The measurements of rockforming and natural radioactive elements as a
result of gamma-spectrometric studies from Phobos-2 space probe orbit
in equatorial zone of Mars are presented. Predominantly basic type of
Martian surface rock composition is corroborated. The data give eviden
ce of the regular character of compositional variations within the stu
died area. The lateral compositional variations presumably are resulti
ng from the variations of bedrock composition as well as of bedrock/so
il ratio.