Identification of the dominant mechanism of magma genesis for volcanic rocks in the Central Volcanic Zone of the South American Andes is important in understanding the evolution of magmas and in addressing the broader issues of arc magmatism and chemical geodynamics of the crust and mantle. Investigators who have studied andesitic and dacitic stratocones of the Andes have been hampered by an inability to constrain the most primitive magma compositions. The research outlined in this proposal is more likely to yield critical information regarding the nature of parental magmas in the central Andes as it involves a study of lavas from minor volcanic centers that exhibit more primitive characteristics. The project will involve field work, petrographic and mineral chemical analyses, and isotopic and trace element geochemical analyses. A careful microprobe investigation of xenolith- and xenocryst-relationships is also planned.
