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Abstract

A summary of the latest data on isotope geochemistry of the lunar rocks shows that their silicon, oxygen and refractory metals isotopic composition are no different from terrestrial one, indicating a single source of origin of both Earth's and Moon's substances. At the same time, the isotopic signature of the volatiles along with rubidium, zinc, gallium, potassium, iron in lunar rocks is fractionated considerably, showing heavy isotope enrichment compared to Earth's ones. Kinetic isotope effect, underlying this phenomenon, occurs during the process of lava degassing when volatiles emits from the magma surface to the vacuum of space. Thus, conditions of the crystallization of lunar rocks deviate significantly from those of Earth. We consider the formation of the Moon following Marakushev's fission theory. In the view of the theory, the Moon has been spun from proto-Earth, while a necessary impulse moment reached due to a proto-Earth's initial fluid veneer.