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弗雷德里克·弗雷和阿根廷国家地质服务公司的D·德尔皮诺之间的现场合作。该项目旨在对阿根廷S活动的安第斯火山前锋以东35度至37度的近期喷发的熔岩进行采样，以了解南安第斯山脉的火山活动以及智利和阿根廷喷发的相关火山岩。野外工作和采样位于Delpino和他的同事已经绘制的区域，但最近的火山地貌还没有采样进行详细的地球化学研究。研究这些在活动安第斯火山前缘以东500~200公里处喷发的熔岩有两个主要原因：(1)在前锋以东的阿根廷喷发的富镁碱性玄武岩可能比形成前缘层状火山的相对演化的熔岩更直接地反映其地幔来源成分；(2)通过研究横跨前缘走向的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的距离的函数。有了这些信息，他们预计将对安第斯火山弧这一部分的来源和过程产生新的限制。美方在了解火山岩的起源和演化方面拥有地球化学、分析和解释方面的专业知识。阿根廷人在实地火山学以及当地地质和后勤方面拥有专门知识。

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.