ABSTRACT
Four main stages have been distinguished in the Earth’s development: lunar, nuclear, cratonic and continental–oceanic, each characterized by its own style of igneous activity and its relationship with geodynamics. Some researchers consider the boundaries between the first three stages as being caused by significant impact events 3.5, 3.0 and 2.7 Ga ago, although the available geological and petrological data rather tend to favour internal reasons for this type of evolution. The two most popular models for the Earth’s formation are: the homogeneousand heterogeneous. The low volatile content of lunar rocks can be inferred from the widespread development of the iron-troilite assemblage and the almost complete absence of hydrated minerals and ferric iron. The early Archean magnesian-suite magmatism from the highlands of the Moon, which intruded the primary anorthositic crust, is represented by high-Al volcanics and intrusive rocks.
