Geochemical constraints on the origin of calcalkaline and alkaline magmas of the eastern Trans-Mexican Volcanic Belt

Abstract

This paper presents major, trace and rare earth element data for calcalkaline and alkaline rocks from the Eastern Trans-Mexican Volcanic Belt (TMVB) and speculates upon their origin and geotectonic significance. Andesites and dacites show geochemical characteristics that preclude their derivation from the basaltic magmas by crystal fractionation. The distribution patterns of the LIL-and HFS-elements are interpreted as indicative of magma formation in a subduction-modified upper mantle. The rhyolites are interpreted as partial melts of the continental crust.