Source Contamination vs. Crustal Contamination in Subduction Processes

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9814891RuizThis work will evaluate the source and evolution of recent magmas of the Trans Mexican Volcanic Belt. Specifically, there is a fundamental question as to whether the magmas that formed the volcanic rocks have interacted greatly with the continental crust, or whether the mantle derived magmas have not interacted with the crust. This is an old question that has proven difficult to answer with many isotopic systems including those of Sr and Nd. However, there is a potential to strongly constrain the question with a combined Os and O isotopic study. Answers to this question have important implications to models of continental volcanic arc petrogenesis, crustal evolution, regional tectonics and the chemical evolution of the mantle. The Trans Mexican Volcanic Belt is an excellent field laboratory to study the crustal contribution to arc magmatism, because the age and chemistry of the crust changes dramatically from west to east. The crust in western Mexico is Triassic in age and in eastern Mexico, the crust is early Proterozoic in age. This is a significant difference that should be documented in the recent volcanic rocks if the magmas interacted with the crust.