Basaltic Volcanism on the Terrestrial Planets / Базальтовый вулканизм на планетах земной группы

The theme of this book is the study of basaltic volcanism as a stage in planetary evolution: to use the eruption of lava from the interior of a planet as evidence of the thermal and chemical processes of the planet. All lavas extruded on a planet’s surface can provide information about events in the interior. From a petrologic point of view, however, it is the more primitive lavas, which rise to the surface of a planet with minimal changes, that can provide the most information about the interior. In general, these more primitive lavas are basalts and so in Chapter 1 our sampling has concentrated on basaltic rocks.
Basalts are dark-colored, relatively fine grained volcanic rocks composed mostly of plagioclase and pyroxene, with lesser amounts of iron oxides and, in many cases, olivine. Chemically, basalts are characterized by Fc, Ca and Mg contents commonly in the range 5-15 wt.% oxide and by Si02 contents generally in the range 38-53 wt.%. This is a very general working definition because, for example, many lunar mare basalts and meteoritic basalts have FeO contents greater than 20 wt.%. <...>