Abstract:Compositions of initial, generally basaltic, rocks of geosynclines are virtually identical regardless of their time and place of formation within the past 3,500 m.y. This constancy of composition through time and place is matched by a similarity of the entire stratigraphie column in each of the studied geosynclines of different age and location. These observations lead to the conclusion that the major element content of the upper mantle has been essentially unchanged during the past 3,500 m.y. except by proces… Show more
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