CONCENTRATIONS OF H2O AND CO2 IN MAGMATIC MELTS, THE RESULTS OF STUDYOF INCLUSIONS IN MINERALS

Data have been summarized on concentrations of H2O and CO2 in magmatic silicate melts. These concentrations have been measured in homogenous melt inclusions in minerals and quenched volcanic glasses from the oc eanic bottom. Concentrations of petrogenic elements and H2O have been given in about 50 papers, 249 determinations of CO2 been given in 16 p apers. Average contents of H2O and CO2 equal to 0.831 and 0.047 wt% re spectively for magmas of basic composition (SiO2 < 53 wt%), whereas fo r intermediate magmas (SiO2 = 53 to 64 wt%)-2.271 and 0.163 wt% and fo r acid magmas (SiO2 > 64 wt%) - 3.292 and 0.017 wt% respectively. The ratio H2O/CO2 equals to 17.7 for basic and increases remarcably (up to 194) for acid magmas. Bearing in mind different abundances of these t ypes of magma in continents oceans, average contents of H2O and CO2 in magmas equal to 1.555 and 0.083 wt% respectively for the whole contin ental block (H2O/CO2 = 18.7). Average contents of H2O and CO2 in magma s equal to 1.001 and 0,056 wt% respectively for continents, continenta l margins and oceanic bottom (the ratio H2O/CO2 = 17.9).