RUI: Magmatic Evolution Leading Up to the Modern Aleutian Arc on the Alaska Peninsula

阿拉斯加拥有美国最多的活火山，也是世界上火山最活跃的地区之一。阿拉斯加的大多数火山形成了一个带，包括阿留申群岛，并向陆地延伸到阿拉斯加半岛，最后从安克雷奇穿过库克湾。阿拉斯加半岛有20多座具有历史性活动的火山，其中5座在过去25年中发生过重大喷发，其中包括20世纪世界上最大的一次喷发。该项目将调查阿拉斯加半岛火山系统的生长，并评估影响该地区火山组成和行为的因素。该项目的结果将有助于美国地质调查局和阿拉斯加火山观测站正在进行的工作，以了解该地区的火山行为，该地区每天约有3万人乘坐商用飞机在火山上空运送，火山喷发可能对安克雷奇(阿拉斯加最大的人口中心)和基奈半岛沿线造成严重影响。阿拉斯加半岛也是美国最重要的矿产资源区之一；该项目将提供一个改进的区域框架，这将有助于未来的详细研究，以圈定经济矿藏。通过该项目取得的科学进步也将有助于克拉克湖和卡特迈国家公园的公众宣传任务，这两个国家公园是本研究的几座火山所在的地方。该项目还将为本科生提供高水平的STEM培训。该项目性价比很高，因为它使用了美国地质调查局向公众开放的样本收集，建立在过去对联邦资金的投资基础上。南阿拉斯加是世界上研究会聚边缘长期岩浆作用和地壳生长的最佳地点之一，这一点得到了GeoPRISMS社区的认可，他们选择阿拉斯加/阿留申俯冲带作为俯冲旋回和变形(SCD)倡议的最优先地点。这个为期两年的项目将使GeoPRISMS社区受益，它将进行一项史无前例的天气学研究，评估始新世至阿拉斯加半岛第四纪火成岩的时间和沿走向的地球化学趋势。数据将包括主量元素和微量元素、全岩Ndsr-Hf和锆石Hf同位素，以及火山岩和深成岩的40Ar/39Ar和锆石U/Pb年龄。这项研究的结果将为阿留申弧大陆部分提供新的制约因素，包括：i)沿弧岩浆化学趋势及其与沉积通量和区域构造的关系，ii)俯冲随时间的地球化学产物及其如何影响新大陆地壳的组成，以及iii)俯冲开始的时间及其与太平洋与局部构造过程的关系。这项工作与GeoPRISMS SCD的“重点关注长期边缘演化和物质转移”和“火山弧和大陆的生长和演化”的倡议是一致的，并可与其他项目(即阿拉斯加南部边缘的地球物理研究)结合起来，以在理解会聚边缘岩浆活动的区域控制方面取得进展。

Alaska contains the largest number of active volcanoes in the United States and is one of the most volcanically active regions in the world. Most of the volcanoes in Alaska form a belt that includes the Aleutian Islands and extends landward onto the Alaska Peninsula, ending across the Cook Inlet from Anchorage. The Alaska Peninsula hosts more than 20 volcanoes with historic activity, five with major eruptions in the past 25 years, and includes the world's largest eruption of the 20th century. This project will investigate the growth of the volcanic system on the Alaska Peninsula and evaluate the factors that influence the composition and behavior of volcanoes in this region. The results of this project will contribute to ongoing work of the U.S. Geological Survey and Alaska Volcano Observatory for understanding volcanic behavior in a region where there are roughly 30,000 people per day transported in commercial aircraft over the volcanoes and where eruptions can have severe impact on Anchorage (Alaska's largest population center) and along the Kenai Peninsula. The Alaska Peninsula is also one of the nation's most important mineral resource regions; this project will provide an improved regional framework that will be useful for future detailed studies to delineate economic mineral deposits. Scientific advances made through this project will also contribute to the public-outreach mission of Lake Clark and Katmai National Parks, where several of the volcanoes of this study are located. This project will additionally provide high-level STEM training for undergraduate students. The project is highly cost-effective because it uses publically-available sample collections of the U.S. Geological Survey, building on past investments in federal funding. Southern Alaska is one of the best places in the world to investigate long-term magmatism and crustal growth along a convergent margin, as recognized by the GeoPRISMS community who selected the Alaska/Aleutian subduction zone as the highest priority site for the Subduction Cycles and Deformation (SCD) initiative. This two-year project will benefit the GeoPRISMS community with an unprecedented synoptic study to evaluate temporal and along-strike geochemical trends for Eocene through Quaternary igneous rocks on the Alaska Peninsula. Data will include major and trace element, whole rock Nd-Sr-Hf and zircon Hf-isotopes, and 40Ar/39Ar and zircon U/Pb dating on volcanic and plutonic rocks. The results of this research will provide new constraints on the continental portion of Aleutian arc including: i) along-arc trends in magma chemistry and relationships with sediment flux and regional tectonics, ii) geochemical products of subduction over time and how these influence the composition of new continental crust, and iii) the timing of subduction initiation and relationship to Pacific-wide versus local tectonic processes. This work is in concert with the GeoPRISMS SCD initiatives to "focus on long-term margin evolution and material transfer" and "the growth and evolution of volcanic arcs and continents" and can be integrated with other projects (i.e., geophysical studies of the southern Alaska margin) to yield advances in understanding the regional controls on convergent margin magmatism.