The crust of Venus: Theoretical models of chemical and mineral composition

Abstract

Physico‐chemical modeling of the atmospheric‐lithospheric interaction on Venus is presented. The thermodynamic assessment is carried out in terms of Venera 11 and 12 and Pioneer Venus measurements and the dynamic atmospheric structure. The subcloud atmosphere is interpreted to be a zone of nonequilibrium chemical conditions while the near‐surface layer is presumed to be an equilibrium zone due to catalytic effects and low wind velocities. The mineral assemblages of the ‘weathering crust’ are calculated. The pyrite‐anhydrite‐magnetite assemblage is suggested as the buffering system resulting in reducing conditions (P02≈ 10−21 atm). The existence of hydration is problematic and is thermodynamically conceivable only for the sulfur enrichment of primary rocks (about 2 wt. %). The carbonate minerals are suggested to be unstable.

Derivation of primary magmas and melting of crustal materials on Venus: Some preliminary petrogenetic considerations

“…1987) and atmosphere (Donahue and Pollock, 1983), and atmosphere-surface interactions (Barsukov et al, 1982;Nozette and Lewis, 1982) have become more well known. The emerging picture of geologic and geophysical processes operating to shape and modify the surface and interior provides a basis for the discussion of petrogenesis and petrogenetic processes on Venus, following some early considerations (e.g., Warner, 1983).…”

Venus atmospheric and surface studies from VIRTIS on Venus Express

“…Most of it appears to consist of basalt, but the primary rocks are poorly classified. 7,73 The volcanic landforms are consistent with low-viscosity eruptions, which are characteristic of mafic rocks like basalt. 33 The Magellan radar data indicate a global resurfacing by a violent volcanism in the younger history of the planet about 500 -700 million years.…”

Coevolution of Life and Earth

“…Despite the desertlike images of the Moon (Taylor, 1982), Venus (Barsukov et al, 1982), and Mars (Squyres et al, 2004), no pedogenic carbonate has yet been detected beyond Earth. Spectroscopic detection of carbonate minerals in Martian dust (Bandfield et al, 2003) may have the same source as carbonate in Martian meteorites and carbonaceous chondrites, which are vein-filling crystalline carbonate, some of it formed at high temperatures (McSween, 1997).…”

“…Soil formation on the basaltic parent material may be a rapid process akin to pottery glazing ( Figure 1), in which salts are melted to obscure the hard edges of rocks and sediments (Barsukov et al, 1982).…”