U.S.-Argentina Cooperative Research: Field-Petrologic- Geochemical Study of Recent Volcanic Rocks Erupted Behind the Andean Volcanic Arc

该奖项将支持麻省理工学院的Frederick Frey和阿根廷国家地质服务机构的D. Delpino之间的实地合作。该项目旨在对阿根廷活跃的安第斯火山锋东部从南纬35度到37度喷发的熔岩进行采样，以便了解安第斯山脉南部的火山活动以及智利和阿根廷爆发的相关火山岩。实地工作和采样位于德尔皮诺及其同事已经绘制的地区，但最近的火山特征尚未采样以进行详细的地球化学研究。研究活跃的安第斯火山锋以东500 ~ 200 km处喷发的熔岩主要有两个原因：(1)阿根廷火山锋以东喷发的富含mgo的碱性玄武岩可能比相对演化的形成安第斯火山锋的熔岩更能直接反映其地幔源成分；(2)通过研究锋面上不同距离喷发的熔岩，研究人员可以将地球化学趋势定义为与智利海沟距离的函数。有了这些信息，他们希望对形成安第斯火山弧的这一部分的来源和过程有新的限制。美方在了解火山岩的起源和演化方面具有地球化学分析和解释专业知识。阿根廷人在野外火山学和当地地质学和后勤方面具有专门知识。

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.