MARGINS: Collaborative Research: A 21st Century Reconnaissance of Aleutian Arc Inception

阿拉斯加/阿留申岛弧是北美地质最活跃的地区，有大量的大地震和50多座活火山的喷发。 准确确定阿留申弧是如何以及何时开始形成的，是理解白令海-阿拉斯加-北太平洋地区起源以及几个环太平洋火山带如何相互关联的关键因素之一。 我们对阿留申岛弧火山活动起源的理解在很大程度上是模糊的，因为阿留申群岛最早期火山岩年龄的数据很少。 阿留申岛弧初期的勘察调查包括采样和确定最古老的火山活动记录的年龄。 目的是确定阿留申岛弧火山活动何时开始，并强调与太平洋其他地方火山活动的开始以及5 200万年前发生的海洋板块相对运动的快速变化之间的潜在联系。 此外，拟议的研究将产生关于阿留申弧如何以及为什么对阿拉斯加和环太平洋地区的人口构成重大火山和地震危险的基本信息。拟议的研究将采用最先进的40 Ar/39 Ar和U-Pb地质年代学，沿着地球化学和同位素分析。 重点是阿马蒂格纳克、乌拉克和基斯卡群岛上的陆上露头，这些岛屿最有潜力探索阿留申群岛的早期历史。 新的地质年代学和地球化学数据将精确地限制阿留申弧开始的时间，喷发产物的成分是什么，以及它们如何在弧的最早历史中演变。 这些信息也将被用来评估现有的阿留申岛弧开始和太平洋板块运动在始新世中期的构造模型。 该项目将在威斯康星大学麦迪逊分校，康奈尔大学和阿拉斯加费尔班克斯大学/美国地质勘探局的科学家之间建立新的合作，这可能有利于GeoPRISMS计划的持续时间。 我们的研究结果将立即用于确定未来通过潜水ROV，疏浚和地球物理成像检查阿留申弧及其弧前结构的工作应该集中在哪里，以最好地解决俯冲带启动的问题。

The Alaska/Aleutian Arc is the most geologically active region in North America with abundant large earthquakes and eruptions from more than 50 active volcanoes. Determining precisely how and when the Aleutian Arc began to form is one of the key elements for understanding the origin of the Bering Sea-Alaska-North Pacific region as well as how several circum-Pacific volcanic zones are related to one another. Our understanding of how volcanism initiated in the Aleutian Arc is clouded due in large part to the scarcity of data that bear on the ages of the earliest volcanic rocks in the Aleutian Islands. The proposed reconnaissance investigation of Aleutian Arc inception involves sampling and determining the ages of the oldest records of volcanism. The aim is to define when Aleutian arc volcanism started and highlight potential linkages with the initiation of volcanism elsewhere in the Pacific and the rapid change in the relative motions of oceanic plates that occurred 52 million years ago. In addition, the proposed research will generate basic information regarding how and why the Aleutian arc poses significant volcanic and earthquake hazards to the population in Alaska and around the Pacific Rim.The proposed research will employ state-of-the-art 40Ar/39Ar and U-Pb geochronology, along with geochemical, and isotopic analysis of the dated rocks. The focus is on subaerial outcrops on Amatignak, Ulak, and Kiska islands, which hold the greatest potential for exploration into the early history of the Aleutians. New geochronologic and geochemical data will precisely constrain when the Aleutian arc inception began, what the compositions of the eruptive products were, and how they evolved through the earliest history of the arc. This information will also be used to evaluate the existing tectonic models of Aleutian arc inception and Pacific Plate motion during the middle Eocene. This project will forge a new collaboration between scientists at UW-Madison, Cornell University, and the University of Alaska-Fairbanks/USGS that may benefit the GeoPRISMS program for its duration. Our findings will be used immediately to determine where future efforts to examine the Aleutian Arc and its fore-arc structures via submersible ROVs, dredging, and geophysical imaging should concentrate to best address questions of subduction zone initiation.