Irreversible Evolution of the Terrestrial Planets according to Geological and Petrological Data

How the terrestrial planetary bodies were developed? We discuss these problems on examples of the Earth and the Moon, which evolution studied the best. According to modern views, after accretion of the bodies, magma oceans of some hundreds km deep appeared on their surface. According to Jeffries (1929), solidification of large molted bodies, because of the difference between adiabatic gradient in silicate melts (0.3°C/km) and gradient of their melting points (3°C/km), could be going only upwards, from the bottom to the surface. As a result, a powerful crystallizing differentiation of the oceans' magmas led to accumulation of the most low-melting components on their surfaces. Due to different oceans deep, the primordial crusts on these bodies were rather different: sialic on the Earth and basic on the Moon. Geological evolution of the Earth began ~4 Ga ago from appearance of granite-greenstone terranes (GGT) and divided them granulite belts. Magmatism of high-Mg komatiite-basaltic series was located in greenstone belts, which formed irregular network within GGTs. They were formed above mantle superplumes of the first generation, composed by depleted (due to directed solidification of the magma ocean) ultramafic material; granulite belts were formed on places of descending mantle flows. The situation could be described in terms of plume- tectonics. By the 2.7-2.5 Ga the Earth's crust became cratonized and magmas of siliceous high-Mg series (SHMS) began predominate. Origin of the SHMS was linked with large-scale assimilation of lower crustal material by high-temperature mantle-derived magmas. Cardinal change of tectonomagmatic activity occurred 2.3-2.0 Ga with appearance in global scale of geochemical-enriched Fe-Ti picrites and basalts, typical for Phanerozoic within-plate magmatism and linked with mantle plumes of the second generation, which ascended from the liquid core-mantle boundary (CMB). It was followed by plate tectonic appearance ~2 Ga and such tectonic regime has existed till now. From this particular time, ancient Earth's continental crust began to involved in subduction processes and has replaced by secondary oceanic crust which forms about 70% of the present-day crust. We suggest that such situation could be possible only in case when (1) accretion of the Earth was heterogeneous, and (2) it's warming occurred downwards, from surface to core. It could be a result of moving inwards a wave of deformations, accompanied by emission of heat. Appearance of such wave could be linked with gradual compaction of material which led to acceleration of the Earth's rotation around axis. At the first stage the wave went through depleted mantle and led to appearance of mantle superplumes of the first generation. At the second stage it reached and melted iron core. It led to appearance of mantle superplumes of the second generation (thermochemical), enriched in fluids, Fe, Ti, and incompatible elements. Material of such superplumes reached more shallow levels, which led to active interactions of their extended heads with solid lithosphere and caused changing in tectonic activity. Terrestrial planets were developed at the same, but shortened scenario. At the Moon the earliest magmatism of highlands were close to terrestrial SHMS and at the boundary 3.9-3.8 Ga ago was changed by maria magmatism, close in composition to MORB and OIB. By analogy with the Earth, we suggest that maria magmatism was linked with ascending of thermochemical superplumes, generated at the lunar CMB, when it's liquid iron core was yet existed. Ancient planums on Mars and tesseras on Venus among vast planides, composed by basaltic flows, can also evidence about two stages of their development.