This award will support field collaboration between Frederick Frey of the Massachusetts Institute of Technology and D. Delpino of the Servicio Geologico Nacional in Argentina. The project aims to sample recent lavas erupted east of the active Andean volcanic front from 35 degrees to 37 degrees S in Argentina, in order to understand volcanism in the southern Andes and the pertinent volcanic rocks erupted in Chile and Argentina. The fieldwork and sampling are located in regions that have been mapped by Delpino and colleagues, but the recent volcanic features have not been sampled for detailed geochemical studies. There are two principal reasons for studying these lavas erupted 500-200 km east of the active Andean volcanic front: (1) it is likely that the MgO-rich alkaline basalts erupted in Argentina east of the front more directly reflect their mantle source composition than the relatively evolved lavas which form the stratovolcanoes on the front; (2) by studying lavas erupted at varying distances across the strike of the front, researchers can define geochemical trends as a function of distance from the Chile trench. With this information, they expect to develop new constraints on the sources and processes involved in creating this portion of the Andean volcanic arc. The U.S. side has geochemical analytical and interpretive expertise in understanding the origin and evolution of volcanic rocks. The Argentines have expertise in field volcanology and in local geology and logistics.
