of the crust. This magma is the product of the fractionation of a single tona lite melt formed as a result of the partial melting of the ensimatic b ase of the island are under isochemical conditions, which resulted fro m the conductive heating of host rocks by basalt magma.