Volcanic Time Scales, Eruption Rates, and Compositional Diversity at a Continental Arc

该项目由岩石学和地球化学部(EAR)和美洲项目(INT)共同支持，将进行密集的40Ar/39Ar测年研究，并对喷发量进行定量估计，以全面描述墨西哥西部三座大型中部火山及其周围外围喷口的火山历史。这项拟议的研究将扩大沿连续200公里弧段的总火山产出(=1 Ma)的覆盖范围，这对于解决有关不同俯冲参数对弧区喷发产出的作用的全球问题至关重要。此外，关于个别火山田喷发历史的新数据大大增强了地球化学和岩石学数据集，并允许对岩浆分异的机制和时间尺度进行更有力的测试。我们建议的40Ar/39Ar测年计划的结果将有助于在建议的研究区域创建火山灾害地图(由墨西哥科学家独立完成)，该区域是过去1英里内至少6次高度爆炸性喷发的地点，所有喷口都来自纳亚里特州首府特皮克=40公里范围内的喷口。我们与墨西哥国立自治大学(UNAM)的Hugo Delgado-Granados博士合作，促成了密歇根大学和UNAM之间广泛的专业知识和设施交流，以及每隔一年在美国和墨西哥之间轮流进行的一系列学生实地考察。该项目将为两名博士生(一名女性/一名男性)提供培训，他们将熟练掌握Ar年代学、火山岩学、野外测绘和地理信息系统(地理信息系统)软件工具。

This project, jointly supported by the Petrology and Geochemistry (EAR) and the Americas Programs (INT, is to perform an intensive 40Ar/39Ar dating study, coupled with quantitative estimates of erupted volumes, to fully characterize the volcanic history of three large central volcanoes in western Mexico and their surrounding peripheral vents. This proposed study would extend coverage of the total volcanic output (= 1 Ma) along a continuous 200 km arc segment, which is crucial in addressing global questions regarding the role of different subduction parameters on the eruptive output at arcs. In addition, new data on the eruptive history at individual volcanic fields significantly enhances geochemical and petrological data sets and allows more robust tests of the mechanisms and timescales for magma differentiation. The results of our proposed 40Ar/39Ar dating program will assist in the creation of volcanic hazards maps (independently, by Mexican scientists) in the proposed study area, which is the site of at least six, highly-explosive eruptions in the last 1 Myr, all from vents within = 40 km of Tepic, the capital of the state of Nayarit. Our collaboration with Dr. Hugo Delgado-Granados, from the Universidad Nacional Autonoma de Mexico (UNAM), has led to an extensive exchange of expertise and facilities between the University of Michigan and UNAM, as well as a series of student field trips that alternate between the U.S. and Mexico every other year. This project will provide training to two Ph.D. students (one female/one male), who will become skilled in Ar chronology, volcanic petrology, field mapping, and GIS (Geographic Information System) software tools.