Geochemical Evidence for Mantle Origin and Crustal Processes in Volcanic Rocks from Popocatépetl

Elemental, isotopic, and mineral compositions as well as rock textures were examined in samples from Popocatépetl volcano and immediately surrounding monogenetic scoria cones of the Sierra Chichinautzin Volcanic Field, central Mexico. Magma generation is strongly linked to the active subduction regime to the south. Rocks range in composition from basalt to dacite, but Popocatépetl samples are generally more evolved and have mineral compositions and textures consistent with more complicated, multi-stage evolutionary processes. High-Mg calc-alkaline and more alkaline primitive magmas are present in the monogenetic cones. Systematic variations in major and trace element compositions within the monogenetic suite can mostly be explained by polybaric fractional crystallization processes in small and short-lived magmatic systems. In contrast, Popocatépetl stratovolcano has produced homogeneous magma com-positions from a shallow, long-lived magma chamber that is period